Systems comprising membrane reinforced colloidal condensed phases, supported liquid membranes, and methods for manufacture thereof

Abstract

A system comprising an electrolyte and a composite membrane is described. The composite membrane comprises a microporous polymer scaffold comprising a plurality of scaffold pores, each of said scaffold pores having a pore volume and the microporous polymer scaffold having a scaffold pore volume, and a colloidal condensed phase within the plurality of scaffold pores. The colloidal condensed phase comprises sub-micron particles within the scaffold pore volume, and the composite membrane comprises a plurality of composite membrane pores which are defined at least in part by the colloidal condensed phase. The system may be useful as an electrochemical separator. Also described are an electrochemical device comprising an anode, a cathode, and the system of the disclosure, uses of the system, and methods of manufacturing the system. A supported liquid membrane comprising a composite membrane as described in the disclosure, and a liquid is also described.

Description

P390218USP 3252US01SYSTEMS COMPRISING MEMBRANE REINFORCED COLLOIDAL CONDENSED PHASES, SUPPORTED LIQUID MEMBRANES, AND METHODS FOR MANUFACTURE THEREOFFIELD OF THE DISCLOSUREThis disclosure relates to systems comprising membrane reinforced colloidal condensed phases, and methods for manufacture thereof. The systems of the present disclosure are particularly suitable for use as electrochemical separators.This disclosure also relates to supported liquid membranesBACKGROUND

[0001] Opaloids are solid materials comprising particles in tightly packed arrangements where said arrangements have a degree of order that may range from crystalline to nearly amorphous. Opaloids can have many interesting properties, such as a narrow distribution of pore sizes, relatively high porosity, crush resistance, stability at high temperatures, stability in many chemical environments, and wettability with various fluids (including water). However, the production of high-quality opaloids for practical applications can be very challenging, particularly for opaloids comprising ceramics because of the brittle nature of such materials. For example, significant challenges exist in: 1) fabricating large areas (e.g., areas larger in extent than about one millimeter to several centimeters in at least one dimension) with high integrity (for example, relatively free of through-plane defects such as cracks); 2) making highly flexible, free-standing structures that enable efficient roll-to-roll processing; 3) making mechanically robust structures that can withstand handling, installation, and use in industrial applications; and 4) enabling sufficiently rapid fabrication for economical, high-volume production.

[0002] An electrochemical device comprises an electrochemical cell, and an electrochemical cell may comprise an electrochemical separator. An electrochemical separator is a material, for example a membrane or diaphragm, that prevents electrical contact between the anode and cathode within an electrochemical cell, thus reducing the risk of a short circuit, while allowing ion conduction between the anode and cathode by means of an electrolyte. Electrochemical separators may perform other vital functions as well, for example they may prevent reactive species (e.g., gases or ions) from the anode and cathode sides of the cell from freely mixing. To improve the overall performance or economics of an electrochemical device, it may be desirable to improve the efficacy of the separator (e.g., toP390218USP 3252US01further reduce the risk of a short circuit, or to further reduce the crossover of reactive species through the separator). It may also be desirable to improve the range of conditions over which the separator is effective (e.g., by enabling the cell to operate at higher temperatures, increasing the compressive pressure an electrochemical cell can withstand, or preventing catastrophic failure during a safety event such puncture of the electrochemical cell). However, it is also generally desirable to minimize the ionic resistance, mass, and / or volume of electrochemical separators within electrochemical cells (e.g., by making them thinner). These goals are often in tension, for example making a separator thinner may compromise its ability to prevent electrical contact between the anode and cathode or reduce its ability to separate reactive species.

[0003] Alkali metal and alkali metal-ion rechargeable batteries may comprise a negative electrode and a positive electrode. During discharge, the active material of the negative electrode is oxidized while the active material of the positive electrode is reduced. During charge the situation is reversed: the active material of the negative electrode is reduced while the active material of the positive electrode is oxidized. By convention, the negative electrode is typically called the “anode” and the positive electrode is typically called the “cathode.” The terms “anode” and “cathode” will be used herein according to this convention.

[0004] A supported liquid membrane (SLM) is a membrane system where a liquid is immobilized within the pores of a membrane support (e.g., a microporous polymer scaffold), typically via capillary forces. Supported liquid membranes have been extensively studied as having excellent properties for various types of separations. However, challenges exist in their application because current SLMs can suffer from expulsion of the supported liquid due to trans-membrane pressure gradients; squeeze-out of the supported liquid due to mechanical compression; and the membrane supports can lack chemical, thermal, and / or mechanical stability.

[0005] Accordingly, a need exists to develop products and methods that allow for the production of large, high-integrity opaloids and permit some or all of the advantageous properties of opaloids to be utilized more readily and economically in practical applications. Additionally, there is a need for improved membrane supports for supported liquid membranes that address some or all of the aforementioned issues with current supported liquid membranes. Similarly, there is a coinciding need for improved materials for use as electrochemical separators.P390218USP 3252US01Summary of the InventionColloidal Condensed Phases

[0006] The term “colloidal condensed phase” herein refers to a phase or range of phases comprising the particulate material, in which the positions of the particles thereof are constrained by adjacent particles. The particles forming a colloidal condensed phase are comparatively close-packed in comparison to the colloid from which it is made. The degree of order present in a colloidal condensed phase can range from a substantially amorphous material to a relatively ordered “colloidal crystal” phase with close packing of particles having repeating order over multiple (e.g. more than around 5, more than around 10, more than around 100, more than around 500, or more than around 1000 unit cells in two or three unit cell axes). The term “colloidal condensed phase” includes the “opaloid” materials disclosed herein.

[0007] The degree of order may vary within a region of the colloidal condensed phase, or between regions of colloidal condensed phase within different pores of the microporous polymer scaffold. The colloidal condensed phase may include regions or domains with different degrees of order.

[0008] As known in the art, colloids may undergo a colloidal glass transition as a function of increased particle packing density. The nature of the phase change behaviour with particle concentration and the degree of order present in the resulting colloidal condensed phase depends inter alia on the particulate size, morphology and dispersity.

[0009] As known to one skilled in the art, a colloidal crystal comprises crystal domains of particulate solid in a repeating three-dimensional array, typically with cubic or hexagonal symmetry. The particles thereof may be arranged in a close packed array (such as cubic close packed or hexagonal close packed). An array will comprise a repeating unit cell, having two or three unit cell axes. The axes may, but need not be, orthogonal. It will be understood that the size of crystal domains will be governed at least in part by the size and shape of the pores within which they are formed. The colloidal crystal regions of the colloidal condensed phases may form domains of at least 5 or 10, or 100 or more unit cells in one, two or three unit cell axes.

[0010] Accordingly, the term, “continuous ceramic phase” can also be referred to as “colloidal condensed phase” and this refers to a phase or range of phases comprising the particulate material (e.g. ceramic particles), in which the positions of the particles thereof are constrained by adjacent particles.The term, “ceramic particles” is to be understood to refer to inorganic particulate materials. As used herein, “ceramic particles” are intended to encompass a subset of inorganicP390218USP 3252US01submicron particles comprising inorganic non-metallic, non-carbonaceous materials comprising metal, non-metal, or metalloid atoms held by ionic or covalent bonds, and wherein the ceramic particle structure is electrically neutral.According to a first aspect of the disclosure, there is provided a system comprising:an electrolyte; anda composite membrane; wherein the composite membrane comprises:a microporous polymer scaffold having a scaffold matrix and a plurality of scaffold pores having a scaffold pore volume, anda colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles,wherein the three-dimensional packing arrangement of sub-micron particles exhibits at least one structure factor peak in Lorentz-corrected SAXS data.A structure factor peak herein may be defined as in scipy signal find_peaks: " finds all local maxima by simple comparison of neighboring values." E.g. a peak data point will have 2 neighboring values of lesser value. Structure factor peaks generally have a prominence of at least 20%, where prominence is the maximum value of the structure factor peak normalized by the minimum Lorentz corrected intensity in the adjacent region corresponding to interparticle distances larger than the detected peak. Structure factor peaks may also have a prominence of at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 75%, at least about 100%, at least about 200%, at least about 300%, at least about 400%, at least about 500%, or at least about600%. -Structure peaks may also be characterized by their full width at half-prominence. Full width at half prominence may be calculated as the width of the peak (i.e., the length of the line that intersects the contours of the peak at a given Lorentz-corrected intensity) at half the prominence. Structure factor peaks may have a full width at half prominence of less than about 100%, or less than about 70%, or less than about 50%, of the structure peak Interparticle Distance (ID). Inter- particle distances (ID) larger than 100nm, but smaller than 300nm may be evaluated by use of Ultra Small-Angle X-ray Scattering (USAXS).The submicron particles may comprise submicron ceramic particles.P390218USP 3252US01In some embodiments, the submicron particles comprise core-shell particles comprising the submicron particles coated with a shell. The shell may comprise alumina AI2O3, boehmite (AIO(OH)) or combinations thereof.The submicron particles may have a particle diameter or effective diameter of from about 5 nanometers to about 200 nanometers.The microporous polymer scaffold may comprise a microporous hydrocarbon scaffold and preferably, comprises a microporous polyolefin scaffold.The microporous hydrocarbon polymer scaffold may comprise any one or more polymers selected from polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), or combinations thereof.The largest pore of the plurality of scaffold pores, may have a pore diameter, as determined by bubble point, which is from about 3 to about 15 times the particle diameter or effective particle diameter of the submicron ceramic particles.The plurality of scaffold pores may have a scaffold pore diameter which from about 1 to about 15 times of a particle diameter or effective particle diameter of the submicron ceramic particles.The inter-particle pores between the sub-micron ceramic particles are preferably, defined by an inter-particle distance within the three-dimensional packing arrangement of sub-micron ceramic particles, and wherein the inter- particle distance is from about 0.5 times to about 3 times the particle diameter or effective particle diameter of the submicron ceramic particles.The continuous ceramic phase disposed within the scaffold pore volume may have a ratio (d / D) of an inter-particle pore size, d, to particle diameter or effective diameter, D, of from about 0.2 to about 1.2.The packing density of the ceramic particles may be from about 0.40 to about 0.85.The porosity of composite membrane may be from about 30% to about 70%.The volume ratio of sub-micron ceramic particles to scaffold matrix in the composite membrane is optionally, from about 0.5 to about 3.P390218USP 3252US01The colloidal condensed phase may extend substantially through the entire thickness of the scaffold.The contact thickness of the composite membrane may be from about 1 micron to about 150 microns.In some embodiments, the electrolyte is arranged, in use, to permit the transport of ions across the composite membrane.The composite membrane may comprise a total membrane thickness and the electrolyte is within the total membrane thickness.In some embodiments, the electrolyte is incorporated at least partially within the composite membrane pores.The microporous polymer scaffold may comprise a polymer electrolyte.The electrolyte may be incorporated within the colloidal condensed phase.The polymer electrolyte membrane layer may be arranged adjacent to the microporous polymer scaffold.The electrolyte may comprise a liquid electrolyte.The electrolyte may comprises at least one of a liquid alkaline electrolyte or a liquid acidic electrolyte.The microporous polymer scaffold may have a bubble point pressure equal to or greater than 1 bar.The microporous polymer scaffold may have a bubble point pressure equal to or greater than 1.9 bar.The composite membrane may comprise a bubble point of equal to or greater than 10 bar. The colloidal condensed phase may comprises a three- dimensional packing arrangement of sub-micron particles, and wherein the composite membrane pores are defined at least in part by an inter- particle distance within the packing arrangement.The inter-particle distance may be from about 0.5 times to about 3 times the sub-micron diameter or effective diameter.The sub-micron particles may have a sub-micron particle diameter or effective diameter, and the composite membrane pores have a composite membrane pore size, and wherein theP390218USP 3252US01mode composite membrane pore size is within 0.15 to 2 times the sub-micron particle diameter or effective diameter.The porosity of the composite membrane may be between about 10 to 75%.In some embodiments, the colloidal condensed phase comprises an inter-particle pore size of about 0.15 to about 1.5 times the sub-micron particle diameter or equivalent diameter.The sub-micron particles may have a diameter or an equivalent diameter of from 1 nm to 100 nm.The sub-micron particles preferably, comprise at least one of ceramics or glasses. The ceramic may be selected from: silicon dioxide, aluminium oxide, titanium dioxide, cerium oxide, zirconium dioxide, yttria-stabilized zirconium dioxide, other oxides, and other classes of ceramics including carbides, nitrides, sulfides, borides, phosphides, selenides, titanates, carbonates, nitrates, sulfates, borates, and phosphates, or combinations thereof.The sub-micron particles may comprise at least two different populations of sub-micron particles, wherein a first population of sub-micron particles has a first particle diameter (or effective particle diameter) and a second population of sub-micron particles has a second particle diameter (or effective diameter).In some embodiments, the composite membrane comprises a plurality of microporous polymer scaffolds.In some embodiments, the plurality of scaffold pores are preferably, at least partially filled with the colloidal condensed phase. The colloidal condensed phase may extend continuously across at least a portion of the scaffold pores in at least one direction by at least about 1 mm.The microporous polymer scaffold may have a first direction, a second direction and a thickness direction, wherein the first direction is orthogonal to the second direction, and the first and second directions are each orthogonal to the thickness direction, and wherein the microporous polymer scaffold has a matrix tensile strength (MTS) in the second direction of at least about 55 MPa, wherein the second direction is the direction in which the microporous polymer scaffold has its minimum matrix tensile strength.The microporous polymer scaffold may have a geometric mean MTS of at least about 90 MPa.The microporous polymer scaffold may have a mass-per-area ranging from about 1 g / m2to about 30 g / m2.P390218USP 3252US01The microporous polymer scaffold may be selected from one of a non-fluorinated polymer, a partially fluorinated polymer, a perfluorinated polymer, and any combination thereof.The microporous polymer scaffold may comprise polyolefins, optionally, polyethylene (PE) or polypropylene (PP).In some embodiments, the microporous polymer scaffold comprises at least two microporous polymer scaffolds, optionally, wherein a first microporous polymer scaffold comprises a first polymer and the second microporous polymer scaffold comprises a second polymer; optionally, wherein the first microporous polymer scaffold comprises polyethylene (PE) and the second microporous polymer scaffold comprises polypropylene (PP).The microporous polymer may comprise any polymer selected from the following group: a polytetrafluoroethylene (PTFE), a polyethylene (PE), or a copolymer of PTFE and PE, expanded polyethylene (ePE), expanded polytetrafluoroethylene (ePTFE), or combinations thereof.The composite membrane may comprises a plurality of composite layers, and wherein at least one of the composite membrane layers comprises an integrated ion transport layer, optionally, comprising a polymer electrolyte membrane layer.Thus, the composite membrane may further comprise an integrated ion transport layer. The integrated ion transport layer may comprise any one or more of the following:- Anion exchange polymers;- Ion-solvating polymers;- Polymers of intrinsic microporosity;- Ceramic particle layer; and- Nano-cellulose or other water-getters or sorbing agents.In a further aspect of the disclosure, there is provided an electrochemical device comprising: an anode; a cathode; and the system of the disclose as referred to hereinabove. In such electrochemical device, the electrolyte is positioned between the anode and the cathode to permit, in use, the transport of ions between the cathode and the anode.In some embodiments, the anode comprises any one selected from nickel, cobalt, and iron. In some embodiments, the cathode comprises any one selected from nickel, platinum, and carbon.P390218USP 3252US01The electrochemical device may be one of: an electrolyzer, a redox flow battery, a fuel cell, or a rechargeable battery.The electrochemical device may be used for the electrolysis of water to produce hydrogen or as an electrolyzer or a redox flow battery.In another aspect of the present disclosure, there is provided a method of manufacturing the system or the electrochemical device wherein the method comprises:a) obtaining a composite membrane wherein the composite membrane comprises a microporous polymer scaffold, wherein the microporous polymer scaffold has a polymer scaffold matrix and a plurality of scaffold pores, the microporous polymer scaffold having a scaffold pore volume and having a porosity from about 70% to about 96%;(b) incorporating sub-micron particles into the scaffold pore volume of the microporous polymer scaffold; and(c) consolidating the sub-micron particles such that they form a colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles; andwherein the three-dimensional packing arrangement of sub-micron particles exhibits at least one structure factor peak in Lorentz-corrected SAXS data.The microporous polymer scaffold may have a porosity of at least about 75%.In another aspect of the disclosure, there is also provided a supported liquid membrane comprising:a composite membrane wherein the composite membrane comprises:a microporous polymer scaffold having a scaffold matrix and a plurality of scaffold pores having a scaffold pore volume, anda colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles,P390218USP 3252US01wherein the three-dimensional packing arrangement of sub-micron particles exhibit at least one structure factor peak in Lorentz-corrected SAXS data.

[0011] The composite membranes disclosed herein may have many advantageous properties, for instance, for use in electrochemical separators. Through a unique balance of properties, the composite membranes may enable improvements over state-of-the-art separators in multiple ways (“improvement vectors”). For example, they may simultaneously enable some or all of the following improvements:1) Make the separator thinner and thereby reduce ionic resistance and improve the volumetric and gravimetric energy density of the electrochemical device.2) Increase the compressive pressure the separator can withstand without short circuiting, e.g., to improve the safety of the electrochemical device, or to enable higher compressive loads and thereby improve the performance of the electrochemical device by reducing contact resistances within the electrochemical cell3) Reduce unwanted crossover of reactive species or other materials through the separator and thereby improve the safety of the electrochemical device and enhance the operational flexibility of the electrochemical device.4) Improve the handleability of the separator, e.g., to enable efficient processing, shipping, handling, storage, and installation of the separator in the final application (i.e., in the electrochemical cell in the electrochemical device), simplifying logistics and thereby facilitating scale-up and cost-reduction of the electrochemical device.5) Enhance the operable temperature range of the separator and thereby improve the performance of the electrochemical device by enabling higher-temperature operation (resulting in e.g., faster electrode kinetics and / or higher electrolyte conductivity within the electrochemical cell).6) Improve the dimensional stability of the separator at high temperature and thereby improve the safety of the electrochemical device by preventing catastrophic failure during e.g., a puncture of the electrochemical cell.

[0012] These improvement vectors are often in tension, in particular item #1 may conflict with items #2 - #4. These tensions result in so-called “engineering trade-offs” between separator attributes, which may be embodied in ratios for a given separator, such as the ratio of ionic conductance to degree of protection against short circuits, or the ratio of ionic conductance to gas or liquid permeance, which the separators disclosed herein may improve.

[0013] The composite membranes may be readily wettable with aqueous liquid electrolyte to enable high ionic conductance. Furthermore, the composite membranes may be stable under extremely chemically aggressive conditions. Accordingly, when combined with aP390218USP 3252US01suitable electrolyte arrangement, the inventors have shown that the systems of the present disclosure are particularly effective for use as electrochemical separators.

[0014] The composite membranes of the present disclsoure may also be referred to as membrane-reinforced opaloids (MROs) or reinforced opaloid membranes. The composite membranes of the present disclosure may also be referred to as membrane-reinforced colloidal crystals or reinforced colloidal crystal membranes. The composite membranes of the present disclosure may also be referred to as membrane-reinforced colloidal semicrystals or reinforced colloidal semicrystal membranes. The composite membranes of the present disclosure may also be referred to as reinforced colloidal glass membranes or membrane-reinforced colloidal glasses

[0015] The inventors have surprisingly discovered that the quality of the composite membrane may be dramatically improved when the composite membrane comprises a microporous polymer scaffold as set out in the appended claims, wherein the composite membrane comprises:a microporous polymer scaffold having a scaffold matrix and a plurality of scaffold pores having a scaffold pore volume, anda colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles,wherein the three-dimensional packing arrangement of sub-micron particles exhibits at least one structure factor peak in Lorentz-corrected SAXS data.

[0016] In some embodiments, the composite membrane may be characterized by tight pores, for example a microporous polymer scaffold having a bubble point pressure of equal to or greater than about 1.9 bar, or equal to or greater than about 2 bar.

[0017] In some embodiments, it has been shown that composite membranes of the present disclosure comprising a microporous polymer scaffold which has a bubble point pressure of equal to or greater than about 1.9 bar, in combination with the colloidal condensed phase comprising sub-micron particles within the scaffold pore volume, provides for a composite membrane which may have a bubble point pressure beyond what would be expected, for example, equal to or greater than about 10 bar.

[0018] The inventors have realized the provision of composite membranes with highly tunable pore size, and properties which can embody the advantageous properties of colloidal condensed phase materials (which are a form of colloidal glass) whilst providing improvedP390218USP 3252US01stability, integrity, and reproducibility. The composite membranes of the present disclosure may be effective in a wide range of applications. For example, the composite membranes may be effective as separators in electrochemical applications (i.e., as electrochemical separators).

[0019] The composite membrane may comprise a plurality of microporous polymer scaffolds. The number of microporous polymer scaffolds is not particularly limited, and the composite membrane may comprise one microporous polymer scaffold, or two microporous polymer scaffolds, or three microporous polymer scaffolds, or four microporous polymer scaffolds, or between 1 and 20 microporous polymer scaffolds, or between 1 and 10 microporous polymer scaffolds. At least one of the plurality of microporous polymer scaffolds may have a bubble point pressure of equal to or greater than about 1.9 bar, or equal or greater than about two bar, and the sub-micron particles incorporated within the scaffold pore volume.

[0020] The composite membrane may comprise other layers and components besides the microporous polymer scaffold and the sub-micron particles, such that the composite membrane is suitable for its intended function.

[0021] The composite membrane may comprise an adjacent functional layer (e.g., a buttercoat or laminated layer) such as:

[0022] - Anion exchange polymers

[0023] - Ion-solvating polymers

[0024] - Polymers of intrinsic microporosity

[0025] - Ceramic particle layer

[0026] - Nano-cellulose or other water-getters or sorbing agents.

[0027] In another aspect of the disclosure, the composite membrane may comprise particle blends including, but not limited to the following:

[0028] - blends of different size particles

[0029] - blends of multiple ceramics; and

[0030] - blends of at least one ceramic particle with at least one polymer particle.

[0031] In the system of the present disclosure, the electrolyte may be arranged, in use, to permit the transport (e.g., the selective transport) of ions (e.g., via the vehicular or Grotthuss mechanisms) across the composite membrane. The electrolyte may comprise a single electrolyte or multiple electrolytes. In embodiments where there is more than one electrolyte, the electrolytes may be located in the same part or area, or in different parts of the composite membrane. In the system of the present disclosure, the composite membrane may compriseP390218USP 3252US01a total membrane thickness, and the electrolyte is within the total membrane thickness. As used herein, the total membrane thickness may encompass the overall thickness of any component parts of the composite membrane. For example, in some cases, the composite membrane may comprise a plurality of layers, at least one of which comprises the microporous polymer scaffold comprising the colloidal condensed phase. The total membrane thickness may incorporate other layers arranged adjacent to the composite membrane. The other layers may comprise for example, polymer electrolyte layers, or any other component parts required by the particular electrochemical application.

[0032] The electrolyte may be incorporated at least partially within the composite membrane pores. The composite membrane pores may be at least partially filled with the electrolyte. As used herein, at least partially filled is taken to encompass composite membranes where a percentage of the composite membrane pores are filled with electrolyte, for example up to about 100%, or about 99%, or about 95% or about 75% or about 50%, or about 25%, or any percentage in between. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 100%, for from about 20% to about 100%, from about 30 % to about 100%, from about 40 % to about 100 %, from about 50 % to about 100%, from about 60% to about 100%, from about 70 % to about 100 %, from about 80% to about 100 %, from about 90 % to about 100 %. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 95%, for from about 20% to about 95%, from about 30 % to about 95%, from about 40 % to about 95 %, from about 50 % to about 95 %, from about 60% to about 95%, from about 70 % to about 95 %, from about 80% to about 95 %, from about 90 % to about 95%. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 90%, for from about 20% to about 90%, from about 30 % to about 90%, from about 40 % to about 90 %, from about 50 % to about 90%, from about 60% to about 90%, from about 70 % to about 90 %, from about 80% to about 90 %. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 80%, for from about 20% to about 80%, from about 30 % to about 80%, from about 40 % to about 80 %, from about 50 % to about 80%, from about 60% to about 80%, from about 70 % to about 80%. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 75%, for from about 20% to about 75%, from about 30 % to about 75%, from about 40% to about 75 %, from about 50 % to about 75%, from about 60% to about 75%, from about 70 % to about 75%. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 75%, for from about 20% to about 70%, from about 30 % to about 70%, from about 40% to about 70 %, from about 50 % to about 70%, from about 60% to about 70%. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 50%, forP390218USP 3252US01from about 20% to about 50%, from about 30 % to about 50%, from about 40% to about 50 %. The percentage of the composite membrane pores filled with electrolyte may be from about 10% to about 25%, for from about 20% to about 25%. At least partially filled can also be taken to encompass composite membranes where the plurality of composite membrane pores have the electrolyte within their pore volume, but the pore volume of an individual composite membrane pore is not completely filled with electrolyte.

[0033] The composite membrane pores may be substantially filled with the electrolyte. As used herein, the term “filled” may be taken to mean that substantially all of the pore volume of the composite membrane pores is occupied by the electrolyte.

[0034] The microporous polymer scaffold may comprise the electrolyte In other words, the microporous polymer scaffold may comprise a polymer electrolyte. The microporous polymer scaffold may be formed from the polymer electrolyte.

[0035] The electrolyte may be incorporated within the colloidal condensed phase (“opaloid”). As described herein, the opaloid comprises a three-dimensional packing arrangement of sub-micron particles. The electrolyte may be incorporated within the three-dimensional packing arrangement. The three-dimensional packing arrangement encompasses the three-dimensional packing arrangements as outlined in the description of MROs morphology sections provided herein For example, the electrolyte may be incorporated within the inter- particle space of the three-dimensional packing arrangement of sub-micron particles. The electrolyte may be incorporated within any interfacial particlescaffold pores. The opaloid may comprise sub-micron particles that comprise the electrolyte.

[0036] In some examples, the composite membrane comprises a plurality of composite layers. At least one of the composite membrane layers may comprise a polymer electrolyte layer (or polymer electrolyte membrane layer). The polymer electrolyte membrane layer may be arranged adjacent to the microporous polymer scaffold having the opaloid incorporated therein. The polymer electrolyte membrane layer may be laminated or otherwise joined to the to the microporous polymer scaffold having the opaloid incorporated therein.

[0037] The electrolyte may comprise any suitable material for the intended application. The electrolyte is not particularly limited and any material known in the art may be used as the electrolyte. For example, the electrolyte may be substantially organic or substantially aqueous. The electrolyte may comprise a liquid electrolyte. The liquid electrolyte may comprise a liquid alkaline electrolyte. The liquid alkaline electrolyte may be an aqueous or substantially aqueous alkaline solution. The liquid alkaline electrolyte may comprise a metal hydroxide. The metal hydroxide may comprise sodium hydroxide or potassium hydroxide.P390218USP 3252US01The electrolyte may comprise a liquid acidic electrolyte. The liquid acidic electrolyte may comprise a strong acid such as sulfuric acid. The electrolyte may comprise an aqueous electrolyte with very low pH (e.g., a pH of about 1s such as a concentrated strong acid), or a very high pH (e.g., a pH of about 14, such as a concentrated strong base), or any intermediate value of pH. The electrolyte may have a very high pH (e.g., above about pH 10, or above about pH 11, or above about pH 12, or above about pH 13, or above about pH 14). The electrolyte may have a very low pH (e.g., below about pH 5, or below about pH 4, or below about pH 3, or below about pH 2, or below about pH 1).

[0038] The composite membrane may have a low gas permeance. The low gas permeance may be represented by a Gurley number > 500 s, or a Gurley number > 1000 s, or a Gurley number > 2000 s, or a Gurley number > 5000 s.

[0039] The composite membrane may have a low liquid permeance. The liquid permeance may be < 100 L / m2 / h / bar or < 50 L / m2 / h / bar or < 10 L / m2 / h / bar at a differential pressure in the range of from 1 to 50 bar and with isopropyl alcohol (I PA) as the challenge fluid. In some embodiments it may be preferable to substitute a different challenge fluid, for example if required for material compatibility, so long as the rheological properties are similar to I PA and the values of liquid permeance are adjusted for the viscosity of the new challenge fluid under the assumption that the liquid permeance is inversely proportional to the viscosity of the challenge fluid (i.e., for a challenge fluid with double the viscosity of IPA the permeance should be half of what would be measured with IPA).

[0040] The composite membrane may be stable in a liquid alkaline electrolyte. This means that the components, e.g., the microporous polymer scaffold and opaloid, and properties of the composite membrane do not degrade to a significant extent in the liquid alkaline electrolyte such that the system for use as an electrochemical separator can function as intended. This may be evident from the stability of one or more of the properties of the composite membrane in the liquid alkaline electrolyte, such as MTS, bubble point or MPA over time, such as over a period of 24 hours, 1 week, 1 month, up to 3 months, up to 6 months, and up to 1 year.

[0041] The composite membrane may be stable in a liquid acidic electrolyte. This means that the components, e.g., the microporous polymer scaffold and opaloid, and properties of the composite membrane do not degrade to a significant extent in the liquid acidic electrolyte such that the system for use as an electrochemical separator can function as intended. This may be evident from the stability of one or more of the properties of the composite membrane in the liquid acidic electrolyte, such as MTS, bubble point or MPA over time, such as over a period of 24 hours, 1 week, 1 month, up to 3 months, up to 6 months, and up to 1 year.P390218USP 3252US01

[0042] The composite membrane may have an ex-situ ionic resistance as defined herein of about 0.1 ohm to about 1 ohm, or from about 0.1 ohm to about 0.5 ohm, or from about 0.1 ohm to about 0.3 ohm, or from about 0.2 ohm to about 0.4 ohm, or from about 0.3 ohm to about 0.7 ohm, or from about 0.3 ohm to about 0.6 ohm, or from about 0.2 ohm to about 0.4 ohm, or from about 0.3 ohm to about 0.5 ohm, or from about 0.4 ohm to about 0.8 ohm, or from about 0.5 ohm to about 1 ohm, or from about 0.5 ohm to about 0.7 ohm, or from about 0.7 ohm to about 1 ohm, or from about 0.6 ohm to about 0.8 ohm. The composite membrane may have an ionic resistance of about 0.3 ohm to about 0.7 ohm.

[0043] According to a second aspect, there is provided an electrochemical device comprising an anode, a cathode and the system of the first aspect.

[0044] The electrolyte may be positioned between the anode and the cathode to permit, in use, the transport (e.g., the selective transport) of ions (e.g., via the vehicular or Grotthuss mechanisms) between the cathode and the anode.

[0045] The anode and cathode (together, the “electrodes”) may comprise any one of the following: nickel, cobalt, iron, platinum, and carbon.

[0046] According to a third aspect, there is provided the use of the system as defined in the first aspect or the electrochemical device as defined in the second aspect in the electrolysis of water to produce hydrogen.

[0047] According to a fourth aspect, there is provided the use of the system as defined in the first aspect or the electrochemical device as defined in the second aspect in one of: an electrolyzer, a redox flow battery.

[0048] According to a fifth aspect of the present disclosure, there is provided a method of manufacturing the system as defined in the first aspect or the electrochemical device as defined in the second aspect. The method comprises: (a) obtaining a composite membrane, wherein the composite membrane comprises a microporous polymer scaffold comprising a plurality of scaffold pores, each of said scaffold pores having a scaffold pore volume; and an opaloid within the plurality of scaffold pores, wherein the opaloid comprises sub-micron particles within the scaffold pore volume; and wherein the composite membrane comprises a plurality of composite membrane pores which are defined at least in part by the opaloid; (b) arranging an electrolyte relative to the composite membrane to allow for the system to be used as an electrochemical separator.

[0049] The method step (a) may comprise step (i) obtaining a microporous polymer scaffold, wherein the microporous polymer scaffold comprises a plurality of scaffold pores,P390218USP 3252US01each of said scaffold pores having a pore volume and the microporous polymer scaffold having a scaffold pore volume; step (ii) incorporating sub-micron particles into the scaffold pore volume of the microporous polymer scaffold within the scaffold pores, and step (iii) forming a opaloid within the scaffold pore volume. In one embodiment the microporous polymer scaffold might have a bubble point pressure of equal to or greater than 2 bar. In some embodiments the microporous polymer scaffold might have a bubble point pressure of equal to or greater than 1.9 bar.

[0050] The method may comprise imbibing the microporous polymer scaffold with a colloidal system comprising the sub-micron particles.

[0051] The method step (b) may further comprise at least one of: incorporating the electrolyte at least partially into the composite membrane pores; forming the microporous polymer scaffold from a polymer electrolyte; incorporating the electrolyte into the opaloid; arranging a polymer electrolyte membrane layer adjacent to the microporous polymer scaffold.

[0052] Incorporating the electrolyte at least partially into the composite membrane pores may comprise imbibing the composite membrane with the electrolyte. Incorporating the electrolyte at least partially into the composite membrane pores may comprise wetting the composite membrane with the electrolyte.

[0053] According to a sixth aspect, there is provided a supported liquid membrane comprising a composite membrane comprising a microporous polymer scaffold comprising a plurality of scaffold pores, each of said scaffold pores having a scaffold pore volume; and an opaloid within the plurality of scaffold pores, wherein the opaloid comprises sub-micron particles within the scaffold pore volume; and wherein the composite membrane comprises a plurality of composite membrane pores which are defined at least in part by the opaloid; and a liquid, wherein the composite membrane pores are at least partially filled with the liquid and the liquid is retained within the composite membrane pores.

[0054] The composite membrane may be the composite membrane described with respect to the first aspect. In some embodiments, the composite membranes having submicron particles with a particle diameter of between about 1 to 100 nm, or about 2 to 80 nm, or about 3 to 60 nm, or about 4 to 40 nm, or about 5 to 35 nm, or about 5 to 30 nm, or about 5 to 25 nm may be a membrane support for a supported liquid membrane. The membrane support for the SLM may comprise sub-micron particles that comprise a ceramic and / or a glass.

[0055] The composite membrane further comprises a liquid within the composite membrane pores. The liquid preferably may have adequate durability (e.g., regarding thermal, chemical, electrochemical, radiation, and / or other stresses). The liquid may comprise high-P390218USP 3252US01performance fluids such as ionic liquids, deep eutectic solvents, or low-vapor-pressure oils. Ionic liquids can, for example, be liquid at less than 100°C (i.e., so-called “room-temperature ionic liquids” or RTILs), have tuneable properties such as viscosity and solubility, and can be stable at high voltage and / or high temperatures.

[0056] The composite membrane pores may be substantially filled or partially filled with the liquid. The liquid is retained within the composite membrane pores. For example, the liquid may be retained within the composite membrane pores via capillary forces. The liquid may be retained in the composite membrane pores when subjected to significant trans-membrane pressure, for example a trans-membrane pressure of at least between about 1 bar to about 28 bar, or between about 5 bar to about 25 bar, or between about 10 bar to about 20 bar, or about 2 bar to about 15 bar, or about 7 bar to about 28 bar. The liquid may be retained in the composite membrane pores when subjected to mechanical compression.

[0057] The sub-micron particles may be the same as the sub-micron particles described above in the first aspect and in the detailed description below.

[0058] The supported liquid membrane may be particularly useful for use in separations and / or electrochemical applications (e.g., as an electrochemical separator).

[0059] According to a seventh aspect of the present disclosure, there is provided a method of manufacturing a supported liquid membrane.

[0060] The method may comprise obtaining a composite membrane as described in any of the method steps a) including sub-steps (i), (ii) and (iii), and any related steps of the fifth aspect, and further comprising incorporating a liquid within at least a portion of the composite membrane pores. The liquid is retained within the composite membrane pores.

[0061] The method may comprise at least partially filling the composite membrane pores with a liquid to be supported. The method may comprise substantially filling the composite membrane pores with a liquid to be supported. The filling may comprise wetting the composite membrane with the liquid to form a supported liquid membrane.

[0062] The composite membrane pores may be filled with the liquid by spontaneous wetting, or the wetting may be assisted by any of a variety of means that will be evident to one of ordinary skill in the art, such as by applying a differential pressure to force the liquid into the composite membrane, raising the temperature of the liquid to lower its viscosity, pre-wetting the composite membrane with another miscible fluid, and any other appropriate methods as would be apparent to the person ordinarily skilled in the art.

[0063] Examples of high-performance liquids to be supported in the supported liquid membrane may include ionic liquids (ILs) including room -temperature ionic liquids (RTILs),P390218USP 3252US01deep eutectic solvents, and low-vapor-pressure oils. The method may comprise layering a plurality of microporous polymer scaffolds. At least one of the plurality of microporous polymer scaffolds may have a bubble point pressure of equal to or greater than 2 bar, wherein the microporous polymer scaffold comprises a plurality of scaffold pores having a scaffold pore volume; and has sub-micron particles incorporated within the scaffold pore volume of the plurality of scaffold pores, and wherein the sub-micron particles are an opaloid within the scaffold pore volume.BRIEF DESCRIPTION OF FIGURES

[0064] The present disclosure will be better understood in view of the following figures. In the figures, identical reference numerals have been used for the same or equivalent features of the composite membrane, supported liquid membrane, and processes disclosed therein. The figures are not necessarily drawn to scale but may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the figures should not be construed as limiting.

[0065] Figure 1 depicts representative scanning electron microscopy images (SEMs) of neat opaloids prepared from 3 different types of silica sub-micron particles with diameters of approximately a) 12 nanometers, b) 22 nanometers, and c) 100 nanometers, respectively;

[0066] Figure 2 is a representative photograph of an opaloid prepared from silica submicron particles having a diameter of approximately 7 nanometers;

[0067] Figure 3a is a schematic depiction of a cross-section of a neat opaloid comprising monodisperse sub-micron particles in a three-dimensional arrangement;

[0068] Figure 3b is a schematic depiction of two adjacent particles, each having a diameter (D) that are elements of a particle packing arrangement within an opaloid as is shown in Figure 3a;

[0069] Figure 4 is a schematic depiction of parameters associated with an opaloid overlaying an SEM of a neat opaloid;

[0070] Figure 5a depicts representative Small-Angle X-ray Scattering (SAXS) data sets for opaloids prepared from silica sub-micron particles having diameters of approximately 7 nanometers, 12 nanometers, 22 nanometers, 45 nanometers, and 100 nanometers;

[0071] Figure 5b is a graphical illustration of inter-particle distance (ID) determined from SAXS data as a function of nominal particle diameter (D) for opaloids prepared from silica submicron particles;

[0072] Figure 6 is a graphical illustration of representative SAXS data for a material comprising aggregates of monodisperse spherical particles, showing the Guinier, fractal, and Porod scattering regimes and an absence of the structure factor peaks characteristic ofP390218USP 3252US01opaloids. This figure was reproduced from Bushell et al. (”On techniques for the measurement of the mass fractal dimension of aggregates,” Advances in Colloid and Interface Science, 95, 1-50 (2002))

[0073] Figure 7 depicts a representative pore size distribution from BET / BJH analysis of an opaloid prepared from silica sub-micron particles having a diameter of approximately 12 nanometers;

[0074] Figure 8 is a schematic depiction of expected values of the ratio of pore diameter to particle diameter (d / D) for different tightly packed arrangements of sub-micron particles where the coordination number, n, is 3, 4, 6, or 8;

[0075] Figure 9a depicts a comparison of specific surface area (SSA) measured by BET with expected particle size;

[0076] Figure 9b is a graphical illustration of a comparison of particle diameter calculated with SSA to the nominal sub-micron particle diameters reported by manufacturers;

[0077] Figure 10a is a schematic illustration of a cross-section of a representative microporous polymer scaffold used in the composite membranes of the present disclosure;

[0078] Figure 10b is a schematic illustration of an opaloid within the representative microporous polymer scaffold of Figure 9a;

[0079] Figure 11 is a schematic illustration of a colloidal dispersion being concentrated to form an opaloid;

[0080] Figure 12 depicts an SEM of a surface view of an opaloid comprising silica submicron particles having a diameter of approximately 22 nanometers in an expanded polytetrafluoroethylene (ePTFE) membrane where the ePTFE membrane had a bubble point of 1.9 bar overlaid with a schematic of parameters associated with a Membrane-Reinforced Opaloid (MRO);

[0081] Figure 13 depicts an SEM of a surface view of a membrane-reinforced opaloid comprising a blend of two populations of sub-micron particles (silica sub-micron particles having a diameter of approximately 7 nanometers and perfluoroalkoxy alkane sub-micron particles having a diameter of approximately 90 nanometers) in an ePTFE microporous polymer scaffold, where the ePTFE had a bubble point of about 1.9 bar.

[0082] Figure 14 depicts an SEM of a surface view of an MRO comprising silica submicron particles with a diameter of approximately 12 nanometers and an ePTFE microporous polymer scaffold where the ePTFE had a bubble point of about 1.9 bar.

[0083] Figure15 is a graphical illustration of SAXS data for a neat opaloid, and an MRO reinforced with an ePTFE microporous polymer scaffold where the ePTFE had a bubble point of 7.6 bar, where both the neat opaloid and the MRO were prepared from an aqueous colloidal dispersion of silica sub-micron particles with a diameter of approximately 12 nanometers;P390218USP 3252US01

[0084] Figure 16 depicts BET / BJH data for four opaloids comprising sub-micron particles with a diameter of approximately 12 nm: neat (i.e., unreinforced), and MROs reinforced with ePTFE microporous polymer scaffolds that had bubble points of 1.9 bar, 4.8 bar, and 7.6 bar, respectively;

[0085] Figure 17a compares two of the data sets from Figure 16 to define,

[0086] Figure 17b depicts <|> plotted against the bubble point pressure for the microporous polymer scaffold for MROs with a sub-micron particle diameter of about 12 nanometers;

[0087] Figure 17c depicts <[> plotted against particle diameter for MROs with a microporous polymer scaffold that had a bubble point of approximately 1.9 bar;

[0088] Figure 18 depicts an SEM of a cross section of an MRO having an opaloid comprising silica sub-micron particles with a diameter of approximately 7 nanometers and an ePTFE microporous polymer scaffold where the ePTFE had a bubble point of about 7.6 bar;

[0089] Figure 19a depicts an SEM of a surface view of an MRO comprising yttria-stabilized zirconia (YSZ) sub-micron particles with particle diameter of about 32 nanometers and an ePTFE microporous polymer scaffold that had a bubble point of about 4.8 bar;

[0090] Figure 19b depicts an SEM of a cross-section of an MRO comprising yttria-stabilized zirconia sub-micron particles with particle diameter of about 32 nanometers and an ePTFE microporous polymer scaffold that had a bubble point of about 4.8 bar;

[0091] Figure 20 depicts an SEM of a surface view of an MRO comprising yttria-stabilized zirconia sub-micron particles with particle size of 32 nanometers in a polyethylene microporous polymer scaffold where the scaffold had a bubble point of about 3.1 bar;

[0092] Figure 21 depicts an SEM of a surface view of a membrane-reinforced opaloid comprising yttria-stabilized zirconia sub-micron particles having a diameter of approximately 32 nanometers in an ePTFE microporous polymer scaffold where the ePTFE had a bubble point of about 3.3 bar;

[0093] Figure 22a depicts representative Small-Angle X-ray Scattering (SAXS) data for a membrane-reinforced opaloid prepared with yttria-stabilized zirconia sub-micron particles having diameter of approximately 32 nanometers; Figure 22b depicts correlation distance -intensity data derived from SAXS for a membrane-reinforced opaloid prepared from yttria-stabilized zirconia sub-micron particles having diameter of approximately 32 nanometers. The triangle indicates a peak position at 19.2 nanometers;

[0094] Figure 23a depicts a sample of an MRO with a high level of transparency sitting on a black lab bench, Figure 23b shows a sample of the material of Figure 19a bent 180° back on itself to illustrate the flexibility of the material, and Figure 23c shows a sample of the same material lying flat on a business card with the words beneath the sample clearly legible with minimal distortion;P390218USP 3252US01

[0095] Figure 24 shows optical haze measurements of three MROs, each comprising silica sub-micron with a diameter of approximately 12 nanometers, and each comprising a different ePTFE microporous polymer scaffold with one of three different bubble points: 1.9, 4.8, or 7.6 bar;

[0096] Figure 25 is a graphical illustration of the capillary flow porometry measurements of three MROs, each comprising silica sub-micron particles with a diameter of approximately 12 nanometers, and each comprising a different ePTFE microporous polymer scaffold with one of three different bubble points: 1.9, 4.8, or 7.6 bar;

[0097] Figure 26 is a schematic depiction of an experimental apparatus for performing Organic Solvent Nanofiltration (OSN);

[0098] Figure 27 is a graphical illustration of the results of Organic Solvent Nanofiltration measurements on three MROs, each comprising silica sub-micron particles with a diameter of approximately 12 nanometers and each comprising a different ePTFE microporous polymer scaffold with one of three different bubble points: 1.9, 4.8, or 7.6 bar;

[0099] Figure 28 is a graphical illustration comparing the measured liquid permeance data to the predicted permeance data for an MRO with a thickness of approximately 2.5 microns comprising silica sub-micron particles with a diameter of approximately 7 nanometers and an ePTFE scaffold that had a bubble point of 7.6 bar;

[0100] Figure 29a depicts a high-pressure flow cell that was used to measure liquid permeance at trans-membrane pressures up to 50 bar, and Figure 29b is a graphical illustration of the resulting liquid flux (in L*m-2*h-1or LMH), and permeance (in LMH / bar) through an MRO having a thickness of about 5 microns and comprising silica sub-micron particles with a diameter of about 7 nanometers and an ePTFE microporous polymer scaffold that had a bubble point of approximately 7.6 bar;

[0101] Figure 30a is a graphical illustration of a tensile measurement in the MD direction of a microporous polymer scaffold and an MRO comprising the microporous polymer scaffold. The MRO had a thickness of approximately 18 microns comprising yttria-stabilized zirconia sub-micron particles with a diameter of approximately 32 nanometers and an ePTFE scaffold that had a bubble point of 3.3 bar and a mass-per-area of 11.6 g / m2. Gauge length was 9.525 mm, Gauge width was 3.175 mm;

[0102] Figure 30b and Figure 30c are a graphical illustrations of tensile measurements in the TD and MD directions, respectively, of a microporous polymer scaffold and an MRO comprising the microporous polymer scaffoldThe MRO had a thickness of approximately 2.5 microns comprising silica sub-micron particles with a diameter of approximately 7 nanometers and an ePTFE scaffold that had a bubble point of 7.6 bar and a mass-per-area of 2 g / m2;P390218USP 3252US01

[0103] Figure 31 is a graphical illustration depicting the relationship between volumespecific pore volume and porosity;

[0104] Figure 32 is a graphical illustration of the calculated relationship between capillary pressure (AP) and pore diameter (d) for cylindrical pores assuming the Young-Laplace equation with a surface tension of 19.75 mN / m and a contact angle of zero degrees;

[0105] Figure 33a shows a schematic cross-section of a vanadium redox flow battery comprising the system of the present disclosure;

[0106] Figure 33b shows a schematic cross-section of a liquid alkaline water electrolyzer comprising the system of the present disclosure;

[0107] Figure 34 shows a schematic of the Force-Displacement-Resistance (FDR) test;

[0108] Figure 35a shows process steps for manufacturing an MRO / PEM Multi-layer Separator for use in a system of the present disclosure;

[0109] Figure 35b shows a cross-section SEM image of an MRO / PEM Multi-layer Separator as produced according to Figure 35a;

[0110] Figure 36a and 36b compare a “Conductance / Shorting” trade-off for three types of separators: MRO Separators, an MRO / PEM Multi-layer Separators, and comparative Reinforced Polymer Electrolyte Membranes;

[0111] Figures 37a and 37b show a surface SEM and a cross-section SEM, respectively, of an MRO porous diaphragm for liquid alkaline water electrolysis comprising yttria-stabilized zirconia sub-micron particles with a particle size of about 32 nm in a microporous polymer scaffold comprised of a copolymer of TFE and PSVE with a bubble point of about 1.3 bar, and Figures 37c and 37d show a surface SEM and a cross-section SEM, respectively, of an MRO porous diaphragm for liquid alkaline water electrolysis comprising yttria-stabilized zirconia sub-micron particles with a particle size of about 32 nm in an ePTFE microporous polymer scaffold with a bubble point of about 3.4 bar;

[0112] Figure 38 shows a cross-section diagram of the high-pressure flow cell shown in Figure 29a that was used to measure liquid permeance at trans-membrane pressures up to 50 bar;

[0113] Figure 39 shows liquid permeance measurements on two MRO porous diaphragms for liquid alkaline water electrolysis, each comprising yttria-stabilized zirconia submicron particles with a diameter of approximately 32 nm, each comprising a different microporous polymer scaffold with bubble points of about 1.3 and 3.4 bar, and compare these samples to a comparative, state-of-the-art LA WE diaphragm;

[0114] Figure 40 shows a schematic of the experimental apparatus for measuring shorting protection for liquid alkaline water electrolysis; and

[0115] Figure 41a shows polarization curve measurements on two MRO porous diaphragms for liquid alkaline water electrolysis, each comprising yttria-stabilized zirconiaP390218USP 3252US01sub-micron particles with a diameter of approximately 32 nm, each comprising a different microporous polymer scaffold with bubble points of about 1.3 and 1.4 bar, and compares these samples to a comparative, state-of-the-art LA WE diaphragm, and Figure 41b shows the ionic resistance estimated from the slopes of the descending polarization curves in the Ohmic regions between 500 and 1000 mA / cm2, corrected for the estimated system resistance.DETAILED DESCRIPTIONDefinitions

[0116] Throughout the description and claims, the terms take the meanings explicitly defined herein, unless the context clearly dictates otherwise.

[0117] The phrases “in one embodiment”, “in an embodiment”, and “in some embodiments” etc. as used herein do not necessarily refer to the same embodiment(s), though they may. Furthermore, the phrases “in another embodiment” and “in some other embodiments” as used herein do not necessarily refer to a different embodiment, though they may All embodiments of the disclosure are intended to be combinable

[0118] The terms “comprises” and “comprising” mean to consist of, consist substantially of, or to include, but are not limited to, such that further features may be present.

[0119] It is to be noted that all ranges described herein are exemplary in nature and include any and all values in between. Measurements that are reasonably close to the stated measurement deviate from the stated measurement by a reasonably small amount as understood and readily ascertained by individuals having ordinary skill in the relevant arts. In the event it is determined that individuals having ordinary skill in the relevant arts would not readily ascertain values for such reasonably small differences, the terms “substantially,” “approximately,” and “about” can be understood to mean plus or minus 10% of the stated value.Introduction to Opaloids including Colloidal Crystals

[0120] Particles, including sub-micron particles and nanoparticles, may be assembled into three-dimensional arrangements with varying packing densities and degrees of order. Examples of such materials may include opaloids and sol-gel solids. Opaloids are solid materials comprising sub-micron particles in tightly packed arrangements where said arrangements have a degree of order that may range from crystalline to nearly amorphous. For illustration, Figure 1 shows representative scanning electron microscopy images of opaloids prepared from 3 different types of silica sub-micron particles with diameters ofP390218USP 3252US01approximately 12 nm, 22 nm, and 100 nm (in Figures 1a, 1b, and 1c, respectively). Figure 2 shows a representative photograph of an opaloid prepared from silica sub-micron particles with a diameter of approximately 7 nanometers. These opaloids were hard, brittle solids as evidenced by the large cracks and chunks evident in Figure 2. The individual chunks could be readily picked up with tweezers and were qualitatively hard like window glass.

[0121] Opaloids may be produced, for example, by producing a stable colloidal dispersion or colloidal suspension (e.g., one in which the colloidal particles are stabilized against aggregation, for example by surface charge on the colloidal particles resulting in DLVO-type repulsion, by polymeric or oligomeric dispersing agents adsorbed on the surfaces of the colloidal particles resulting in steric stabilization, by some combination of these two approaches, or by other colloidal stabilization techniques as will be readily understood by one of ordinary skill in the art) concentrating the stable colloidal dispersion or colloidal suspension through the colloidal glass transition, and substantially drying the material to produce a consolidated solid structure. In contrast, sol-gel solids are solid materials characterized by poorly ordered fractal and aggregate structures. These poorly ordered structures are an inherent result of the gelation dynamics characteristic of sol-gel processes. Such gelation produces aggregates at concentrations below the colloidal glass transition, which prevents the solids from consolidating into the tight, ordered packing arrangements characteristic of opaloids. Therefore, the structure of opaloids is inherently more ordered than that of sol -gel solids. Furthermore, opaloids may have characteristic repeating length scales comparable to the size of the particles, whereas sol-gel solids, if they exhibit any repeating structure at all, may have characteristic repeating length scales comparable to the size of the aggregates. Opaloids and sol-gel solids therefore represent distinct classes of materials. The focus of the present invention is opaloids.

[0122] Opaloids include the widely studied class of materials called “colloidal crystals.” The fabrication and applications of colloidal crystals are discussed extensively in H. Cong et al., “Current status and future developments in preparation and application of colloidal crystals,” Chem. Soc. Rev., 42, 7774 (2013). Cong et al. describe a colloidal crystal as an ordered array or packing of monodisperse colloidal particles. A familiar example of a colloidal crystal is an opal, a naturally occurring gemstone comprising tightly packed arrangements of sub-micron particles of silica that may be highly ordered (e.g., comprising face-centered cubic (fee), and / or hexagonal close packed (hep) structures). For clarity, the term opaloid is inclusive of opals and other colloidal crystals, but is broader. Opaloids may be naturally-occurring or synthetic. Opaloids may comprise packing arrangements of sub-micron particles where the packing arrangements are crystalline, semi-crystalline, and / or nearly amorphous. Non-limiting examples of particle packing arrangements of opaloids include face -centered cubic packing (fee), hexagonal close packing (hep), body-centered cubic (bcc), simple cubic, liquid-likeP390218USP 3252US01packing, as well as arrangements that are substantially similar to the foregoing examples but that may differ, for example, due to structural imperfections or packing defects. Opaloids may be polycrystalline (e.g., they may comprise multiple crystalline or semi-crystalline domains that border each other, and / or that may be separated by nearly amorphous or amorphous domains). Packing arrangements that are polycrystalline or that comprise an intermediate degree of order may optionally be referred to as colloidal semicrystals. The composition of opaloids is not particularly limited (e.g., they may comprise materials other than silica and / or may not comprise silica). However, it is noted that sub-micron particles comprising ceramics and / or glasses may be particularly useful in the present disclosure, e.g., for high thermal stability, high chemical stability, high mechanical stability (e.g., crush resistance), and excellent wettability with various fluids including those with high surface tension. The submicron particles that comprise an opaloid may be essentially monodisperse (e.g., as in the case of a colloidal crystal as described above), but may also be polydisperse because, for example, the high degree of uniformity that may be required to enable highly crystalline order is not required in the case of semi-crystalline or nearly amorphous opaloids. In addition, multiple populations of essentially monodisperse colloidal particles (e.g., 2, 3, or more populations) may by design coexist in the same opaloid. For example, specific size ratios and volume fractions of different monodisperse particles may be combined to enable tight packing in specific crystalline or semi-crystalline arrangements. Examples of such size ratios and volume fractions were described, along with an algorithmic method of predicting them, in “Prediction of binary hard-sphere crystal structures” (L. Filion & M. Dijkstra, Physical Review E, 79, 046714, 2009). The particle size distribution of such an opaloid (e.g., as measured by quantitative image analysis of representative SEM images) may contain multiple peaks (i.e., it may be multi-modal), with each peak corresponding to a population of particles of that characteristic size. Such peaks in the particle size distribution may or may not partially overlap. Such a multi-modal particle size distribution (e.g., as measured by dynamic light scattering) may also be evident in the particle size distribution of the precursor colloid from which the opaloid was produced.

[0123] As another non-limiting example, mixed populations of sub-micron particles may comprise cases where each population of particles comprises different materials (e.g., a population of sub-micron particles of one ceramic blended with a population sub-micron particles of another ceramic, or a population of ceramic sub-micron particles blended with a population of polymer sub-micron particles). In such cases, each population may be substantially monodisperse or polydisperse and the particle sizes of the populations of particles may or may not differ from each other. Such mixed populations of colloidal particles can be prepared, for example, by mixing or blending two or more colloidal dispersions (for example, each corresponding to a substantially monodisperse population of particles) prior toP390218USP 3252US01consolidating the mixed or blended particles into an opaloid. Such colloids and opaloids with mixed or blended particle size distributions may be distinguished from typical polydisperse particle size distributions by the presence of multiple peaks in the particle size distribution (e.g., they may exhibit a multi-modal distribution), and / or they may be present in specific size ratios and volume fractions to enable tight packing in crystalline or semi-crystalline arrangements. The shapes of the sub-micron particles are also not particularly limited, and may include spheres, spheroids, cylinders, and other shapes of both low and high aspect ratio as would be understood by one of ordinary skill in the art.

[0124] For clarity, the term “opaloid” as used herein was derived from the word “opal” and the suffix “-oid,” the latter being chiefly used in science to form nouns with the meaning, “something having the form or appearance of, something related or allied in structure, but not identical’” as described in the Oxford English Dictionary, (updated OED Third Edition, March 2004; most recently modified version published online December 2021, fromwww.oed.com / view / E retrieved June 7, 2023). This noun form of opaloid is readily distinguishable from the rarely used English adjective meaning “resembling an opal in color or appearance” as described in the Oxford English Dictionary, (updated OED Third Edition, March 2004; most recently modified version published online March 2022, from www. oed com / view / Entry / 131683?redirectedFrom=opaloid#ei, retrieved June 7, 2023).

[0125] Opaloids can have many desirable properties, such as a narrow distribution of small pore sizes, relatively high porosity, crush resistance, stability at high temperatures, stability in many chemical environments, wettability with various fluids (including water), and high optical clarity. However, the production of high-quality opaloids for practical applications can be very challenging, particularly for opaloids comprising sub-micron particles comprising ceramics or glass, because of the brittle nature of such materials. For example, significant challenges exist in: 1) fabricating large areas (e.g., areas larger in extent than about one millimeter to several centimeters) with high integrity (i.e., relatively free of through-plane defects such as cracks); 2) making highly flexible, free-standing structures that enable efficient roll-to-roll processing; 3) making mechanically robust structures that can withstand handling, installation, and use in industrial or other applications; and 4) enabling sufficiently rapid fabrication for economical, high-volume production. Accordingly, an object of the present invention is to overcome some or all of these challenges to enable economical production of high-quality opaloids and permit some or all of the advantageous properties of opaloids to be utilized more readily in practical applications.Contrasting the Colloidal Glass Transition and Gelation

[0126] Without wishing to be bound by theory, the characteristic structures and properties of opaloids, as well as the manner in which they differ from other materials such as sol -gelT1P390218USP 3252US01solids, may be clarified through a better understanding of the colloidal glass transition and gelation dynamics for the cases of opaloids and sol-gel solids, respectively.

[0127] Glass transition dynamics enable ordered tight packing of colloidal particles, characteristic of opaloids. Unlike molecular glasses, which may undergo a transition from a liquid to a glass upon cooling, colloidal dispersions or colloidal suspensions may undergo a glass transition upon concentrating (i.e., when the packing density of the dispersed phase within the continuous phase increases to the point that it exceeds a critical threshold). This is the so-called colloidal glass transition, which was described as follows by E. Weeks in “Introduction to the Colloidal Glass Transition,” ACS Macro Lett., 6, 27-34 (2017), “Their glass transition is not as a function of temperature, but rather of concentration. At low concentration, particles undergo Brownian motion and diffuse through the sample freely. At higher concentrations, the particles pack together randomly (with a liquid-like structure), and macroscopically the sample viscosity grows dramatically as a function of concentration. Below the glass transition concentration, Brownian motion enables the sample to equilibrate, and the sample is still considered a liquid. Above the glass transition concentration, equilibration is no longer possible on experimental time scales, and macroscopically the sample has a yield stress like a regular elastic material.” More detailed dynamics of this process were described in “Dynamics of Colloidal Glasses and Gels” (Y. Joshi, Annu. Rev. Chem. Biomol. Eng. 2014.5:181-202), using monodisperse, spherical particles as a case study, “...at low volume fractions (cpv), the suspension is in a fluid state. Upon increasing cpvslowly beyond 0.494, crystals with <pv= 0.545 start nucleating and coexist with the fluid phase. Beyond cpv= 0.545, only the crystalline state exists. With further increases in <pv, the crystals become compact up to cpv“ 0.74, which is the maximum packing fraction associated with the face-centered cubic or hexagonal close packing. If <pvis increased quickly from the fluid state, thereby preventing nucleation of crystals, the suspension enters the so-called supercooled regime. In this regime, individual particles can be considered to be arrested in cages formed by their neighbors. Owing to thermal motion, the particle rattles inside the cage before escaping (diffusing). This cage-diffusion timescale, also known as a relaxation time (TQ), increases with <pvand diverges as cpv— 0.58, the concentration associated with the colloidal glass transition. Monodispersed spherical particles can exist in the random disordered configuration up to only <pv= <prcp~ 0.64, the random close-packing fraction. cprcpincreases with polydispersity. The elasticity of particulate glasses originates in caging...” The Joshi reference further states, “For spherical particles with hard-sphere interactions, MCT [mode coupling theory] predicts an ideal glass transition at the volume fraction of 0.525.” Note that the volume fractions of particles stated in the quote from the Joshi reference were specific to the case study being examined, and these particle volume fractions may differ for other colloidal systems due to, for example, particles with different shapes or degrees of stabilization. For example, the volume fractionP390218USP 3252US01associated with the colloidal glass transition may be about 0.4, or about 0.45, or about 0.49, or about 0.5, or about 0.55, or about 0.58, or about 0.60, or about 0.65, or about 0.7, or about 0.75, or about 0.8, or about 0.85. The importance of the colloidal glass transition as the dividing line between low and high solids concentrations, the former of which requires long-range structures (e.g., gels) for rigidity, and the latter of which does not, was further clarified in “Colloidal Gelation” (Del Gado et al., Chapter 14 of Fluids, Colloids and Soft Materials: An Introduction to Soft Matter Physics, First Edition. Edited by Alberto Fernandez Nieves and Antonio Manuel Puertas.© 2016 John Wiley & Sons, Inc. Published 2016 by John Wiley & Sons, Inc.), where the authors note that, “At larger concentrations, the formation of spacespanning networks is no longer a requirement for rigidity” and that above the colloidal glass transition, “the constituent of the system is permanently trapped in cages of nearest neighbors.” In summary, the foregoing passages describe the colloidal glass transition in detail and illustrate how it enables colloidal particles to consolidate into tightly packed structures (e.g., those in which the volume fractions of the constituent particles are greater than about 0.4) with high degrees of order, characteristic of opaloids.

[0128] In contrast, sol-gel processes are characterized by gelation dynamics. As described in “Colloidal Sol-Gel: A powerful, low-temperature aqueous synthesis route of nanosized powders and suspensions" (Open Ceramics 8, 100200 (2021)), a “sol” is a colloidal system comprising a discontinuous solid phase dispersed in a continuous liquid phase. Sols are typically produced through the hydrolysis of a precursor comprising a metal atom surrounded by ligands that do not contain metal. Depending on the hydrolysis conditions, the solid phase of the resulting sols may be categorized as either fine particles or polymerized molecules (e.g., oligomers), resulting in either a colloidal sol or polymeric sol, respectively, with the latter being significantly more common in the art. Upon gelation (i.e., the “gel” transition step in the sol-gel process) the solid phase forms a network with long-range structure leading to a gel that typically has high viscosity and may be described as comprising a solid phase and a liquid phase that are co-continuous. Gelation occurs at low concentrations (i.e., below the colloidal glass transition, most typically far below it, e.g., as illustrated by the extremely high porosity characteristic of silica aerogels) and is usually induced through chemical means (e.g., through neutralization of surface charges in the sol), resulting in particle gelation and aggregation, as well as poorly-ordered fractal and aggregate structures. As described by Schmidt (Journal of Non-Crystalline Solids 100 (1998) 51-64.), " For stable colloids (which in general remain stable due to the surface charge of their colloidal particles) the neutralization of surface charges (isoelectric point) leads to gelation, including the following basic reactions: neutralisation of surface charges, aggregation, further condensation by reactive surface groups, gelation (accompanied by a strong viscosity increase) to a solid gel." The poor degree of order of fractal gel structures and methods of characterizing the structureP390218USP 3252US01are well-established in the literature, for example, by Sinko et al. (Journal of Non-Crystalline Solids 354 (2008) 5466-5474), “The structure of ill-ordered materials, such as amorphous glasses, fractal systems, or aggregate structures is difficult to describe in direct pictures, these structures can well be characterized by scattering experiments.” The authors further describe how “The aggregate structure defines a random packing of colloidal particles.” In summary, the foregoing passages describe the gelation dynamics of the sol-gel process in detail and illustrate how they result in poorly ordered fractal and aggregate structures characteristic of sol-gel solids.

[0129] Well-ordered opaloids (e.g., those comprising sub-micron particles that have gone through a colloidal glass transition), and sol-gel materials with a fractal structure can be further distinguished by their characteristic length scale. Opaloids exhibit repeating order on the length scale of individual particles and may show a narrow distribution of inter-particle distances, whereas sol-gel structures may exhibit repeating order on the aggregate length scale. This distinction is described in the following passage from “Dynamics of Colloidal Glasses and Gels” (Y. Joshi, Annu. Rev. Chem. Biomol. Eng. 2014. 5:181-202), "... the colloidal glassy and gel state can be distinguished based on the length scale beyond which the density becomes homogeneous. In particulate colloidal glasses [including e.g., opaloids), this length scale is close to the inter-particle distance, whereas in gels it is approximately the aggregate length scale."

[0130] Due substantially to the gelation dynamics described above, sol-gel processes and the resulting sol-gel solids have several drawbacks that limit their utility. Secondary structure formed during the gelation process can limit the dynamics of packing, producing irregular and polydisperse void structures. Bonding or sintering between particles can result in brittle or inflexible materials, limiting the toughness or durability of produced articles. Porosity may become limited as additional precursor converts to solid during the gelation phase. Furthermore, sol-gel solids, being based primarily on hydrolyzable precursors as described above, represent a narrower set of materials than opaloids, which encompass but are not limited to the full gamut of ceramics and glasses. Sol-gel chemistry can also impose significant complexity as well as onerous time constraints on industrial manufacturing processes such as roll-to-roll manufacturing processes. It is an object of the present invention to overcome these deficiencies by developing improved materials and processes based on opaloids.

[0131] Although concentrating a colloidal dispersion or colloidal suspension through the colloidal glass transition may be a preferred element of a process for fabricating opaloids, opaloids are not particularly restricted in their method of manufacture. If the appropriate arrangement of sub-micron particles (e.g., as described above in the Introduction to Opaloids Including Colloidal Crystals) can be made without the use of a colloidal dispersion or colloidal suspension, it may nevertheless be considered an opaloid as defined herein.P390218USP 3252US01

[0132] For clarity, the use of the term “colloidal” may be interpreted depending on the context according to both meanings described in Slomkowski et al., “Terminology of polymers and polymerization processes in dispersed systems (IUPAC Recommendations 2011)*” Pure Appl. Chem., Vol. 83, No. 12, pp. 2229-2259 (2011): a “state of subdivision such that the molecules or polymolecular particles dispersed in a medium have at least one dimension between approximately 1 nm and 1 pm, or that in a system discontinuities are found at distances of that order.” Consistent with the first part of this definition (the two parts of the definition being separated by a comma), the term “colloidal” in “colloidal dispersion” or “colloidal suspension” may be interpreted as comprising particles dispersed in a medium in which the particles are within the characteristic length scale from approximately 1 nm to approximately 1 pm in size. Consistent with the second part of this definition, the term “colloidal” as used in “colloidal crystal” or “colloidal semi-crystal” may be interpreted as comprising sub-micron particles (e.g., nanoparticles) that are approximately 1 nm to approximately 1 pm in size, and / or as indicating that the inter- particle distances (ID) and / or pore sizes (d) of opaloids are also typically in this size range.

[0133] The term “colloidal glass” can be interpreted according to both parts of Slomkowski’s definition of “colloidal” quoted above. Consistent with the first part of Slomkowski’s definition, the term “colloidal glass” in the scientific literature typically refers to a colloidal dispersion or colloidal suspension that has undergone a colloidal glass transition and exhibits highly viscous, glass-like behavior as described by Weeks as quoted above, “macroscopically the sample viscosity grows dramatically as a function of concentration. Below the glass transition concentration, Brownian motion enables the sample to equilibrate, and the sample is still considered a liquid. Above the glass transition concentration, equilibration is no longer possible on experimental time scales, and macroscopically the sample has a yield stress like a regular elastic material.” However, the term colloidal glass can also be interpreted according to the second part of Slomkowski’s definition, meaning the sub-micron particles (including nanoparticles) of colloidal glasses are typically 1 nm to 1 pm in size, and the inter-particle distances (ID) and / or pore sizes (d) of colloidal glasses are also typically in this size range. Thus, the term “colloidal glass” does not necessarily imply that the particles are dispersed or suspended in a fluid. Instead, it can refer more broadly to tightly packed arrangements of sub-micron particles that retain features or discontinuities on the colloidal length scale. It may also be interpreted as an acknowledgement that such arrangements of sub-micron particles are usually produced from a precursor that was itself a colloidal dispersion or colloidal suspension. The opaloids described in the present disclosure may therefore be considered a form of colloidal glass. However, for clarity, the inventors prefer the term “opaloid” to “colloidal glass” as a term to describe the broad class of materials that is the focus of the present disclosure.P390218USP 3252US01Detailed Description of Neat Opaloid Morphology and Properties

[0134] This section will establish basic nomenclature for describing opaloid structures without mechanical reinforcement Such opaloids without mechanical reinforcement (e.g., without an integrated microporous polymer scaffold) may also be called “neat” opaloids. Material properties of neat opaloids will also be discussed.

[0135] Figure 3a shows a schematic of a cross-section of a neat opaloid 9 comprising monodisperse sub-micron particles 10 in a three-dimensional arrangement. The sub-micron particles in Figure 3a are depicted as having a high degree of order (e.g., a substantially facecentered cubic arrangement), but as described above other packing arrangements are possible, for example more amorphous arrangements such as liquid-like packing. The neat opaloid may comprise large defects (e.g., cracks) 11 that extend through the entire thickness of the opaloid, and may comprise other defects (e.g., cracks) 12 that do not extend through the entire thickness.

[0136] As described above, opaloids comprise tightly packed three-dimensional arrangements of sub-micron particles. Figure 3b shows two adjacent particles of diameter D that are elements of a particle packing arrangement within an opaloid. The tightness of the packing arrangement may be described by the inter- particle distance (ID, typically expressed in units of nanometers), which is the distance between the centers of adjacent sub-micron particles (or if the particles are non-spherical, then between the centroids of adjacent particles). Inter-particle distance may be considered a population property that is inherently polydisperse and may be described by an ID distribution. In an opaloid, the ID may be of colloidal size. Further, the ID of two adjacent particles may be approximately the particle diameter D (note that for polydisperse particles the effective D is the sum of the radii of the two adjacent particles, and if a particle is irregularly shaped then its effective radius is the radius of a sphere that occupies the same volume, and analogously its effective diameter is the diameter of a sphere that occupies the same volume). However, even in a tightly packed arrangement the distance between two adjacent particles may be smaller or larger than the sum of their radii. Said distance may be smaller, for example, because particles with irregular shapes may enable tighter packing. Said distance may be larger, for example, because submicron particles in the opaloid may not pack in perfect crystalline arrangements or because they may be coated in a material such as a polymeric material (e.g., a dispersing agent). The ID may be, for example, greater than about 0.5 times the effective particle diameter D and less than about 3 times the effective particle diameter D. The ID may be, for example, greater than about 0.5 times the effective particle diameter D and less than about 2.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.5 times theP390218USP 3252US01effective particle diameter D and less than about 2 times the effective particle diameter D. In some examples, the amount of material (e.g., polymeric material) between adjacent particles may be minimized or eliminated. In the latter case, for example, the sub-micron particles may have direct contact with each other. The opaloid may substantially lack an organic binding agent (e.g., a polymeric binder). The opaloid may comprise sub-micron particles that are bonded together substantially by van der Waals forces, by inorganic bonds, or by a combination of the two.

[0137] The inter-particle distance may be determined via microscopy in combination with Quantitative Image Analysis, for example using the method depicted on the scanning electron micrograph in Figure 4. As indicated by the subscripts in the figure (i.e., Dnand IDn), a sufficient number of particles (to measure D) and pairs of adjacent particles (to measure ID) may be analyzed to generate representative statistics for the opaloid. In the case of irregular particles, ID may be calculated as the average distance between adjacent particle centroids. To obtain a high-quality microscopy image, the conditions must be appropriately tailored to the specific sample being examined (e.g., appropriate magnification, working distance, accelerating voltage, etc.). The practice of tailoring such observing conditions is well-known to those of ordinary skill in the art. Quantitative Image Analysis may be used for determining ID when the inter-particle distance is larger than about 80 nm or larger than about 100 nm. If the inter-particle distances are less than about 100 nm or less than about 80 nm, then Small Angle X-ray Scattering (SAXS) may be used to determine the inter-particle distance. Figure 5a shows representative SAXS data sets for neat opaloids prepared with 5 different types of silica sub-micron particles with diameters of approximately 7 nm, 12 nm, 22 nm, 45 nm, and 100 nm. The peaks in the SAXS data are identified with triangles and correspond to structures of a given length scale, typically from 0.5 nm to 80 nm. For these data, peaks indicate nanoscale organization of particles (spherical in this case) and are observable due to the contrast between SiO2 and pores (vacuum). The peaks can be referred to as structure factor peaks. Peak positions are given by the scattering vector, q, and the average center-to-center inter-particle distance, ID, is obtained from the position of the primary peak, q₁, or lowest q-value peak: ID = 2π / q₁. As shown in Figure 5b, there is reasonable agreement between nominal particle diameters (D) and the inter- particle distance (ID) values determined by SAXS for neat (i.e. non-reinforced) packing arrangements of SiO2 sub-micron particles. The dashed line in Figure 5b is the 45° line passing through the origin and is included as a guide to the eye. For 7 nm and 45 nm silica sub-micron particle opaloids, weak, broad peaks indicate a more disordered structure and broader distribution of center-to-center IDs compared to the other data in the chart. A weak higher order feature was observed, but it is difficult to determine the peak position or assign the scattering profile to cubic or close-packed morphology. In contrast, opaloids with 12, 22, and 100 nm silica sub-micron particles exhibitedP390218USP 3252US01narrow peaks, corresponding to a narrow distribution of IDs. Narrow peaks also indicate greater long-range order, where particles exhibit more uniform symmetry over length scales greater than the nearest neighbors. Multiple higher order peaks may also signify long-range order. Higher order peaks may also result from larger particles and inter-particle distances, which shift the scattering pattern to lower q and allow higher order peaks to be detected within the instrument’s range. Higher-order scattering peaks are characterized by peak positions 92, 93,... qn. The packing arrangement can be deduced by comparing SAXS peak position ratios, q₂ / q₁: q₃ / q₁:... qₙ / q₁, to characteristic values for specific arrangements, where qncorresponds to the positions of the higher order peaks. Peak position ratios for common spherical packing geometries may include 1: 1.41: 1.73: 2.00: 2.24: 2.45: 2.83 (simple cubic packing), 1: 1.41: 1.73: 2.00: 2.24: 2.45: 2.65 (body-centered cubic packing), 1: 1.15: 1.63: 1.91: 2.00: 2.31: 2.52: 2.58: 2.83: 3.00 (face-centered cubic packing), or 1: 1.06: 1.13: 1.46: 1.73: 1.87: 1.92 (hexagonal close packing). In Figure 5a, peaks are observed at peak position ratios q₁ / q₁: q₂ / q₁: q₃ / q₁:... qₙ / q₁ of 1: 1.64: 2.34, 1: 1.67: 2.43, and 1: 1.70: 2.50: 3.28: 4.04: 4.81, for neat opaloids with 12, 22, and 100 nm silica sub-micron particles, respectively. The SAXS peak position ratios are consistent with having substantially close-packed arrangements; however, deviations from reported peak position ratios indicate that these neat opaloids do not exhibit perfect crystalline order. Deviations from expected values may be due to, for example, packing defects or polydispersity. A given observed peak position ratio may be within about 1%, or within about 2 %, or within about 3 %, or within about 4 %, or within about 5% of the nearest characteristic peak position ratio and certain peak position ratios may not be observed, for example depending on the form factor scattering of the sub-micron particles.

[0138] Structure factor peaks may be identified in the Lorentz-corrected data (intensity*q2) as will be understood by one of ordinary skill in the art. Opaloids may be characterized by the presence of 1 or more structure factor peaks in the SAXS data, or by the presence of 2 or more structure factor peaks in the SAXS data, or by the presence of 3 or more structure factor peaks in the SAXS data, or by the presence of 4 or more structure factor peaks in the SAXS data, or by the presence of 5 or more structure factor peaks in the SAXS data, or by the presence of from 1 to 5 structure factor peaks in the SAXS data, or by the presence of from 1 to 10 structure factor peaks in the SAXS data, or by the presence of from 2 to 5 structure factor peaks in the SAXS data, or by the presence of from 2 to 10 structure factor peaks in the SAXS data. For a material to be considered an opaloid, it is not required that the peak position ratios for the structure factor peaks correspond to the theoretical peak position ratios for known arrangements of particles. In contrast, the SAXS data depicted in Figure 6, which was reproduced from Bushell et al. (”On techniques for the measurement of the mass fractal dimension of aggregates,” Advances in Colloid and Interface Science, 95, 1-50 (2002)), showsP390218USP 3252US01an absence of the structure factor peaks characteristic of opaloids. Instead, it shows representative SAXS data for a material comprising aggregates of monodisperse spherical particles, illustrating the Guinier, Fractal, and Porod scattering regimes. These data are characteristic of the poorly ordered fractal and aggregate structures characteristic of sol-gel solids. When analyzing SAXS data, care must be taken not to misinterpret the features shown in Figure 6, such as the “knee” at the transition between the Guinier regime and the Fractal regime, or the q-4dependence of the scattering intensity in the Porod regime, as structure factor peaks. As described above, structure factor peaks may be preferably identified in the Lorentz-corrected data (intensity*q2).

[0139] The spaces between and among the sub-micron particles in an opaloid (i.e., the inter-particle pores, collectively the inter-particle pore volume, typically expressed in units of cc / g or as a porosity in vol%) may define an interconnected pore volume that is characteristic of the opaloid. Figure 3a shows a schematic of a cross-section of a neat opaloid comprising monodisperse sub-micron particles 10 in a three-dimensional packing arrangement, having an inter- particle pore volume 13. The pore volume 13 may have a complex and / or irregular geometry. The challenge of quantitatively characterizing the pore size of porous materials with complex or irregular pore geometries is well-known. Pore size in this case may be considered a population property that is inherently polydisperse and may be described by a pore size distribution. A variety of standard evaluation methods are available to those of ordinary skill in the art, such as quantitative image analysis, BET / BJH analysis, capillary flow porometry (including bubble point analysis), liquid / liquid porometry, thermoporometry by differential scanning calorimetry, and mercury porosimetry. Each of these quantification methods makes simplifying assumptions about the pore geometry, and most produce a pore size distribution from which characteristic pore size parameters may be extracted, such as a median or mode pore size (via BET / BJH analysis), the largest through-pore (e.g., via bubble point determination), or the mean flow pore size (via capillary flow porometry). In some embodiments, the mode pore size(s) of opaloids may be characterized via BET / BJH analysis as a preferred method. Figure 7 shows a representative pore size distribution from BET / BJH analysis of a neat opaloid prepared from silica sub-micron particles with a diameter of approximately 12 nm. The mode pore size of the distribution shown in Figure 7 is approximately 5 nm. The three-dimensional packing arrangement of the neat opaloid may be further characterized by comparing the pore diameter (d) to the particle diameter (D), for example using the ratio d / D. Figure 8 shows the expected values of d / D for different tightly packed arrangements with different coordination numbers (n). For many opaloid packing arrangements, the pore diameter is expected to be smaller than the particle diameter (i.e., d / D < 1). However, for the same reasons that the ID may be larger than D, d / D may be larger than 1, for example the opaloid may have d / D < 1.1 or d / D < 1.5 or d / D < 2.0.P390218USP 3252US01

[0140] The challenge of characterizing the particle size (e.g., the particle diameter, D) of the sub-micron particles in an opaloid is also complex and well-known to those of ordinary skill in the art. A variety of standard tools are available, such as dynamic light scattering of the colloidal dispersion from which the opaloid is produced (in which case care must be taken to prevent agglomeration from skewing the data), or direct microscopy of the opaloid itself, such as in Figure 4. In the case of particles of known shape (e.g., spherical particles), and known level of surface roughness (e.g., essentially smooth), the specific surface area (SSA, in units of m2 / g, as measured by BET) may be measured, and if the density of the particles (p) is known (or if it can be measured, for example by helium pycnometry), then a representative particle size may be calculated using, for example, the standard equations for the volume and area of a sphere (Vsphereand Asphere, respectively) based on its diameter (D). The relevant equations for a sphere are as follows:A_sphere = πD²πD³V_sphere =πD³ / 6SSA = A_sphere / V_sphere × (1 / ρ)ρ·(πD³ / 6)6D = 6 / ((SSA)·ρ)Figure 9 illustrates how SSA may be used to estimate the particle size of an opaloid. Five neat opaloids were produced from solid silica sub-micron particles with nominal diameters (as reported by the manufacturers) of 7 nm, 12 nm, 22 nm, 45 nm, and 100 nm. Figure 9a compares the SSA measured by BET (solid dots) to the expected values (open squares). The expected values were calculated assuming the sub-micron particles are perfectly smooth, solid spheres of the nominal diameter and assuming a density of silica of 2.2 g / cc. Figure 9b compares the particle diameter calculated from the SSA data to the nominal diameters reported by the manufacturers. The dashed line in Figure 9b is the 45° line passing through the origin and is included as a guide to the eye. As shown in Figure 9b, the SSA method for determining particle size works well for particles that are essentially smooth, solid spheres and may be utilized in such relatively simple cases. However, this method may not be as accurate for particles with a large degree of internal porosity or high surface roughness. In such complex cases characterizing the particle size of the constituent sub-micron particles in an opaloid may be done with direct observation via scanning electron microscopy, which may be combined with quantitative image analysis. The calculations described in the foregoing paragraph, and illustrated in Figure 9, may be used to calculate the effective diameter of the sub-micron particles of the opaloid. In the case that the sub-micron particles contain intra-P390218USP 3252US01particle pores, then the density to be used in the calculation is the sub-micron particle apparent density. The sub-micron particle apparent density is the matrix density of the particle multiplied by the packing fraction of the sub-micron particle).

[0141] In the description of opaloid morphology above, many of the properties may be considered population properties, such as inter- particle distance (ID), pore diameter (d), and particle diameter (D). Such properties may be represented by distributions, which may be characterized using standard summary statistics known to those of ordinary skill in the art. Such summary statistics include the median value, the volume-weighted mode value, the volume-weighted average, the number-weighted mode value, the number-weighted average, and the related 10 / 25 / 75 / 90 percentile values. When comparing two different population properties (for example, when comparing pore diameter to particle diameter), consistent summary statistics may be used (for example, making the comparison using the mode value for both properties). In some cases, the volume-weighted mode value may be preferred.Advantages and Challenges of Opaloids

[0142] As described above, opaloids may have many advantageous properties, especially when the opaloid comprises sub-micron particles (including nanoparticles) that themselves comprise ceramics or glass. Such properties may include:1. Narrow distribution of small pore sizes (e.g., comprising the spaces between adjacent sub-micron particles, and optionally porosity within sub-micron particles) 2. Relatively high porosity, especially considering their small pore size (e.g., porosity of around 30 vol% - 70 vol%, due to the packing arrangement of the constituent sub-micron particles)3. Crush-resistance, enabling porosity to be retained even under mechanical compression4. Stability at high temperatures (e.g., including dimensional stability due to the tight packing and temperature stability of the constituent sub-micron particles) 5. Stability in a wide range of chemical environments (e.g., due to the chemical properties of the constituent sub-micron particles)6. Wettability with various fluids including water (e.g., due to the wettability of the constituent sub-micron particles)

[0143] However, practical and high-integrity opaloids are very challenging to produce. Significant challenges include:a. Fabricating large areas with high integrity (e.g., relatively free or free of through- plane defects such as cracks). In this case, “large areas” means larger than between 1 millimeter or a few centimeters in extent in each of two orthogonalP390218USP 3252US01directions, and “through-plane defects” can be characterized as through-plane cracks or holes that compromise the integrity of the opaloid and contribute to it having e.g., greater haze, a much lower bubble point, higher liquid or gas permeance, and / or poorer ability to selectively remove small species via filtration. b. Making flexible, free-standing structures that enable e.g., industrial roll-to-roll processing. Bending stiffness may be quantified by e.g., a Kawabata bend test. Furthermore, flexibility may also be evaluated by wrapping the composite membrane around a mandrel of defined diameter, then unwrapping the composite membrane, repeating these cycles of wrapping and unwrapping a desired number of times, and then using a performance test to evaluate the suitability of the composite membrane for the desired application. A non-limiting example of such a performance test is the Organic Solvent Nanofiltration (OSN) test described below. c. Making mechanically robust structures that can withstand shipping, handling, storage, installation, and operation in the intended application, especially when the opaloid is very thin. Tensile testing may be used, for example, to evaluate mechanical robustness.d. Enabling sufficiently rapid fabrication (e.g., coating and drying times of a few minutes or less, for example less than 1 minute) for e.g., economical, high-volume production (e.g., thousands of square meters per year, hundreds of thousands of square meters per year, millions of square meters per year, billions of square meters per year, or more).Introduction to Membrane-Reinforced Opaloids

[0144] The inventors have surprisingly discovered that some or all of the aforementioned challenges a - d can be overcome, while simultaneously retaining some or all of the aforementioned advantageous properties 1 - 6, by producing composite membranes in which an opaloid is reinforced with a microporous polymer scaffold. Figure 10a shows a schematic of a microporous polymer scaffold 14, for example ePTFE, comprising scaffold matrix 15, for example nodes interconnected by fibrils, and scaffold pores 16. As illustrated in Figure 10b, the inventors have shown that opaloid 9 comprising sub-micron particles 10 and inter- particle pores 13 can be formed within the scaffold pores 16 of the microporous polymer scaffold to form composite membranes 20 of the present disclosure. Such composite membranes may be referred to as Membrane-Reinforced Opaloids (MROs). Figure 10b further shows that the MROs (i.e., the composite membranes 20) comprise composite membrane pores 22, which comprise inter- particle pores 13 of the opaloid 9 within the scaffold pores 16, and interfacial particle-scaffold pores 24 (i.e., pores whose boundaries are defined by both the structuralP390218USP 3252US01elements of the scaffold and the constituent particles of the opaloid; in practice these are pores at the interface between the opaloid and the scaffold matrix). Additionally, cracks or defects 26 may be present. In an MRO, an opaloid may fill at least a portion of the pore volume of a microporous polymer scaffold. The opaloid may comprise a continuous opaloid phase (e.g., with a continuous pore volume defined by the inter- particle pores) that extends over a large area (meaning larger than between 1 millimeter or a few centimeters in extent in each of two orthogonal directions) within the pore volume of the microporous polymer scaffold.

[0145] Further, the inventors have surprisingly discovered that the quality of MROs may be dramatically improved when the MROs comprise a microporous polymer scaffold characterized by extremely tight pores (i.e., a microporous polymer scaffold with a bubble point of greater than about 2 bar). Such MROs may be referred to as High-Integrity MROs. In High-Integrity MROs, cracks or defects 26 (as shown in Fig. 10) can be minimized or eliminated. The minimization or elimination of such cracks or defects may be demonstrated, for example, using capillary flow porometry of the MRO and / or direct visualization of the MRO via microscopy such as scanning electron microscopy, as will be shown below.

[0146] The production of MROs with high integrity and high quality via the use of membrane reinforcements with extremely tight pores was surprising in numerous respects:1. The extremely tight structure and high surface area of the microporous polymer scaffold provided a large number of potential nucleation sites for defects within the opaloid. Nevertheless, through-plane defects (e.g., cracks) were surprisingly minimized (e.g., as measured by capillary flow porometry).

[0147] The extremely tight structure and high surface area of the microporous polymer scaffold also provided a large number of interfaces with the potential to disrupt the formation and structure of the opaloid. Nevertheless, the MROs surprisingly and substantially retained both the narrow distribution of small pores (e.g., as measured by BET / BJH), and the tight particle packing arrangement (e.g., as measured by SAXS) associated with the neat opaloid.

[0148] The rapid drying of the MROs under hot-air convection (e.g., in a few minutes or less, consistent with the needs of high-volume production), imposed turbulent surface forces and significant mechanical stresses on the MRO. Nevertheless, defects were surprisingly minimized (e.g., as measured by capillary flow porometry, BET / BJH, SAXS, and haze), and there was no obvious loss of particles during drying or subsequent handling despite the absence of a binder (e.g., a polymeric binder).2. The extremely tight structure and high surface area of the microporous polymer scaffold provided a high-surface-area matrix of hydrophobic material throughoutP390218USP 3252US01the composite membrane. Nevertheless, the resulting MROs were surprisingly highly wettable with water.3. The extremely tight structure and high surface area of the microporous polymer scaffold provided a large number of interfaces to nucleate defects during mechanical stress testing, and the lack of a binder provided limited support to cohere the particles. Nevertheless, the resulting MROs were flexible and freestanding and able to survive significant handling and mechanical stress without significant loss of particles or desirable properties. In addition, the MROs showed exceptional robustness when subjected to liquid flow under very high transmembrane pressures up to about 50 bar with no obvious change in liquid permeance after exposure to such high pressures.4. The use of reinforcements with extremely tight structures surprisingly produced a “step change” in the ability of the MROs to selectively separate small molecules from a solvent (e.g., as measured through organic solvent nanofiltration).As described above, both the sub-micron particles and the microporous polymer scaffolds are main elements of the membrane-reinforced opaloids of the present invention. These elements will be described in greater detail in the next two sections.Description of Sub-micron Particles

[0149] The following description of the sub-micron particles is applicable to all embodiments, examples and aspects of the composite membranes, systems for use as electrochemical separators, electrochemical devices, supported liquid membranes and methods described herein. The sub-micron particles within the plurality of scaffold pores may be substantially monodisperse in size. The sub-micron particles may comprise a mixture of substantially monodisperse populations (e.g., resulting in a multi-modal pore size distribution). As used herein, the term population may be used to refer to sub-groups within the sub-micron particles, for example sub-micron particles having different sizes within a population having otherwise about the same materials, and / or shape, and / or source within the supply chain. Alternatively, populations may be used, for example, to refer to sub-groups having different sizes, and / or materials, and / or shape, and / or source within the supply chain.

[0150] The sub-micron particles may have a particle diameter (or effective particle diameter) of about 1 nm to about 1 pm. Therefore, the term sub-micron particle is also intended to include nanoparticles, where nanoparticles are particles typically comprising a particle diameter (or effective diameter) of about 1 nm to about 100 nm. The sub-micron particles may have a particle diameter (or effective particle diameter) of about 1 nm to 500 nm (noting thatP390218USP 3252US01the term “about” applies to both the bottom and top of the range), or about 1 nm to about 200 nm, or about 10 nm to 500 nm, or about 1 nm to 100 nm, or about 1 nm to 80 nm, or about 5 nm to 70 nm, or about 4 nm to 50 nm, or about 5 nm to 50 nm, or about 5 nm to 75 nm, or about 2 nm to 60 nm, or about 2 nm to 50 nm, or about 2 nm to 25 nm. The sub-micron particles may have a particle diameter (or effective particle diameter) of up to and including 45 nm, or up to and including 25 nm, or up to and including 15 nm, or up to and including 10 nm, or up to and including 8 nm. Without wishing to be bound by theory, it is hypothesized that larger particles may result in weaker drying forces, and therefore tighter (higher bubble point pressure) microporous polymer scaffolds may not necessarily be required to prevent defects (e.g., cracks) within the composite membrane during fabrication when such particles are used.

[0151] The sub-micron particles may comprise at least two different populations of submicron particles, where a first population of sub-micron particles is characterized by a first particle diameter (or effective particle diameter) and a second population of sub-micron particles is characterized by a second particle diameter (or effective diameter). The first and second particle diameters (or effective diameters) may be the same, or the first and second particle diameters (or effective diameters) may be different. In the case where different populations of sub-micron particles have different diameters (or effective diameters), the particle size distributions may be multi-modal, where each population with a different diameter corresponds to a peak in the distribution.

[0152] As used herein, the particle diameter is taken to mean the particle diameter as measured by the test methods described herein. It is also intended to encompass non-spherical particles, where such particles may be regarded as having an effective particle diameter. As used herein, the effective particle diameter is the diameter of a hypothetical spherical particle of same composition that, using a given particle-size determination method, would give the same diameter as a substance composed of spherical or non-spherical particles at the same concentration.

[0153] The sub-micron particles are not intended to be limited to a particular shape and may include sub-micron particles of any shape as required for the composite membranes’ intended purpose. The sub-micron particles may be substantially spherical in shape. The submicron particles may have a polygonal structure. The sub-micron particles may have an aspect ratio of about 1, or of about 1.2, or of about 1.4, or of about 1.6, or of about 2, or of about 2.5, or of about 3.

[0154] The sub-micron particles may be porous or non-porous. The sub-micron particles may be hydrophilic or hydrophobic. The sub-micron particles may be oleophilic or oleophobic.P390218USP 3252US01

[0155] The sub-micron particles may be stable (e.g., may be practically insoluble) at very high pH (e.g., above about pH 10, or above about pH 11, or above about pH 12, or above about pH 13, or above about pH 14). The sub-micron particles may be stable (e.g., may be relatively insoluble) at very low pH (e.g., below about pH 5, or below about pH 4, or below about pH 3, or below about pH 2, or below about pH 1, or below about pH 0).

[0156] The sub-micron particles may comprise a wide variety of materials including ceramics and glasses (noting that some common definitions of ceramics include glasses as a subset of ceramics). Sudha et al. describe ceramics as follows in “Corrosion of ceramic materials” (in Fundamental Biomaterials: Ceramics, Editor(s): Sabu Thomas, Preetha Balakrishnan, M. S. Sreekala, Woodhead Publishing Series in Biomaterials, Woodhead Publishing, 2018, Pages 223-250), “Ceramics materials can be defined as inorganic, nonmetallic materials comprising metal, nonmetal, or metalloid atoms held by ionic or covalent bonds. The ceramic structure is based on electric neutrality. They are generally prepared using clays and other minerals from the earth or chemically processed crystalline oxide, nitride, or carbide powders, i.e., aluminium and oxygen (alumina — Al₂O₃), silicon and nitrogen (silicon nitride — Si₃N₄, silicon and carbon (silicon carbide — SiC), etc. Ceramic materials are typically categorized as traditional ceramic and advanced ceramic. Traditional ceramic materials include clay, porcelain, feldspar, silica, calcite, and nepheline... Advanced ceramics includes alumina, zirconia, silicon carbide, silicon nitride, and titania-based materials, which can replace the metals and plastics in the modern era due to their exceptional properties that make them highly resistant to melting, bending, stretching and possess unique individual properties in their own way... Ceramic materials are broadly classified into two types based on the arrangement of atoms that constitute the particular substance, (a) Crystalline ceramic materials: Most of the ceramic materials have crystalline structure and are more brittle than metals. The arrangement of atoms in the crystalline ceramic was highly ordered throughout the material. Crystalline ceramics were not amenable to set of processing / production. These materials were generally synthesized either by compacting powders into a body followed by sintering at higher temperature to form a solid desired shape or by the reaction “in situ.” The techniques adapted to form crystalline ceramics include slip casting, tape casting, injection molding, dry pressing, and so on. (b) Noncrystalline / Amorphous ceramic materials: The processing of glass is totally different from the crystalline ceramic preparation and involves several steps. Noncrystalline ceramic, being glasses, can be usually prepared from melts. The glasses were processed into desired shape either by casting them in the molten state or by blowing the toffee-like viscosity state into a mold. These noncrystalline ceramic materials were also called “Super cooled liquids” because the orientations of molecules are random and highly disordered in the frozen solid state...”P390218USP 3252US01

[0157] Examples of suitable ceramics may include silica, alumina, titania, ceria, zirconia, yttria-stabilized zirconia, other oxides, and other classes of ceramics including carbides, nitrides, sulfides, borides, phosphides, selenides, titanates, carbonates, nitrates, sulfates, borates, and phosphates, or combinations thereof.

[0158] Utilizing particles with a core / shell architecture may confer specific advantages to the membrane-reinforced opaloid. For example, a particle comprising a core that is made of a material with highly tunable shape and particle size distribution may confer the ability to tune the average size and / or to make relatively monodisperse particles. It may also confer superior control over particle shape (e.g., highly spherical or rod-like). The core may also be lighter (i.e., less dense) than other materials. However, the core material may lack sufficient chemical stability for the intended application. Further, a particle comprising a shell of another material may confer favorable properties such as enhanced thermal conductivity, ionic conductance, catalytic activity, or optical properties. Thus, using core / shell particles can be a way to balance engineering trade-offs, such as combining favorable morphology (e.g., size, monodispersity, morphology) with favorable properties (e.g., chemical stability or catalytic activity). Nonlimiting examples of core / shell particles include those with a core of silica and a shell of alumina and / or boehmite.

[0159] The sub-micron particles may be coated in a material, for example to aid in colloidal stabilization of the colloidal suspension or colloidal dispersion, and / or to aid in the formation of the opaloid within the scaffold pores. The material may comprise, for example, a polymeric material (e.g., a dispersing agent).

[0160] The sub-micron particles may be colloidal sub-micron particles. The sub-micron particles may be imbibed within the scaffold pore volume comprising the scaffold pores. The sub-micron particles may be suspended in a liquid as a colloidal precursor (e.g., a colloidal suspension or colloidal dispersion) at least during the imbibing process, where the colloidal precursor may comprise a fluid continuous phase and the sub-micron particles dispersed or suspended within the continuous phase. The composite membrane may comprise an opaloid within the scaffold pores that is fully dried, i.e., the fluid continuous phase between the submicron particles of the opaloid having been substantially removed. The three-dimensional arrangements of sub -micron particles described by the term opaloids within the scaffold pores, as used herein, are not particularly restricted in their method of manufacture, and if the same or similar arrangement of sub-micron particles is made without the use of a precursor that is a colloidal dispersion or colloidal suspension, it may nevertheless be considered an opaloid as defined herein.P390218USP 3252US01Description of Microporous Polymer Scaffolds

[0161] The following description of the microporous polymer scaffolds is applicable to all embodiments, examples and aspects of the composite membranes, systems for use as electrochemical separators, electrochemical devices, supported liquid membranes and methods described herein. As used herein, the term “microporous polymer scaffold” refers to a thin, flexible, freestanding, porous polymer structure that may be configured in a variety of forms such as a porous web (i.e., a long, thin, flexible material typically supplied in roll form), a porous sheet (e.g., a flat sheet), or a porous tube (e.g., a round tube). The microporous polymer scaffold may be in the form of a porous web or porous flat sheet. As used herein, the term “porous” is meant to denote a structure comprising voids (i.e., pores) within a solid matrix. The pores each have a pore volume, and the plurality of pores define the total pore volume of the microporous polymer scaffold (i.e., the scaffold pore volume). The solid matrix (i.e., the scaffold matrix) refers to the solid portion of the microporous polymer scaffold, excluding its pore volume.

[0162] The microporous polymer scaffold may have a first major exterior surface (i.e., a first surface) and a second major exterior surface (i.e., a second surface) that opposes the first surface (in the case of a tube these two surfaces correspond to the inner and outer diameters of the tube). The microporous polymer scaffold may have a thickness, which is the distance between the first and second major exterior surfaces. The plurality of pores have inner surfaces defined by their interfaces with the scaffold matrix. The inner surface of a pore refers to the surface of the pore that is not on an exterior surface of the scaffold.

[0163] As used herein, the term “microporous” refers to a structure, such as a polymer scaffold or membrane, that comprises pores that are not visible to the naked eye and that create passageways extending from the first major surface to the second major surface (i.e., from one exterior surface of the layer to the opposite exterior surface of the layer). Such passageways may be described as “through pores.” The scaffold pore volume may also comprise pores that are not “through pores” (i.e., some pores may not be connected to both exterior surfaces through the scaffold pore volume). Such pores that are connected to only one exterior surface may be described as “dead-end pores,” and such pores that are not connected to either exterior surface may be described as “closed-cell pores.” Within the scaffold pore volume, all of the pores may be interconnected and may form a continuous porous network, or all of the pores may be isolated from each other, or there may be any intermediate level of interconnection among the pores. In some embodiments, the term “microporous” may have a maximum pore size as defined by its bubble point that is less than about 1000 pm. The scaffold pores may have an average pore size on a volume basis (e.g., as measured by BET / BJH) from about 0.01 to about 100 pm, e.g., from about 0.01 to about 1 pm, or about 0.02 to about 25 pm, or about 0.01 to about 10 pm, or about 0.05 to about 20P390218USP 3252US01pm, or about 0.1 to about 80 pm, or about 0.1 to about 50 pm, or about 0.1 to about 30pm, or about 0.2 to about 60 pm, or about 0.5 to about 50 pm, or any intermediate range or value between about 0.01 to 100 pm. The scaffold pores may have a median pore size on a volume basis (e.g., as measured by BET / BJH) from about 0.01 to about 100 pm, e.g., from about 0.01 to about 1 pm, or about 0.02 to about 25 pm, or about 0.01 to about 10 pm, or about 0.05 to about 20 pm, or about 0.1 to about 80 pm, or about 0.1 to about 50 pm, or about 0.1 to about 30pm, or about 0.2 to about 60 pm, or about 0.5 to about 50 pm, or any intermediate range or value between about 0.01 to 100 pm. The scaffold pores may have a primary mode pore size (i.e., the pore size corresponding to the peak of the largest mode) on a volume basis (e.g., as measured by BET / BJH) from about 0.01 to about 100 pm, e.g., from about 0.01 to about 1 pm, or about 0.02 to about 25 pm, or about 0.01 to about 10 pm, or about 0.05 to about 20 pm, or about 0.1 to about 80 pm, or about 0.1 to about 50 pm, or about 0.1 to about 30pm, or about 0.2 to about 60 pm, or about 0.5 to about 50 pm, or any intermediate range or value between about 0.01 to 100 pm. The scaffold pores may have a primary mode pore size (i.e., the pore size corresponding to the peak of the largest mode) on a number basis (e.g., as measured by BET / BJH) from about 0.01 to about 100 pm, e.g., from about 0.01 to about 1 pm, or about 0.02 to about 25 pm, or about 0.01 to about 10 pm, or about 0.05 to about 20 pm, or about 0.1 to about 80 pm, or about 0.1 to about 50 pm, or about 0.1 to about 30pm, or about 0.2 to about 60 pm, or about 0.5 to about 50 pm, or any intermediate range or value between about 0.01 to 100 pm. The scaffold pores may have a mean flow pore size (e.g., as measured by Capillary Flow Porometry) from about 0.01 to about 100 pm, e.g., from about 0.01 to about 1 pm, or about 0.02 to about 25 pm, or about 0.01 to about 10 pm, or about 0.05 to about 20 pm, or about 0.1 to about 80 pm, or about 0.1 to about 50 pm, or about 0.1 to about 30pm, or about 0.2 to about 60 pm, or about 0.5 to about 50 pm, or any intermediate range or value between about 0.01 to 100 pm.

[0164] The scaffold matrix may comprise a continuous network of interconnected material elements, and the scaffold pores may be void spaces between these material elements. The material elements may comprise a wide variety of structural components that form the building blocks of the overall scaffold structure. The material elements are not particularly limited, and may comprise, for example, fibers, bundles of fibers, nodes, and fibrils. In one embodiment, the microporous polymer scaffold may have a structure comprising fibers, bundles of fibers, and a plurality of scaffold pores, where the fibers and bundles of fibers are interconnected, and the plurality of scaffold pores are void spaces between the fibers and bundles of fibers. In another embodiment, the microporous polymer scaffold may have a microstructure comprising nodes, fibrils, and a plurality of scaffold pores, where the nodes are interconnected by the fibrils, and the plurality of scaffold pores are void spaces between the nodes and fibrils.P390218USP 3252US01

[0165] A suitable microporous polymer scaffold depends largely on the intended application. The microporous polymer scaffold may support and mechanically reinforce composite materials or membranes (e.g., a composite membrane such as a membrane-reinforced opaloid), improving its structural integrity, handleability, and durability. The microporous polymer scaffold may enable the composite membrane to be thin (e.g., less than about 150 microns) and / or have a large area while retaining handleability and other desirable properties. The microporous polymer scaffold may have good mechanical properties and be thermally, chemically, and electrochemically stable in the environment in which the composite membrane is to be used. The microporous polymer scaffold may also be tolerant of any manufacturing steps required in the production of the composite membrane, as well as in the subsequent storage, shipping, and handling of the composite membrane.

[0166] The microporous polymer scaffold may be stable (e.g., practically insoluble) at very high pH (e.g., above about pH 10, or above about pH 11, or above about pH 12, or above about pH 13, or above about pH 14). Additionally, the microporous polymer scaffold may be stable at very low pH (e.g., below about pH 5, or below about pH 4, or below about pH 3, or below about pH 2, or below about pH 1, or below about pH 0).

[0167] The microporous polymer scaffold may be formed by any suitable method applicable for the intended application. The method of manufacturing the microporous polymer scaffold is not particularly limited, and any conventional method known in the art may be used to form the microporous polymer scaffold. Non-limiting examples of suitable processing methods include roll-to-roll processing, paste processing, gel processing, and expansion. The microporous polymer scaffold may be a microporous polymer membrane or polymer substrate. Depending largely on the method of manufacture, the microporous polymer scaffold may have a machine direction (MD) and a transverse direction (TD), where the MD is orthogonal to the TD, and the MD and TD are each orthogonal to the thickness direction. For webs, MD aligns with the long direction (typically the direction of travel along the process line that fabricated the web), and TD aligns with the width direction.

[0168] The microporous polymer scaffold may be formed from / of any suitable material for the intended application. The material is not particularly limited and may be any material known to those of skill in the art to form the microporous polymer scaffold. In some embodiments, the microporous polymer scaffold may comprise polymeric materials. The polymeric materials may comprise a polymer or a mixture of polymers. The polymeric materials may comprise a homopolymer or a copolymer. The polymeric materials may comprise inorganic polymeric materials and / or organic polymeric materials. The polymeric materials may comprise fluorine and / or heteroatoms. The polymeric materials may comprise aromatic moieties and / or non-aromatic (e.g., aliphatic or olefinic) moieties. The polymeric materials may comprise side chains and / or functional groups. The polymeric materials mayP390218USP 3252US01comprise a polymer that is fibrillatable (e.g., PTFE). As used herein, the term “fibrillatable” refers to the ability of a polymer to form a fibril microstructure, such as, for example, by solid state deformation or paste processing. The microporous polymer scaffold may be formed from a non-fluorinated polymer, a partially fluorinated polymer, a perfluorinated polymer, and any combination thereof. The microporous polymer scaffold may comprise polyolefins such as polyethylene (PE) or polypropylene (PP). The microporous polymer scaffold may comprise a polytetrafluoroethylene (PTFE), a polyethylene (PE), or a copolymer of PTFE and PE. The microporous polymer scaffold may comprise an expanded polytetrafluoroethylene (ePTFE) or an expanded polyethylene (ePE). In embodiments where the polymer is non-fluorinated, the non-fluorinated polymer may be selected from a hydrocarbon polymer.

[0169] One non-limiting method to produce porous polytetrafluoroethylene (PTFE) membranes is through paste processing with subsequent expansion to form expanded polytetrafluoroethylene (ePTFE). ePTFE is referred to herein for ease of discussion, but it is to be appreciated that expanded modified PTFE, expanded blends of PTFE, expanded copolymers of PTFE, and PTFE homopolymers are all considered to be within the purview of the invention. Patents have been issued on expandable blends of PTFE, expandable modified PTFE, and expanded copolymers of PTFE, such as, for example, U. S. Patent No. 5,708,044 to Branca; U. S. Patent No. 6,541,589 to Baillie; U. S. Patent No. 7,531,611 to Sabol et al.; U. S. Patent No. 8,647,144 to Ford; U. S. Patent No. 8,158,235, U. S. Patent No. 7,306,729 and U. S. Patent No. 9,139,669 to Xu et al.

[0170] A non-limiting method to produce porous polyethylene membranes is through a wet or gel process known in the industry. In this process, polyethylene may be mixed with a hydrocarbon liquid and other additives. This mixture may be heated above the polymer melt temperature and extruded into a sheet. This sheet can then be orientated biaxially before and / or after the hydrocarbon liquid is extracted, producing a microporous membrane. Various process details are known in literature as in U. S. Patent No. 5,248,461, U. S. Patent No.4,873,034, U. S. Patent No. 5051183, U. S. Patent No. 6566012, Casting and stretching of filled and unfilled UHMW-polyethylene films, Ir. F. H. Assinck, Centre for polymers and composites, Eindhoven University of Technology, Nov 1995 and Porous biaxially drawn ultra-high molecular weight polyethylene films, N. S. J. A. Gerrits, Department of Materials Technology, DSM Research; and P. J. Lemstra, Department of Polymer Technology, Eindhoven University of Technology, October 1990.

[0171] The microporous polymer scaffold may have a mass per area of about 0.5 g / m2to about 50 g / m2, or about 0.5 g / m2to about 40 g / m2, or about 0.5 to about 30 g / m2, or about 0.5 g / m2to about 20 g / m2, or about 0.5 g / m2to about 10 g / m2, or about 0.5 g / m2to about 5 g / m2,P390218USP 3252US01or about 5 g / m2to about 50 g / m2, or about 5 g / m2to about 40 g / m2, or about 5 to about 30 g / m2, or about 5 g / m2to about 20 g / m2, or about 5 g / m2to about 10 g / m2.

[0172] The microporous polymer scaffold may have a non-contact thickness of up to about 1000 pm. The microporous polymer scaffold may have a non-contact thickness of from about 1 pm to about 1000 pm, or from about 2 pm to about 1000 pm, or from about 2 pm to about 500 pm. The microporous polymer scaffold may have a non-contact thickness of greater than 2 pm and up to about 1000 pm, greater than 2 pm and up to about 900 pm, greater than 1 pm and up to about 800 pm, greater than 1 pm and up to about 700 pm, greater than 1 pm and up to about 600 pm, greater than 1 pm and up to about 500 pm, greater thanl pm and up to about 400 pm, greater than 1 pm and up to about 300 pm, greater than 1 pm and up to about 200 pm, or greater than 1 pm and up to about 150 pm, or greater than 1 pm and up to about 100 pm, or greater than 1 pm and up to about 75 pm, or greater than 1 pm and up to about 50 pm, or greater than12 pm and up to about 25 pm, or greater than 1 pm and up to about 10 pm, or greater than 1 pm and up to about 5 pm, or up to about2 pm, or up to about 1 pm. In some embodiments, the microporous polymer scaffold may have a non-contact thickness of any value including and between about 2 pm to about 500 pm, or between about 2 pm and about 100 pm, or about 2 pm and about 50 pm, or about 2 pm and about 25 pm.

[0173] The non-contact thickness of the microporous polymer scaffold is measured as indicated in the test methods described herein.

[0174] The microporous polymer scaffold may have a porosity of at least 40 vol%, or at least 50 vol%, or at least 60 vol%, or at least 67 vol%, or at least 70 vol %, or at least 75 vol%, or at least 80 vol%, or at least 82 vol%, or at least 84 vol%, or at least 86 vol%, or at least 88 vol%, or at least 90 vol%, or at least 91 vol%, or at least 95 vol%, or at least 98 vol%, or any intermediate value or range of values in the range from 40 vol% to 98 vol%. In some embodiments, the microporous polymer scaffold may have a porosity from about 40 vol% to about 98 vol%, or from about 40 vol% to about 91 vol%, or from about 40 vol %to about 90 vol%, or from about 40vol% to about 85 vol%, or from about 40 vol% to about 80 vol%, or from about 40 vol% to about 75 vol%, or from about 40 vol% to about 70 vol%, or from about 40 vol% to about 60 vol%, or from about 50 vol% to about 98 vol%, or from about 50 vol% to about 91 vol%, or from about 50 vol %to about 90 vol%, or from about 50 vol% to about 85 vol%, or from about 70 vol % to about 90 vol%, or from about 50 vol% to about 80 vol%, or from about 50 vol% to about 75 vol%, or from about 50 vol% to about 70 vol%, or from about 50 vol% to about 60 vol%. In some embodiments, the microporous polymer scaffold may have a porosity from about 83 vol% to about 91 vol%.P390218USP 3252US01

[0175] The microporous polymer scaffold may have a bubble point pressure equal to or greater than about 0.5 bar, or equal to or greater than about 1 bar or equal to or greater than about 2 bar. The microporous polymer scaffold may have a bubble point pressure of from about 0.5 bar to about 10 bar, or from about 1 bar to about 10 bar, or from about 2 bar to about 15 bar, or from about 2 bar to about 10 bar, or from about 2 bar to about 5 bar, or from about 3 bar to about 9 bar, or from about 3 bar to about 8 bar, or from about 4 bar to about 9 bar, or from about 4 bar to about 8 bar. The microporous polymer scaffold may have a bubble point pressure of equal to or greater than about 4 bar, or equal to or greater than about 5 bar, or equal to or greater than about 6 bar, or equal to or greater than about 7 bar, or equal to or greater than about 8 bar, or equal to or greater than about 9 bar, or equal to or greater than about 10 bar.

[0176] The microporous polymer substrate has a first direction, a second direction, and a thickness direction, where the first direction is orthogonal to the second direction, and the first and second directions are each orthogonal to the thickness direction, where the second direction is the direction in which the microporous polymer substrate has its minimum matrix tensile strength. In some embodiments, the microporous polymer substrate may have a matrix tensile strength (MTS) in the second direction of at least about 50 MPa. The microporous polymer substrate may have a matrix tensile strength in the second direction of at least about 100 MPa, or at least about 300 MPa, or at least about 400 MPa, or at least about 500 MPa. The microporous polymer substrate may have a matrix tensile strength between about 50 MPa to about 500 MPa, or about 150 MPa to about 450 MPa, or about 250 MPa to about 450 MPa, or any intermediate values and ranges between about 50 MPa to about 500 MPa.

[0177] It is not necessary to measure the strength of the microporous polymer scaffold in every possible direction in order to determine the direction having the minimum strength. For microporous polymer scaffolds produced via a roll-to-roll process, it is typical for the minimum matrix tensile strength to align with either the MD or TD direction of the roll. Therefore, unless there is specific knowledge to the contrary, it may be presumed that the direction of minimum strength aligns with whichever direction has the lowest strength selected from TD or MD.

[0178] The microporous polymer scaffold may have a matrix tensile strength (MTS) in the second direction of at least about 60 MPa, or at least about 70 MPa, or at least about 80 MPa, or at least about 90 MPa, or at least about 100 MPa, or at least about 110 MPa, or at least about 120 MPa, or at least about 130 MPa, or at least about 140 MPa, or at least about 150 MPa, or at least about 160 MPa, or at least about 170 MPa, or at least about 180 MPa, or at least about 190 MPa, or at least about 200 MPa, or at least about 210 MPa, or at least about 220 MPa, or at least about 230 MPa, or at least about 240 MPa, or at least about 250 MPa.P390218USP 3252US01

[0179] The microporous polymer scaffold may have a matrix tensile strength (MTS) in the second direction of from about 55 MPa to about 425 MPa, or from about 55 MPa to about 400 MPa, or from about 80 MPa to about 400 MPa, or from about 100 MPa to about 400 MPa, or from about 120 MPa to about 400 MPa, or from about 140 MPa to about 400 MPa, or from about 160 MPa to about 350 MPa. The matrix tensile strength (MTS) of the microporous polymer scaffold is measured as indicated in the test methods described herein.

[0180] The microporous polymer scaffold may have a geometric mean MTS of at least about 90 MPa. The geometric mean MTS is defined as the square root of the product of the MTS in the first direction and the MTS in the second direction:Geometric mean MTS=^(MTS in the first direction xMTS in the second direction)

[0181] The microporous polymer scaffold may have a geometric mean MTS of at least about 100 MPa, or at least about 110 MPa, or at least about 120 MPa, or at least about 130 MPa. The microporous polymer scaffold may have a geometric mean MTS of from about 90 MPa to about 400 MPa, or from about 100 MPa to about 375 MPa, or from about 110 MPa to about 375 MPa.

[0182] The geometric mean absolute tensile strength of the microporous polymer scaffold / composite membrane contact thickness may be at least about 10 MPa. The geometric mean absolute tensile strength of the microporous polymer scaffold / composite membrane contact thickness may be at least about 15 MPa, or at least about 20 MPa, or at least about 25 MPa, or at least about 30 MPa, or at least about 35 MPa, or at least about 40 MPa, or at least about 45 MPa, or at least about 50 MPa. The geometric mean absolute tensile strength of the microporous polymer scaffold / composite membrane contact thickness may be from about 10 MPa to about 200 MPa, or from about 10 MPa to about 175 MPa, or from about 10 MPa to about 160 MPa.

[0183] The absolute tensile strength of the microporous polymer scaffold is measured as indicated in the test methods described herein.

[0184] The absolute tensile strength of the microporous polymer scaffold in the second direction / composite membrane contact thickness may be at least about 8 MPa. The absolute tensile strength of the microporous polymer scaffold in the second direction / composite membrane contact thickness may be at least about 10 MPa, or at least about 15 MPa, or at least about 20 MPa, or at least about 30 MPa, or at least about 40 MPa, or at least about 50 MPa. The absolute tensile strength of the microporous polymer scaffold in the second direction / composite membrane contact thickness may be from about 10 MPa to about 200 MPa, or from about 15 MPa to about 200 MPa, or from about 20 MPa to about 200 MPa, orP390218USP 3252US01from about 30 MPa to about 200 MPa, or from about 40 MPa to about 175 MPa, or from about 50 MPa to about 175 MPa.

[0185] The microporous polymer scaffold may have a tensile strength balance ratio (absolute tensile strength in the second direction / absolute tensile strength in the first direction) of between about 0.45 and about 1, or between about 0.50 and about 1, or between about 0.55 and about 1, or between about 0.60 and about 1, or between about 0.65 and about 1, or between about 0.70 and about 1, or between about 0.75 and about 1, or between about 0.80 and about 1, or between about 0.85 and about 1, or between about 0.90 and about 1. As discussed above, a value closer to 1 may be preferred because this means that the tensile strength is balanced, and therefore the tensile strengths in the first and second directions are more similar.

[0186] Without wishing to be bound by theory, it is believed that one of the primary functions of the microporous polymer scaffold is to prevent the development of cracks that may be caused by stresses that develop during the drying process of the colloidal dispersion or colloidal suspension as the opaloid is being formed within the scaffold pores. This process of crack formation will be discussed in greater detail in the next section.Crack Formation During Drying

[0187] Without wishing to be bound by theory, it is believed that one of the primary sources of defects in opaloids is cracks that are caused by stresses during drying, as illustrated in Figure 11. As used herein, the term “crack” may describe a fracture within an opaloid phase, which may form during or after the particles consolidate to form the opaloid. In appearance, a crack may be relatively linear or branching, and the contours of the two sides may appear highly complementary (i.e., may appear to “fit together”) consistent with a fractured solid that has been pulled apart. Figure 11 depicts a schematic of a colloidal dispersion being concentrated to form an opaloid. As the system approaches and exceeds the colloidal glass transition point (where the packing density is equal to or greater than the colloidal glass transition packing density), the sub-micron particles become effectively immobilized, and the continued evaporation of the liquid phase results in the formation of menisci that cause compressive stress to build up on the arrangement of sub-micron particles (e.g., due to capillary forces). Differential compression may result in tension and / or shear forces acting on the arrangement of particles. If the opaloid is in contact with a rigid surface then additional tension and / or shear forces may arise as the rigid surface further restrains the arrangement of sub-micron particles. The aforementioned forces may exceed the cohesive forces holding the particles together, resulting in the formation of large cracks (e.g., as shown in Figure 2).Without wishing to be bound by theory, it is believed that microporous polymer scaffolds withP390218USP 3252US01tighter structures (e.g., those with bubble points greater than 2 bar) are better at mechanically reinforcing the arrangement of sub-micron particles during the drying process, thereby minimizing the formation of large cracks (for example, in the case of opaloids prepared from colloidal precursors). Furthermore, tightly packed arrangements of smaller particles may produce larger drying forces than tightly packed arrangements of larger particles Accordingly, microporous polymer scaffolds having a largest pore size (derived from bubble point pressure) less than about 15 times the particle diameter (D) may minimize the formation of large cracks during the drying process, and therefore may be considered High Integrity Membrane Reinforced Opaloids.Overview of Membrane-Reinforced Opaloid Morphology & Properties

[0188] The following description of membrane-reinforced opaloids are applicable to all embodiments, examples and aspects of the composite membranes, systems for use as electrochemical separators, electrochemical devices, supported liquid membranes and methods described herein. MROs may comprise a microporous polymer scaffold where the scaffold matrix is intimately integrated with the opaloid. Figure 12 shows such an MRO, in which the sub-micron particles 10 (comprising silica sub-micron particles with a diameter of approximately 22 nm) of the opaloid 9 are arranged so as to conform to the shape of the scaffold matrix 15 (having the node and fibril microstructure of ePTFE). The pore volume of such an MRO may be dominated by the inter-particle pore volume 13. The intimacy of the integration may be evaluated by measuring (e.g., via quantitative image analysis) the distances from the inner surface of the polymer scaffold to the centers of the nearest submicron particles (i.e., the integration distances, di, as shown in the image). In Figure 12, these distances are generally very small (e.g., less than about 1 particle diameter, D), demonstrating intimate integration with the microporous polymer scaffold as defined herein. Figure 13 shows another such MRO, in which the sub-micron particles 9 comprise a blend of two populations of substantially monodisperse sub-micron particles (silica sub-micron particles 27 having a diameter of approximately 7 nanometers and perfluoroalkoxy alkane sub-micron particles 28 having a diameter of approximately 90 nanometers) in an ePTFE microporous polymer scaffold 15, where the ePTFE had a bubble point of about 1.9 bar.

[0189] In some embodiments, MROs may have large defects (e.g., cracks). Figure 14 shows a surface scanning electron micrograph of an MRO comprising silica sub-micron particles with a diameter of approximately 12 nm and an ePTFE microporous polymer scaffold where the ePTFE had a bubble point of about 1.9 bar. Large defects (e.g., cracks) 26 may be observed in the sample. Defects may be considered large when their widest width is from about 45 nm and about 55 nm, or from about 45 nm and about 60 nm, or from about 45 nmP390218USP 3252US01and about 70 nm, or from about 45 nm and about 75 nm, or from about 45 nm and about 100 nm, or from about 45 nm and about 200 nm, or from about 45 nm and about 250 nm, or from about 45 nm and about 300 nm, or from about 45 nm and about 500 nm, or from about 45 nm and about 750 nm, or from about 45 nm and about 1 micron. Additionally, defects may be considered large when their widest width is from about 50 nm and about 60 nm, or from about 50 nm and about 70 nm, or from about 50 nm and about 75 nm, or from about 50 nm and about 100 nm, or from about 50 nm and about 200 nm, or from about 50 nm and about 250 nm, or from about 50 nm and about 300 nm, or from about 50 nm and about 500 nm, or from about 50 nm and about 750 nm, or from about 50 nm and about 1 micron. Defects may be considered large when their widest width is from about 60 nm and about 70 nm, or from about 60 nm and about 75 nm, or from about 60 nm and about 100 nm, or from about 60 nm and about 200 nm, or from about 60 nm and about 250 nm, or from about 60 nm and about 300 nm, or from about 60 nm and about 500 nm, or from about 60 nm and about 750 nm, or from about 60 nm and about 1 micron. Defects may also be considered large when their widest width is from about 70 nm and about 75 nm, or from about 70 nm and about 100 nm, or from about 70 nm and about 200 nm, or from about 70 nm and about 250 nm, or from about 70 nm and about 300 nm, or from about 70 nm and about 500 nm, or from about 70 nm and about 750 nm, or from about 70 nm and about 1 micron. Defects may be considered large when their widest width is from about 75 nm and about 100 nm, or from about 75 nm and about 200 nm, or from about 75 nm and about 250 nm, or from about 75 nm and about 300 nm, or from about 75 nm and about 500 nm, or from about 75 nm and about 750 nm, or from about 75 nm and about 1 micron. Further, defects may be considered large when their widest width is from about 100 nm and about 200 nm, or from about 100 nm and about 250 nm, or from about 100 nm and about 300 nm, or from about 100 nm and about 500 nm, or from about 100 nm and about 750 nm, or from about 100 nm and about 1 micron. Defects may be considered large when their widest width is from about 200 nm and about 250 nm, or from about 200 nm and about 300 nm, or from about 200 nm and about 500 nm, or from about 200 nm and about 750 nm, or from about 200 nm and about 1 micron. Defects may be considered large when their widest width is from about 250 nm and about 300 nm, or from about 250 nm and about 500 nm, or from about 250 nm and about 750 nm, or from about 250 nm and about 1 micron. Defects may be considered large when their widest width (W) is from about 4.5 particle diameters and about 6 particle diameters (i.e., when 4.5*D < W < 6*D), or when 4.5*D < W < 10*D, or when 4.5*D < W< 20*D, or when 4.5*D < W < 50*D, or when 4.5*D < W < 100*D, or when 4.5*D < W < 200*D, or when 4.5*D < W < 500*D. Defects may be considered large when 5*D < W< 10*D, or when 5*D < W< 20*D, or when 5*D < W< 50*D, or when 5*D < W < 100*D, or when 5*D < W < 200*D, or when 5*D < W < 500*D. Defects may be considered large when 10*D < W< 20*D, or when 10*D < W< 50*D, or when 10*D < W< 100*D, or whenP390218USP 3252US0110*D < W< 200*D, or when 10*D < W< 500*D. Defects may be considered large when 20*D < W < 50*D, or when 20*D < W < 100*D, or when 20*D < W < 200*D, or when 20*D < W < 500*D. Defects may be considered large when 50*D < W < 100*D, or when 50*D < W < 200*D, or when 50*D < W< 500*D, or when 100*D < W< 200*D, or when 100*D < W< 500*D, or 200*D < W < 500*D. When large defects extend through the entirety of the thickness or substantially through the thickness of the MRO, they may compromise the integrity of the MRO as described below, and as indicated by metrics such as a dramatic reduction of the bubble point of the MRO (e.g., to values below about 10 bar). It has been surprisingly discovered that such defects can be minimized or eliminated by fabricating MROs that comprise a microporous polymer scaffold with a bubble point greater than 2 bar. Therefore, as described above, MROs that comprise a microporous polymer scaffold that had a bubble point greater than 2 bar may be considered High-Integrity Membrane-Reinforced Opaloids. Similarly, MROs with bubble points greater than about 10 bar may be considered High-Integrity Membrane-Reinforced Opaloids.

[0190] MROs may comprise an opaloid in which the packing arrangement of the submicron particles is similar to the packing arrangement of a neat (i.e., unreinforced) opaloid formed from the same colloidal dispersion or colloidal suspension without the microporous polymer scaffold. Figure 15 shows SAXS data for two opaloids, one neat and the other an MRO reinforced with an ePTFE microporous polymer scaffold with a bubble point of 7.6 bar, both prepared from an aqueous colloidal dispersion of silica sub-micron particles with a diameter of approximately 12 nm. As indicated by the two leftmost triangles, two major SAXS peaks are observed at virtually identical q values in each case, indicating that the packing arrangement of particles in the MRO (as described by the ID values and the presence of longer-range order) is comparable to that of the neat opaloid.

[0191] MROs may also comprise an opaloid in which the pore phase is similar to the pore phase of the neat opaloid formed from the same colloidal dispersion or colloidal suspension without the microporous polymer scaffold. Figure 16 shows BET / BJH data for four opaloids: neat (i.e., unreinforced), and MROs reinforced with ePTFE microporous polymer scaffolds that had bubble points of 1.9 bar, 4.8 bar, and 7.6 bar. All the pore size distributions have mode pore diameters between about 5 nm and 7 nm, and all overlap to a significant degree. Compared to the neat system (i.e., unreinforced, with no microporous polymer scaffold and therefore no bubble point of the microporous polymer scaffold), as the bubble point of the microporous polymer scaffold increased from 1.9 bar to 4.8 bar to 7.6 bar, the pore volume of the composite membrane shifted to the right (i.e., the pore volume at pore diameters above about 7 nm increased). This is consistent with the hypothesis that microporous polymer scaffolds with tighter structures can disrupt the long-range order of the opaloid more significantly than scaffolds with less tight structures, while maintaining the local three-P390218USP 3252US01dimensional packing arrangement of sub-micron particles. To better quantify this trend, the parameter 4> was defined as shown in Figure 17a, which compares two of the data sets from Figure 16: the data set for the neat (i.e., unreinforced) sample, and the data set for the MRO reinforced with an ePTFE microporous polymer scaffold that had a bubble point of 1.9 bar. As shown in the insets in Figure 17a, <}> was defined as the fraction of the pore volume of the composite membrane (P, expressed in mL / g) that is contained in pores that are larger than the largest pore observed in the corresponding neat opaloid. This definition was developed for MROs in which the microporous polymer scaffold was substantially filled by the opaloid. For MROs with a significant fraction of pores that are not filled by the opaloid, a suitable background subtraction would be required as will be understood by one of ordinary skill in the art. Figure 17b shows how the value of <|> increased with the bubble point of the microporous polymer scaffold when 3 MROs were fabricated, each of which comprised particles with a nominal diameter of 12 nm but comprising ePTFE microporous polymer scaffolds with different bubble points selected from 1.9 bar, 4.8 bar, and 7.6 bar. Without wishing to be bound by theory, the results depicted in Figure 17b are consistent with the hypothesis that microporous polymer scaffolds with tighter structures may disrupt the opaloid more significantly than scaffolds with less tight structures. Figure 17c shows how the value of <|> also increased with particle diameter when 3 MROs were fabricated, each of which comprised an ePTFE microporous polymer scaffold with a bubble point of 1.9 bar but comprising particles of different nominal diameters selected from 7nm, 12nm, and 22 nm. The results shown in Figure 17c demonstrates that opaloids may be disrupted more significantly when the ratio of the particle size (D) to the pore size of the microporous polymer scaffold increases (i.e., when fewer particles can fit within a typical pore of the microporous polymer scaffold). Without wishing to be bound by theory, in both cases (i.e., pertaining to both Figure 17b and Figure 17c), it is believed that the increase in <[> (i.e., the increase in large pores) may be caused by a larger fraction of interfacial particle-scaffold pores compared to inter- particle pores.

[0192] MROs (such as, but not limited to, High-Integrity MROs) may have few or no gross defects (e.g., cracks) that extend through the thickness of the MRO. Figure 18 shows such an MRO 20, in which several defects 26 are observed. It is to be noted that in Figure 16 the defects appear localized, and there is no evidence of gross cracks spanning the entire thickness of the MRO. The magnification of the image is low to enable virtually the full thickness of the membrane to be viewed, although at this magnification the individual submicron particles (comprising silica with a diameter of approximately 7 nm) cannot be readily resolved, and neither can the microporous polymer matrix (comprising ePTFE) due to limited contrast with the opaloid. The homogeneity of the image is further evidence of intimate integration between the opaloid and the microporous polymer scaffold, and also evidence ofP390218USP 3252US01a continuous opaloid phase throughout the MRO, indicating that the extent of the continuous opaloid phase is the same as the length and width of the prepared sample, which was over 15 cm in this case.

[0193] Figures 19, 20, and 21 show that High-Integrity MROs can be made with materials other than just SiC>2 nanoparticles and ePTFE microporous polymer scaffolds. Figures 19a and 19b show a surface SEM and a cross-section SEM, respectively, of a High-Integrity MRO comprising yttria-stabilized zirconia sub-micron particles (particle size 32 nm) in an ePTFE microporous polymer scaffold that had a bubble point (of the scaffold itself) of about 4.8 bar.Figure 20 shows a surface SEM of a High-Integrity MRO comprising yttria-stabilized zirconia sub-micron particles (particle size 32 nm) in a polyethylene microporous polymer scaffold that had a bubble point pressure (of the scaffold itself) of about 3.1 bar. Figure 21 shows a surface SEM of a High-Integrity MRO comprising yttria-stabilized zirconia (YSZ, particle size 32nm) in an ePTFE microporous polymer scaffold where the ePTFE had a bubble point of about 3.3 bar. Figures 22a and 22b show SAXS data collected for the High-Integrity MRO in Figure 21. As discussed previously, the scattering vector or peak position, q (in units of nm1), is proportional to the sine of the scattering angle, 6, and inversely proportional to the wavelength, A, according to the expression: q = 4iTsin(0) / A. Values of q can be converted to real space correlation distances with the relationship d = 2n7q. The triangle indicates a peak position at 19.2 nm, corresponding to an inter-particle distance. The presence of this structure factor peak, and its length scale, which is comparable to the particle size, are characteristic of an opaloid.

[0194] MROs may be produced with large areas, for example 10s of centimeters or more in extent in each of two orthogonal directions. Figure 23a shows a sample of an MRO sitting on a black lab bench. The MRO comprises an ePTFE microporous polymer scaffold that had a bubble point of about 7.6 bar, and silica sub-micron particles with a diameter of about 7 nm. The width of the sample was about 68 millimeters and the length of the sample was about 100 millimeters. The size of the samples appeared to be limited only by the size of practical industrial batch and roll-to-roll processes (which can reach e.g., greater than 1 meter in width and e.g., thousands of meters in length). Figure 23b shows a sample of the same material bent 180° back on itself to illustrate the flexibility of the material. Figure 23c shows a sample of the same material lying flat on a business card with the words beneath the sample clearly legible with minimal distortion, illustrating that the sample was substantially optically clear, which is evidence of intimate integration between the opaloid and the microporous polymer scaffold, as well as high integrity as will be described below.

[0195] MROs may be produced with high integrity as indicated by a high degree of optical clarity, for example if the refractive indices of the microporous polymer matrix and the opaloid are closely matched and if large defects have been minimized. These conditions may beP390218USP 3252US01satisfied in the case of an MRO comprising ePTFE microporous reinforcement and further comprising an opaloid made up of silica sub-micron particles. Figure 23c shows such an MRO, which is substantially clear. Figure 24 shows optical haze measurements of three MROs, each comprising silica sub-micron particles with a diameter of approximately 12 nm, and each comprising a different ePTFE microporous polymer scaffold with one of three different bubble points: 1.9, 4.8, and 7.6 bar. As the scaffold bubble point increased, the haze decreased significantly. Without wishing to be bound by theory, the haze is attributed primarily to the presence of defects large enough to scatter visible light. Therefore, lower haze in these composite membranes is evidence of higher integrity (i.e., fewer and / or smaller defects). MROs may be considered to have high integrity when the haze value is between a lower value of 0% and an upper value of about 65%, or an upper value of about 55%, or an upper value of about 50%, or an upper value of about 45%, or an upper value of about 40%, or an upper value of about 35%, or an upper value of about 30%, or an upper value of about 25%, or an upper value of about 20%, or an upper value of about 15%, or an upper value of about 10%, or an upper value of about 5%. The composite membranes of the present disclosure may have a haze value of from about 5 % to about 65 %.

[0196] MROs may also be produced with high integrity as indicated by a high composite membrane bubble point. MROs with very small pore diameters, for example as shown in Figure 16, should have extremely high bubble points (e.g., greater than about 20 bar according to the Young-Laplace equation as illustrated in Figure 32). However, if there are large defects through the thickness of the MRO (e.g., cracks), then a much lower bubble point may be detected. Figure 25 shows capillary flow porometry measurements of three MROs, each comprising silica sub-micron particles with a diameter of approximately 12 nm, and each comprising a different ePTFE microporous polymer scaffold with one of three different bubble points: 1.9, 4.8, and 7.6 bar. The MRO comprising the microporous polymer scaffold with a bubble point of 1.9 bar has a bubble point pressure of only approximately 9 bar, indicating the presence of a significant population of large defects through the thickness of the membrane. However, the MROs comprising the microporous polymer scaffolds with bubble points of 4.8 and 7.6 bar have bubble points of about 24 bar and > 28 bar, respectively, indicating that large defects (e.g. cracks) have been minimized or eliminated.

[0197] MROs with high integrity (i.e., comprising microporous polymer scaffolds with bubble point greater than 2 bar) may enable dramatic improvements in the ability to selectively separate small molecules from a solvent (e.g., through organic solvent nanofiltration). Figure 26 shows a schematic of an experimental apparatus for performing Organic Solvent Nanofiltration (OSN). A challenge solution produced by dissolving a probe molecule (e.g., rose bengal) in pure ethanol was passed through the MRO samples under a pressure gradient, and the rejection of the rose bengal by the MRO was determined based on the relativeP390218USP 3252US01concentrations of rose bengal in the permeate and retentate. In these OSN tests, the MRO was used as the filter medium (i.e., the layer within the system that selectively separated the target molecule from the solvent, also referred to as “rejecting” the target molecule). Figure 27 shows the results of such Organic Solvent Nanofiltration measurements on three MROs, each comprising silica sub-micron particles with a diameter of approximately 12 nm, and each comprising a different ePTFE microporous polymer scaffold with one of three different bubble points: 1.9, 4.8, and 7.6 bar. The MRO comprising the microporous polymer scaffold with a bubble point of 1.9 bar had a relatively low rejection of about 2.4%. However, the MROs comprising the microporous polymer scaffolds with bubble points of 4.8 and 7.6 bar showed rose bengal rejections of 89% and 95%, respectively, indicating that large defects (e.g. cracks) have been minimized or eliminated.

[0198] To briefly recap, the results shown in Figures 24, 25, and 26 illustrate the dramatic improvement in the integrity of MRO samples when the bubble point of the microporous polymer scaffold was greater than 2 bar. The resulting MROs showed significantly lower haze ( Figure 24), dramatically higher bubble points (Figure25), and a step change in the ability to filter small molecules ( Figure 26).

[0199] MROs are porous, and therefore the liquid permeance (measured in liters / (m-2*hour*bar) or LMH / bar) through MROs under a fixed pressure gradient may be expected to be inversely proportional to the viscosity of the permeating liquid. The same experimental apparatus shown in Figure 26 was used to measure the liquid permeance of 5 liquids through a high-integrity MRO with a thickness of approximately 2.5 microns comprising silica submicron particles with a diameter of approximately 7 nm and an ePTFE membrane with a bubble point of 7.6 bar. The permeance was measured at a constant trans-membrane pressure of 4 bar. The 5 fluids were methanol (viscosity -0.54 cP), ethanol (viscosity -1.07 cP), isopropanol (viscosity -2.04 cP), isobutanol (viscosity -3.95 cP), and 2-ethyl-1 -hexanol (viscosity -6.27 cP), where the symbol is used to mean “approximately.” Figure 28 compares the measured liquid permeance data (round circles) to the expected trend (solid squares). The expected trend is normalized to the permeance of the ethanol measurement (at -1.07 cP) and calculated assuming that permeance is inversely proportional to viscosity. The measured data agree very well with the expected trend, providing strong evidence that the primary mechanism of liquid permeance is viscous flow through porous media, as expected.

[0200] MROs with high integrity may be mechanically robust, for example with respect to liquid permeance under extremely high pressures. Figure 29a shows a high-pressure flow cell that was used to measure liquid permeance at trans-membrane pressures up to 50 bar. Ethanol was passed through a High-Integrity MRO sample under trans-membrane pressures of 10 bar, 20 bar, 40 bar, 50 bar, 40 bar, 20 bar, and 10 bar (in that order) for about 10 minutesP390218USP 3252US01at each setpoint. The MRO had a thickness of about 5 microns and comprised silica submicron particles with a diameter of about 7 nm and an ePTFE microporous polymer scaffold with a bubble point of approximately 7.6 bar. Figure 29b shows the resulting liquid flux (in L*m-2*h-1), and permeance (in LMH / bar) through the MRO. The flux data clearly show the step changes associated with changes in trans-membrane pressure, and show virtually no hysteresis in flux after exposure to trans-membrane pressures up to 50 bar. Similarly, the permeance data show relatively constant permeance throughout the experiment when the flux is normalized for the trans-membrane pressure. This level of mechanical robustness is surprising given how thin the sample was (only about 5 microns) and that the neat (i.e., unreinforced) version of these opaloids are brittle materials, as illustrated in Figure 2. This data provides more evidence of the highly advantageous properties, such as high mechanical robustness, of High-Integrity MROs. Other measurements of permeance or mass transfer may also be used to characterize MROs, such as Gurley measurements and / or other standard air flow measurements.Detailed Description of Membrane-Reinforced Opaloid Morphology

[0201] The following description of membrane-reinforced opaloid morphology is applicable to all embodiments, examples and aspects of the composite membranes, systems for use as electrochemical separators, electrochemical devices, supported liquid membranes and methods described herein. Each scaffold pore having a pore volume may define the volume of an individual pore within the microporous polymer scaffold. The microporous polymer scaffold also has a scaffold pore volume, where the scaffold pore volume is a characteristic of the microporous polymer scaffold (as a whole) and comprises the total pore volume of the microporous polymer scaffold (i.e., comprises the cumulative pore volume of all scaffold pores). The scaffold pore volume is not necessarily constant; for example, it may change as a result of the process to produce the MRO. For example, the scaffold may deform as a result of stresses during coating and / or drying, resulting in either an increase or decrease in its pore volume. For instance, the thickness of the scaffold may decrease (i.e., “collapse”) in response to capillary forces during wetting and / or drying.

[0202] In an MRO as discussed herein, an opaloid is at least partially contained within the plurality of scaffold pores of the microporous polymer scaffold. The opaloid within the plurality of scaffold pores may have undergone a colloidal glass transition. In some embodiments, a neat opaloid is formed from the same or similar sub-micron particles as the MRO. The opaloid within at least one of the plurality of scaffold pores may have a packing arrangement of submicron particles similar to the packing arrangement of a neat opaloid. In this context, the term “similar” is taken to mean comprising structural, material, or performance characteristics thatP390218USP 3252US01are generally the same as, or within the same range (as understood by one of ordinary skill in the art), when compared to an opaloid formed from the same sub-micron particles. As defined herein, a three-dimensional arrangement of sub-micron particles is one that may comprise at least 4 constituent particles, and may comprise at least one particle that is not aligned substantially in-plane with its three nearest-neighbor particles.

[0203] The opaloid within the plurality of scaffold pores may comprise a three-dimensional packing arrangement of the sub-micron particles with an inter-particle distance (ID), or distribution of inter- particle distances. The pores of the composite membrane may be defined at least in part by this inter- particle distance. As used herein, the inter-particle distance may be the distance between the centers of adjacent sub-micron particles (or if the sub-micron particles are non-spherical, then between the centroids of adjacent sub-micron particles). The inter-particle distance may be expressed in e.g., mm, pm, or nm and may be measured as per the test methods described herein. The inter-particle distance (ID) may be, for example, less than about 2 times the particle diameter or effective particle diameter D. The ID may be, for example, less than about 1.1 times the particle diameter or effective particle diameter D (i.e., less than about 1,1*D). The ID may be less than about 1,2*D. The ID may be less than about 1.3*D. The ID may be less than about 1.4*D. The ID may be less than about 1,5*D. The ID may be less than about 1.6*D. The ID may be less than about 1.8*D. The ID may be less than about 2.2*D. The ID may be less than about 2.4*D. The ID may be less than about 2.6*D. The ID may be less than about 2.8*D. The ID may be less than about 3*D. The ID may be between about 0.6*D to about 3*D, or between about 0.7 *D to about 3*D, or between about 0.8*D to about 2*D, or between about 0.9*D to about 1.5*D, or between about 1*D to about 1.3*D. The ID may be, for example, greater than about 0.5 times the effective particle diameter D and less than about 1.75 times the effective particle diameter D. The ID may be, for example, greater than about 0.5 times the effective particle diameter D and less than about 1.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.55 times the effective particle diameter D and less than about 3 times the effective particle diameter D. The ID may be, for example, greater than about 0.55 times the effective particle diameter D and less than about 2.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.55 times the effective particle diameter D and less than about 2 times the effective particle diameter D. The ID may be, for example, greater than about 0.55 times the effective particle diameter D and less than about 1.75 times the effective particle diameter D. The ID may be, for example, greater than about 0.55 times the effective particle diameter D and less than about 1.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.6 times the effective particle diameter D and less than about 3 times the effective particle diameter D. The ID may be, for example, greater than about 0.6P390218USP 3252US01times the effective particle diameter D and less than about 2.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.6 times the effective particle diameter D and less than about 2 times the effective particle diameter D. The ID may be, for example, greater than about 0.6 times the effective particle diameter D and less than about 1.75 times the effective particle diameter D. The ID may be, for example, greater than about 0.6 times the effective particle diameter D and less than about 1.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.65 times the effective particle diameter D and less than about 3 times the effective particle diameter D. The ID may be, for example, greater than about 0.65 times the effective particle diameter D and less than about 2.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.65 times the effective particle diameter D and less than about 2 times the effective particle diameter D. The ID may be, for example, greater than about 0.65 times the effective particle diameter D and less than about 1.75 times the effective particle diameter D. The ID may be, for example, greater than about 0.65 times the effective particle diameter D and less than about 1.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.7 times the effective particle diameter D and less than about 3 times the effective particle diameter D. The ID may be, for example, greater than about 0.7 times the effective particle diameter D and less than about 2.5 times the effective particle diameter D. The ID may be, for example, greater than about 0.7 times the effective particle diameter D and less than about 2 times the effective particle diameter D. The ID may be, for example, greater than about 0.7 times the effective particle diameter D and less than about 1.75 times the effective particle diameter D. The ID may be, for example, greater than about 0.7 times the effective particle diameter D and less than about 1.5 times the effective particle diameter D.

[0204] The composite membranes of the present disclosure may comprise a microporous polymer scaffold that may be intimately integrated with the opaloid (and as defined herein, the opaloid may therefore be intimately integrated with the microporous polymer scaffold). Within a microporous polymer scaffold pore containing the opaloid, the sub-micron particles of the opaloid may be arranged so as to conform to the surface(s) of the microporous polymer scaffold defining the polymer scaffold pore, resulting in an interface between the opaloid and the surface(s) of the microporous polymer scaffold defining the polymer scaffold pore. The opaloid may comprise sub-micron particles at the interface between the opaloid and the inner surfaces of the microporous polymer scaffold pore. Each of these sub-micron particles may be characterized by an integration distance, d,, where d,may be the magnitude (i.e., the length, expressed in nm) of the shortest of the normal vectors extending from the inner surfaces of the microporous polymer scaffold pore to the surface of the sub-micron particle. The opaloid may be considered to be intimately integrated with the microporous polymer scaffold if theP390218USP 3252US01median integration distance d, is less than about 1 sub-micron particle diameter or effective diameter D, or less than about 0.5*D, or less than about 2*D, or less than about 3*D. The median integration distance may be in the range from about 0.5*D to about 3*D, or from about 0.75*D to about 2.5*D, or from about 1*D to about 3*D, or from about 1*D to about 2*D. For an opaloid that is intimately integrated with the microporous polymer scaffold, the median integration distance may be within the same order of magnitude as the sub-micron particle diameter D. The integration distance may be measured using scanning electron microscopy combined with quantitative image analysis as described herein.

[0205] The opaloid within the plurality of scaffold pores may be contained within the scaffold pores. Composite membranes of the present disclosure may be such that at least a portion of the scaffold pores are at least partially filled with sub-micron particles. For example, a plurality of scaffold pores may be at least partially filled with sub-micron particles. As used herein, at least partially filled is meant to encompass composite membranes (e.g., MROs) where a percentage of the scaffold pores are filled with sub-micron particles, for example from about 1% to about 100%, or from 1% to about 90%, or from about 1% to about 80%, or from about 1% to about 75%, or from about 1% to about 50%, or from about 1% to about 25%, or from about 5% to about 60%, or from about 5% to about 40%, or from about 10% to about 45%. or from about 1% to about 15%, or from about 1% to about 10%, or from about 1% to about 5%. At least partially filled can also be taken to encompass composite membranes where the plurality of scaffold pores have an opaloid within their pore volume, but the pore volume of an individual scaffold pore is not completely filled with an opaloid. In some embodiments, more than one opaloid may be positioned within the pore volume. The opaloids may be the same or different compositionally. In addition, the opaloids may have the same or different sub-micron particle size, material, or the same or different size in terms of the extent (e.g. distance and / or area) of each opaloid.

[0206] In some embodiments, all of the scaffold pores of the microporous polymer scaffold may be filled or substantially filled with sub-micron particles. However, due to the limited packing density of the particles, even a scaffold pore that is completely filled with particles may still have a finite level of porosity due to inter-particle pores. By analogy, one may think of a barrel that is “filled” with marbles or wiffle balls; the barrel may be filled such that substantially no more marbles or wiffle balls can fit within it, yet the barrel still contains substantial pore volume due to e.g., “inter-particle pores” (for example, between the marbles or between the wiffle balls), and / or due to e.g., “intra-particle pores” (for example, within the wiffle balls).

[0207] The composite membrane comprises a plurality of composite membrane pores that are at least in part defined by the opaloid. The opaloid within the scaffold pore volume mayP390218USP 3252US01comprise a three-dimensional packing arrangement having spaces between the sub-micron particles in the opaloid. The spaces between the sub-micron particles may be defined as interparticle pores. The inter-particle pores may be typically described in units of vol% or cc / g. The inter-particle pores may define an interconnected pore volume. The interconnected pore volume may be a characteristic of the opaloid. The composite membrane pores may be at least in part defined by the interconnected pore volume of the opaloid. The inter- particle pores of the opaloid may be characterized by an inter-particle pore diameter, d. The opaloid may comprise a ratio (d / D) of the inter-particle pore diameter, d, to particle diameter or effective particle diameter, D, of, for example, about d / D < 0.5, or about d / D < 0.8, or about d / D < 1, or about d / D < 1.1, or about d / D < 1.2, or about d / D < 1.5, or about d / D < 1.8, or about d / D < 2. The inter-particle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.20 to about 2.0, or about 0.20 to about 1.80, or about 0.2 to about 1.50, or about 0.20 to about 1.20, or about 0.20 to about 1.10, or about 0.20 to 1.0, or about 0.20 to about 0.90, or about 0.20 to 0.80, or about 0.20 to about 0.70. The inter-particle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.225 to about 2,0 or about 0.225 to about 1.80, or about 0.225 to about 1.50, or about 0.225 to about 1.20, or about 0.225 to about 1.10, or about 0.225 to 1.0, or about 0.225 to about 0.90, or about 0.225 to 0.80, or about 0.225 to about 0.70. The inter-particle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.25 to about 2,0 or about 0.25 to about 1.80, or about 0.25 to about 1.50, or about 0.25 to about 1.20, or about 0.25 to about 1.10, or about 0.25 to 1.0, or about 0.25 to about 0.90, or about 0.25 to 0.80, or about 0.25 to about 0.70. The inter-particle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.30 to about 2.0, or about 0.30 to about 1.80, or about 0.30 to about 1.50, or about 0.30 to about 1.20, or about 0.30 to about 1.10, or about 0.30 to 1.0, or about 0.30 to about 0.90, or about 0.30 to 0.80, or about 0.30 to about 0.70. The interparticle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.35 to about 2.0, or about 0.35 to about 1.80, or about 0.35 to about 1.50, or about 0.35 to about 1.20, or about 0.35 to about 1.10, or about 0.35 to 1.0, or about 0.35 to about 0.90, or about 0.35 to 0.80, or about 0.35 to about 0.70. The inter- particle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.40 to about 2.0, or about 0.40 to about 1.80, or about 0.40 to about 1.50, or about 0.40 to about 1.20, or about 0.40 to about 1.10, or about 0.40 to 1.0, or about 0.40 to about 0.90, or about 0.40 to 0.80, or about 0.40 to about 0.70. The inter- particle pore diameter to particle diameter or effective particle diameter ratio (d / D) may be from about 0.50 to about 2.0, or about 0.50 to about 1.80, or about 0.50 to about 1.50, or about 0.50 to about 1.20, or about 0.50 to about 1.1, or about 0.50 to 1.0, or about 0.50 to about 0.90, or about 0.50 to 0.80, or about 0.50 to about 0.70.P390218USP 3252US01The inter-particle pore diameter and particle diameter may be measured or characterized by the methods described herein.

[0208] As used herein, the term “filled” is meant to denote that substantially all (i.e., greater than about 95%) of the pore volume of a scaffold pore is occupied by the opaloid (inclusive of both the solid portion and porosity of the opaloid). The composite membrane may, therefore, comprise composite membrane pores derived from the inter-particle spacing of the sub-micron particles of the opaloid within the scaffold pore volume (i.e., inter-particle pores), plus any intra-particle pore volume, and any interfacial particle-scaffold pores between the sub-micron particles of the opaloid and scaffold pore walls. In some embodiments, where for example, significant defects (e.g., cracks) are present in the opaloid, then the composite membrane pores may additionally be derived from any defects (e.g., cracks), if any, in the opaloid. In some embodiments, where for example, the pore volume of each of the plurality of scaffold pores is only partially filled, then the composite membrane pores may additionally be derived from any unfilled pore volume of the scaffold pores.

[0209] The aforementioned inter- particle pores, intra-particle pore volume, and the interfacial particle-scaffold pores within the scaffold pore volume (collectively, the “opaloid pores”) may define a void volume that is characteristic of the opaloid within the scaffold pore volume (i.e., the opaloid void volume, which may be expressed in, for example, cc / g or cc per square meter). The aforementioned opaloid void volume and the solid volume of the submicron particles of the opaloid (together, the “opaloid”), may define a volume that is characteristic of the opaloid phase within the scaffold pore volume (i.e., the opaloid volume, which may be expressed in, for example, cc / g or cc per square meter). To calculate the opaloid void fraction (or opaloid porosity), the numerator should be the opaloid void volume and the denominator should be the opaloid volume. The opaloid porosity within the scaffold pores having opaloid incorporated therein may be from about 15 vol% to about 70 vol%, or about 15 vol% to about 65 vol%, or about 15 vol% to about 60 vol%, or about 15 vol% to about 55 vol%, or about 15 vol% to about 50 vol%. The opaloid porosity within the scaffold pores having opaloid incorporated therein may be from about 20 vol% to about 70 vol%, or about 20 vol% to about 65 vol%, or about 20 vol% to about 60 vol%, or about 20 vol% to about 55 vol%, or about 20 vol% to about 50 vol%. The opaloid porosity within the scaffold pores having opaloid incorporated therein may be from about 25 vol% to about 70 vol%, or about 25 vol% to about 65 vol%, or about 25 vol% to about 60 vol%, or about 25 vol% to about 55 vol%, or about 25 vol% to about 50 vol%. The opaloid porosity within the scaffold pores having opaloid incorporated therein may be from about 30 vol% to about 50 vol%, or from about 30 vol% to about 55 vol%, or from about 30 vol% to about 60 vol%, or from about 30 vol% to about 65 vol%, or from about 30 % to about 66%, or about 30 vol% to about 70 vol%. The opaloidP390218USP 3252US01porosity within the scaffold pores having opaloid incorporated therein may be from about 35 vol% to about 50 vol%, or from about 35 vol% to about 55 vol%, or from about 35 vol% to about 60 vol%, or from about 35 vol% to about 65 vol%, or from about 35 % to about 66%, or about 35 vol% to about 70 vol%. The opaloid porosity within the scaffold pores having opaloid incorporated therein may be from about 40 vol% to about 50 vol%, or from about 40 vol% to about 55 vol%, or from about 40 vol% to about 60 vol%, or from about 40 vol% to about 65 vol%, or from about 40 % to about 66%, or about 40 vol% to about 70 vol%. The opaloid porosity within the scaffold pores having opaloid incorporated therein may be from about 45 vol% to about 50 vol%, or from about 45 vol% to about 55 vol%, or from about 45 vol% to about 60 vol%, or from about 45 vol% to about 65 vol%, or from about 45 % to about 66%, or about 45 vol% to about 70 vol%. In some embodiments, the opaloid porosity within the scaffold pores having opaloid incorporated therein may be about 50 vol%. The opaloid within the plurality of scaffold pores may comprise sub-micron particles having a packing density. Opaloid packing density may be calculated by taking a ratio where the numerator is the sum of the solid volume of the sub-micron particles and the intra-particle void volume, and the denominator is the opaloid volume. The sub-micron particles within the opaloid may have a packing density within the scaffold pore volume that may be greater than or equal to the packing density of the corresponding neat opaloid, and / or greater than or equal to a colloidal glass transition packing density (or volume fraction) for the sub-micron particles when in a colloidal system.

[0210] The opaloid within the scaffold pore volume may have a packing density of submicron particles of about 0.4, or about 0.45, or about 0.49, or about 0.5, or about 0.55, or about 0.58, or about 0.60, or about 0.65, or about 0.7, or about 0.75, or about 0.8, or about 0.85. The opaloid within the scaffold pore volume may have a packing density of sub-micron particles of from about 0.4 to about 0.85, or from about 0.5 to about 0,85, or from about 0.4 to about 0.8, or from about 0.4 to about 0.75, or from about 0.5 to about 0.8,

[0211] The opaloid within the scaffold pore volume may have a pore size (d) to interparticle distance (ID) ratio (d / ID) from about 0.07 to about 4.0, or from about 0.07 to about 2.5, or from about 0.07 to about 1.75, or from about 0.07 to about 1.0, or from about 0.07 to about 0.75, or from about 0.07 to about 0.5, or from about 0.1 to about 4.0, or from about 0.1 to about 2.5, or from about 0.1 to about 1.75, or from about 0.1 to about 1.0, or from about 0.1 to about 0.75, or from about 0.1 to about 0.5, or from about 0.15 to about 4.0, or from about 0.15 to about 2.5, or from about 0.15 to about 1.75, or from about 0.15 to about 1.0, or from about 0.15 to about 0.75, or from about 0.15 to about 0.5, or from about 0.2 to about 4.0, or from about 0.2 to about 2.5, or from about 0.2 to about 1.75, or from about 0.2 to about 1.0, or from about 0.2 to about 0.75, or from about 0.2 to about 0.5, or from about 0.25 to aboutP390218USP 3252US014.0, or from about 0.25 to about 2.5, or from about 0.25 to about 1.75, or from about 0.25 to about 1.0, or from about 0.25 to about 0.75, or from about 0.25 to about 0.5, or from about 0.3 to about 4.0, or from about 0.3 to about 2.5, or from about 0.3 to about 1.75, or from about 0.3 to about 1.0, or from about 0.3 to about 0.75, or from about 0.3 to about 0.5.

[0212] The composite membrane may have a porosity, where the porosity may be defined by the void spaces formed by the interconnected pore volume (e.g., the inter- particle pores as defined above) of the opaloid, any intra-particle pore volume, any interfacial particle-scaffold pores, any defects (e.g., cracks), if any, in the opaloid, and, in some examples, any unfilled scaffold pores or unfilled scaffold pore volumes. The composite membrane may comprise a porosity of between about 10 vol% to about 45 vol%, or about 10 vol% to about 50 vol%, or about 10 vol% to about 55 vol%, or about 10 vol% to about 60 vol%, or about 10 vol% to about 65 vol%, or about 10 vol% to about 70 vol%, or about 10 vol% to about 75 vol%. The composite membrane may comprise a porosity from about 15 vol% to about 45 vol%, or from about 15 vol% to about 50 vol%, or from about 15 vol% to about 55 vol%, or from about 15 vol% to about 60 vol%, or from about 15 vol% to about 65 vol%, or from about 15 vol% to about 70 vol%, or from about 15 vol% to about 75 vol%. The composite membrane may comprise a porosity from about 20 vol% to about 45 vol%, or from about 20 vol% to about 50 vol%, or from about 20 vol% to about 55 vol%, or from about 20 vol% to about 60 vol%, or from about 20 vol% to about 65 vol%, or from about 20 vol% to about 70 vol%, or from about 20 vol% to about 75 vol%. The composite membrane may comprise a porosity from about 25 vol% to about 45 vol%, or from about 25 vol% to about 50 vol%, or from about 25 vol% to about 55 vol%, or from about 25 vol% to about 60 vol%, or from about 25 vol% to about 65 vol%, or from about 25 vol% to about 70 vol%, or from about 25 vol% to about 75 vol%. The composite membrane may comprise a porosity from about 30 vol% to about 45 vol%, or from about 30 vol% to about 50 vol%, or from about 30 vol% to about 55 vol%, or from about 30 vol% to about 60 vol%, or from about 30 vol% to about 65 vol%, or from about 30 vol% to about 70 vol%, or from about 30 vol% to about 75 vol%. The composite membrane may comprise a porosity from about 35 vol% to about 45 vol%, or from about 35 vol% to about 50 vol%, or from about 35 vol% to about 55 vol%, or from about 35 vol% to about 60 vol%, or from about 35 vol% to about 65 vol%, or from about 35 vol% to about 70 vol%, or from about 35 vol% to about 75 vol%. In some embodiments, the composite membrane porosity may be about 40 vol%.

[0213] The opaloid itself may be considered to have an opaloid pore volume and pore size. The opaloid pores may be described by considering the specific pore volume (cc / g) in a specific pore size range in the pore size distribution characterized by N2 sorption (as described by the test methods disclosed herein). In analyzing the pore size distribution of the compositeP390218USP 3252US01membrane there will be a peak in the specific pore volume, which may be associated with the inter-particle pore size (d) within the opaloid based on the aforementioned criteria for the interparticle pore size. The peak may, in some embodiments, be the mode pore size (nm) with the highest specific pore volume (for example, in cases where the composite membrane pore size is dominated by the inter-particle pores of the three-dimensional packing arrangement of the opaloid). In other embodiments, the peak may instead be one of several peaks, each of which indicates the contribution from, for example, any of any defects (e.g., cracks) in the opaloid, and any unfilled pore volume of the scaffold pore. The opaloid pore size may be characterized by a mode pore size. The opaloid pore size may be within about 0.15 times to about 2 times the sub-micron particle diameter or equivalent diameter, D. The opaloid pore size may be within about 0.15 to about 1.5 times the sub-micron particle diameter or equivalent diameter, D (i.e., about 0.15*D to about 1.5*D). The opaloid pore size may be within about 0.2*D to about 1.0*D, or about 0.25*D to about 0.75*D, or about 0.3*D to about 0.7*D. The opaloid pore size may be about 0.7*D for small sub-micron particles (i.e., D of about 7 nm), and about 0.4*D for intermediate sub-micron particles (i.e., D of about 12 nm to about 45 nm), and about 0.3*D for larger sub-micron particles (i.e., D of about 100 nm). The opaloid pore size may be about 0.15*D, or about 0.2*D, or about 0.3*D, or about 0.4*D, or about 0.5*D, or about 0.6*D, or about 0.7*D, or about 0.8*D, or about 0.9*D, or about 1*D, or about 1,1*D, or about 1,2*D, or about 1.3*D, or about 1.4*D, or about 1.5*D, about 1.75*D, or about 2D, or any range in between. In some embodiments, the opaloid pore size may be about 0.25*D to about 0.75*D.

[0214] The opaloid pores may have a mode pore size of from about 1 nm to about 1 pm, or from about 1 nm to about 50 nm, or from about 1 nm to about 100 nm, or from about 2 nm to about 50 nm. The opaloid pores may have a mode pore size of from about 2 nm to about 20 nm, or about 2 nm to about 25 nm, or about 2 nm to about 30 nm, or about 2 nm to about 40 nm, or about 2 nm to about 60 nm, or about 2 nm to about 80 nm, or about 2 nm to about 100 nm. The opaloid pores may have a mode pore size of from about 5 nm to 20 nm, or from about 5 nm to about 30 nm, or from about 5 nm to about 40 nm, or from about 5 nm to about 50 nm, or from about 5 nm to about 60 nm, or from about 5 nm to about 80 nm, or from about 5 nm to about 100 nm. The opaloid pores may have a mode pore size of from about 10 nm to 20 nm, or about 10 nm to about 30 nm, or about 10 nm to about 40 nm, or about 10 nm to about 50 nm, or about 10 nm to about 60 nm, or about 10 nm to about 80 nm, or about 10 nm to about 100 nm. The opaloid pores may have a mode pore size of from about 20 nm to about 30 nm, or about 20 nm to about 40 nm, or about 20 nm to about 50 nm, or about 20 nm to about 60 nm, 20 nm to about 80 nm, or about 10 nm to about 100 nm. The opaloid pores may have a mode pore size of from about 30 nm to about 40 nm, or about 30 nm to about 50 nm, or about 30 nm to about 60 nm, 30 nm to about 80 nm, or about 30 nm to about 100 nm. TheP390218USP 3252US01opaloid pores may have a mode pore size of from about 40 nm to about 50 nm, or about 40 nm to about 60 nm, 40 nm to about 80 nm, or about 40 nm to about 100 nm. The opaloid pores may have a mode pore size of from about 50 nm to about 70 nm, 50 nm to about 80 nm, or about 50 nm to about 100 nm.

[0215] In analyzing the pore size distribution of the composite membrane, the opaloid pore size may also be compared to the maximum pore size of neat opaloid comprising the same sub-micron particles and the fraction (<b) of composite membrane pores that have an opaloid pore size larger than the maximum neat opaloid pore size and less than 80 nm (as may be determined by the methods described herein), where the maximum neat opaloid pore size is the maximum pore size less than or equal to 80 nm in a neat opaloid comprising the same sub-micron particles. As used herein, 80 nm was the maximum pore size measured using N2 sorption pore size distributions, for all particle sizes investigated. < J> may be less than about 0.7, or less than about 0.6, or less than about 0.5, or less than about 0.4, or less than about 0.3, or less than about 0.2. <t> may depend on the pore size of the microporous polymer scaffold, on the sub-micron particle diameter D, and / or on the ratio of the two.

[0216] The opaloid may comprise a continuous opaloid phase that extends continuously within at least a portion of the scaffold pores in at least one direction at least about 1 mm, or at least about 5 mm, or at least about 10 mm, or at least about 20 mm, or at least about 40 mm, or at least about 50 mm, or at least about 75 mm, or at least about 100 mm, or at least 150 mm, or at least 200 mm, or at least 300 mm or, from about 1 mm to about 300 mm, or from about 1 mm to about 250 mm, from about 1mm to about 200 mm, from about 1 mm to about 150 mm, from about 1 mm to about 100 mm, from about 1 mm to about 75 mm, from about 1 mm to about 50 mm, from about 1 mm to about 40 mm, from about 1 mm to about 30 mm, from about 1 mm to about 20 mm, from about 1 mm to about 10 mm, from about 1 mm to about 5 mm, or any intermediate value from about 1 mm to about 300 mm (i.e., the “extent” of the opaloid). In this context, the term “extends continuously” (i.e. the extent of the opaloid) is not intended to describe the distance along a continuous path of the opaloid within the scaffold pores (which may, for example, comprise a torturous or indirect path within the scaffold pore volume) but rather, the term “extends continuously” is intended to encompass the displacement between two points of the opaloid within the scaffold pores that are connected by such a continuous path within the scaffold pore volume.

[0217] As used herein, the continuous opaloid phase comprises a continuous pore volume defined by the inter-particle spacing of the opaloid. The opaloid may comprise a continuous opaloid phase that extends over an area of the scaffold pores and / or the scaffold pore volume, where the area of the continuous opaloid phase may be at least about 1 mm, or at least about 5 mm, or at least about 10 mm, or at least about 20 mm, or at least about 40 mm, or at leastP390218USP 3252US01about 50 mm, or at least about 75 mm, or at least about 100 mm, or at least 150 mm, or at least 200 mm, or at least 300 mm or from about 1 mm to about 300 mm, or from about 1 mm to about 250 mm, from about 1mm to about 200 mm, from about 1 mm to about 150 mm, from about 1 mm to about 100 mm, from about 1 mm to about 75 mm, from about 1 mm to about 50 mm, from about 1 mm to about 40 mm, from about 1 mm to about 30 mm, from about 1 mm to about 20 mm, from about 1 mm to about 10 mm, from about 1 mm to about 5 mm, or any intermediate value from about 1 mm to about 300 mm, in displacement in two orthogonal directions of the composite membrane. The displacement over which the area extends in each orthogonal direction may be a different value selected from the aforementioned ranges. The extent of the opaloid may be measured, for example, by using representative SEM images to confirm that the opaloid phase is continuous, and then measuring the macroscopic extent of the opaloid phase visually (and confirming with, for example, a tape measure or ruler, or similar measuring device).

[0218] The composite membrane may have a bubble point pressure of from about 1 bar and about 15 bar, or about 1 bar and about 20 bar, or about 1 bar and about 25 bar, about 1 bar and about 27 bar, or about 1 bar and about 30 bar. The composite membrane may have a bubble point pressure of from about 5 bar and about 15 bar, or about 5 bar and about 20 bar, or about 5 bar and about 25 bar, about 5 bar and about 27 bar, or about 5 bar and about 30 bar. The composite membrane may have a bubble point pressure of from about 10 bar and about 15 bar, or about 10 bar and about 20 bar, or about 10 bar and about 25 bar, about 10 bar and about 27 bar, or about 10 bar and about 30 bar. The composite membrane may have a bubble point pressure of from about 15 bar and about 20 bar, or about 15 bar and about 25 bar, about 15 bar and about 27 bar, or about 15 bar and about 30 bar. The composite membrane may have a bubble point pressure of from about 20 bar and about 25 bar, about 20 bar and about 27 bar, or about 20 bar and about 30 bar. The composite membrane may have a bubble point pressure of from about 25 bar and about 27 bar, or about 25 bar and about 30 bar. The bubble point pressure of the composite membrane is measured as indicated in the test methods described herein.

[0219] The bubble point pressure of the composite membrane may be considered to be a measure of a characteristic pore size of the composite membrane (i.e., the largest through-pore), for example, a composite membrane having a high bubble point pressure (for example, having a bubble point pressure that is equal to or greater than 10 bar) may be considered to have relatively few large defects that extend through the thickness. That is to say, if the composite membrane does comprise any defects (e.g., cracks), these are few in number and may be considered to be largely limited to localized defects (i.e., those that do not span theP390218USP 3252US01full thickness of the composite membrane). Accordingly, such composite membranes of the present disclosure may be referred to as high-integrity membrane-reinforced opaloids.

[0220] The composite membranes described herein have a total surface area, where the total surface area comprises contributions from the microporous polymer scaffold and the submicron particles (e.g., the opaloid). The composite membranes of the present disclosure may have a surface area in which the contribution of the sub-micron particles (i.e., the opaloid) within the pore volume of the microporous polymer scaffold comprises from about 10% to about 20%, or about 10% to about 30%, or about 10% to about 40%, or about 10% to about 50%, or about 10% to about 60%, or about 10% to about 70%, or about 10% to about 80%, or about 10% to about 90% of the surface area based on the total surface area of the composite membrane. The composite membranes may have a surface area in which the contribution of the sub-micron particles (i.e., the opaloid) within the pore volume of the microporous polymer scaffold comprises from about 20% to about 30%, or about 20% to about 40%, or about 20% to about 50%, or about 20% to about 60%, or about 20% to about 70%, or about 20% to about 80%, or about 20% to about 90%. The composite membranes may have a surface area in which the contribution of the sub-micron particles (i.e., the opaloid) within the pore volume of the microporous polymer scaffold comprises from about 30% to about 40%, or about 30% to about 50%, or about 30% to about 60%, or about 30% to about 70%, or about 30% to about 80%, or about 30% to about 90%. The composite membranes may have a surface area in which the contribution of the sub-micron particles (i.e., the opaloid) within the pore volume of the microporous polymer scaffold comprises from about 40% to about 50%, or about 40% to about 60%, or about 40% to about 70%, or about 40% to about 80%, or about 40% to about 90%. The composite membranes may have a surface area in which the contribution of the sub-micron particles (i.e., the opaloid) within the pore volume of the microporous polymer scaffold comprises from about 50% to about 60%, or about 50% to about 70%, or about 50% to about 80%, or about 50% to about 90%. The composite membranes may have a surface area in which the contribution of the sub-micron particles (i.e., the opaloid) within the pore volume of the microporous polymer scaffold comprises from about 60% to about 70%, or about 60% to about 80%, or about 60% to about 90%, or about 70% to about 80%, about 70% to about 90%, or about 80% to about 90%, or about 85% to about 90%.

[0221] The composite membrane may have a contact thickness of equal to or less than about 150 pm. The composite membrane may have a contact thickness ranging from about 1 pm to about 150 pm, or from 2 pm to about 100 pm, or from about 2 pm to about 90 pm, or from about 2 pm to about 80 pm, or from about 2 pm to about 75 pm, or from about 3 pm to about 75 pm, or from about 4 pm to about 75 pm, or from about 5 pm to about 75 pm, or fromP390218USP 3252US01about 5 pm to about 70 pm, or from about 5 pm to about 65 pm, or from about 5 pm to about 60 pm, or from about 5 pm to about 55 pm, or from about 10 pm to about 55 pm, or from about 10 pm to about 50 pm, or from about 10 pm to about 45 pm, or from about 10 pm to about 40 pm. In the present disclosure, pm has its usual meaning, i.e., pm refers to micrometers or microns.

[0222] The contact thickness of the composite membrane is measured as indicated in the test methods described herein. The thickness direction of the composite membrane is the same as the thickness direction of the microporous polymer scaffold.

[0223] The composite membrane may have a volumetric scaffold filling ratio, which is the volume of the sub-micron particles (i e, the solid volume of the sub-micron particles of the opaloid within the pore volume of the microporous polymer scaffold) to the volume of the matrix of the microporous polymer scaffold (i.e., the volume occupied by the solid matrix of the microporous polymer scaffold excluding its pore volume), of from about 0.7 and about 1.1. The composite membrane may have a volumetric scaffold filling ratio of from about 0.75 and about 1.05, or from about 0.8 and about 1.

[0224] The composite membrane may comprise a plurality of microporous polymer scaffolds. The number of microporous polymer scaffolds is not particularly limited, and the composite membrane may comprise one microporous polymer scaffold, or two microporous polymer scaffolds, or three microporous polymer scaffolds, or four microporous polymer scaffolds, or from 1 and 20 microporous polymer scaffolds, or from 1 and 10 microporous polymer scaffolds. The microporous polymer scaffolds may be essentially identical, or they may be different. The potential combinations of microporous polymer scaffolds is not particularly limited. For example, the plurality of microporous scaffolds may comprise a first microporous polymer scaffold made of a first polymer (e.g., ePTFE), and a second microporous polymer scaffold made of a second polymer (e.g., ePE). Incorporating more than one type of microporous polymer scaffold into a membrane-reinforced opaloid may confer specific benefits. For example, a low-melting scaffold (e.g., ePE) may be combined with a much more thermally stable scaffold (e.g., ePTFE) to provide mechanical integrity at elevated temperature. At least one of the plurality of microporous polymer scaffolds may have a bubble point pressure of equal to or greater than two (2) bar, and the sub-micron particles incorporated within the scaffold pore volume.

[0225] The composite membrane may comprise other layers and components besides the microporous polymer scaffold and the sub-micron particles, such that the composite membrane is suitable for its intended function.P390218USP 3252US01Additional Properties of MROs

[0226] The following description of properties of the membrane reinforced opaloids of the present disclosure are applicable to all embodiments, examples and aspects of the composite membranes, systems for use as electrochemical separators, electrochemical devices, supported liquid membranes and methods described herein.

[0227] The composite membranes of the present disclosure may exhibit a first peak in tensile force versus displacement, as indicated by the triangles on Figure 30a, Figure 30b, and Figure 30c. This tensile peak may correspond to a significant fracturing or yielding of the opaloid phase, indicating the long-range extent of the opaloid along the gauge length of the tensile test The gauge length was 195 mm, and the gauge width was 2 5 mm

[0228] As shown by Figure 30a, Figure 30b, and Figure 30c, the composite membranes of the present disclosure may have a tensile strength that is substantially the same as a tensile strength of the microporous polymer scaffold when measured on an absolute basis (i.e., units of Newtons / mm, where the millimeters refers to the sample width), but the strength may be higher or lower than the original (e.g., unimbibed) microporous polymer scaffold. The absolute strength (AS) of the microporous polymer scaffold may be calculated from its matrix tensile strength (MTS), mass-per-area (MpA), and skeletal density (ps) as follows.AS = MTS * (MpA / ps)

[0229] Tensile testing may be used to assess the presence of continuous opaloid phases in composite articles. As indicated by the triangles in Figure 30a, Figure 30b, and Figure 30c, tensile testing of composite membranes and subsequent analysis demonstrated a first tensile peak (e.g., yield point ) that may be associated with the yielding of a continuous opaloid phase with macroscopic extent. The strain associated with this peak may be referred to as the composite opaloid yield strain. The presence of the first tensile peak (which may be referred to as the opaloid yield peak) may be an indication that the opaloid extends macroscopically in the direction of the tensile pull by at least a length equivalent to the gauge length.

[0230] The composite membranes of the present disclosure may have a Young’s modulus that is larger than a Young’s modulus of the original microporous polymer scaffold (e.g., before fabrication of the MRO). For example, the composite membrane may have a Young’s modulus that is at least two times larger, or at least three times larger than the Young’s modulus of the microporous polymer scaffold.

[0231] Tensile properties may contribute to improved handling and durability in applications (e.g., in industrial applications as described below). For example, Figure 30a, Figure 30b, and Figure 30c show that the composite membranes may have a break strainP390218USP 3252US01that is significantly larger than the composite opaloid yield strain. A large difference between the break strain and the composite opaloid yield strain may enable the composite membrane to avoid catastrophic failure (e.g., it may fail more slowly and / or predictably, enabling appropriate monitoring and / or intervention). The ratio of the break strain divided by the composite opaloid yield strain may be at least about 1.2, or at least about 1.4, or at least about 1.6, or at least about 1.8, or at least about 2.0, or at least about 2.5, or at least about 3.0, or at least about 4, or at least about 5, or at least about 6, or at least about 7, or at least about 8, or at least about 9, or at least about 10, or at least about 12, or at least about 14, or at least about 16, or at least about 18, or at least about 20. The ratio of the break strain divided by the composite opaloid yield strain may be about 1.2 to about 20, or about 1.4 to about 20, or about 1.6 to about 20, or about 1.2 to about 18, or about 1.4 to about 18, or about 1.6 to about 18, or about 1.2 to about 16, or about 1.4 to about 16, or about 1.6 to about 16, or about 1.2 to about 14, or about 1.4 to about 14, or about 1.6 to about 14, or about 1.2 to about 12, or about 1.4 to about 12, or about 1.6 to about 12, or about 1.2 to about 10, or about 1.4 to about 10, or about 1.6 to about 10. Furthermore, the higher Young’s modulus of the composite membranes relative to the original scaffold may contribute to improved handleability because, for example, the composite membrane may be less prone to wrinkling than the original scaffold. Furthermore, the composite membranes may exhibit significantly lower Young’s modulus and / or higher ductility than the neat opaloid, which may be characterized by high modulus and / or low displacement before brittle failure. The lower Young’s modulus and / or higher ductility of the composite membranes (relative to the neat opaloid) may contribute to improved handleability because, for example, the composite membrane may be less prone to breaking during installation or use. Thus, the composite membranes may exhibit improved handleability compared to either a neat opaloid or the microporous polymer scaffold alone.

[0232] The composite membrane may have low compressibility (i.e., the composite membrane resists compression under mechanical load). One non-limiting way to quantify compressibility under load is by the ratio of the contact thickness, Tc, to the non-contact thickness, TNC (i.e., Compressibility (%) = (1 - TC / TNC) ■ 100). The compressibility of the composite membrane as determined in this manner may be from about 0.2% to about 1%, or about 0.2% to about 3%, or about 0.2% to about 5%, or about 0.2% to about 10%, or about 0.2% to about 15%, or about 0.2% to about 20%, or about 0.2% to about 25%, or about 0.2% to about 30%, or about 0.2% to about 40%, or about 0.2% to about 50%, or about 0.2% to about 60%, or about 0.2% to about 70%, or about 0.2% to about 80%. The compressibility of the composite membrane may be from about 0.5% to about 1%, or about 0.5% to about 3%, or about 0.5% to about 5%, or about 0.5% to about 10%, or about 0.5% to about 15%, or about 0.5% to about 20%, or about 0.5% to about 25%, or about 0.5% to about 30%, or about 0.5%P390218USP 3252US01to about 40%, or about 0.5% to about 50%, or about 0.5% to about 60%, or about 0.5% to about 70%, or about 0.5% to about 80%. The compressibility of the composite membrane may be from about 1% to about 3%, or about 1% to about 5%, or about 1% to about 10%, or about 1% to about 15%, or about 1% to about 20%, or about 1% to about 25%, or about 1% to about 30%, or about 1% to about 40%, or about 1% to about 50%, or about 1% to about 60%, or about 1% to about 70%, or about 1% to about 80%. The compressibility of the composite membrane may be from about 3% to about 5%, or about 3% to about 10%, or about 3% to about 15%, or about 3% to about 20%, or about 3% to about 25%, or about 3% to about 30%, or about 3% to about 40%, or about 3% to about 50%, or about 3% to about 60%, or about 3% to about 70%, or about 3% to about 80%. The compressibility of the composite membrane may be from about 5% to about 10%, or about 5% to about 15%, or about 5% to about 20%, or about 5% to about 25%, or about 5% to about 30%, or about 5% to about 40%, or about 5% to about 50%, or about 5% to about 60%, or about 5% to about 70%, or about 5% to about 80%. The compressibility of the composite membrane may be from about 10% to about 15%, or about 10% to about 20%, or about 10% to about 25%, or about 10% to about 30%, or about 10% to about 40%, or about 10% to about 50%, or about 10% to about 60%, or about 10% to about 70%, or about 10% to about 80%. The compressibility of the composite membrane as determined in this manner may be from about 15% to about 20%, or about 15% to about 25%, or about 15% to about 30%, or about 15% to about 40%, or about 15% to about 50%, or about 15% to about 60%, or about 15% to about 70%, or about 15% to about 80%. The compressibility of the composite membrane as determined in this manner may be from about 20% to about 25%, or about 20% to about 30%, or about 20% to about 40%, or about 20% to about 50%, or about 20% to about 60%, or about 20% to about 70%, or about 20% to about 80%. The compressibility of the composite membrane as determined in this manner may be from about 30% to about 40%, or about 30% to about 50%, or about 30% to about 60%, or about 30% to about 70%, or about 30% to about 80%, or about 40% to about 50%, or about 40% to about 60%, or about 40% to about 70%, or about 40% to about 80%, or about 50% to about 60%, or about 50% to about 70%, or about 50% to about 80%, or about 60% to about 70%, or about 60% to about 80%, or about 70% to about 80%.Fabrication of MROs

[0233] The following passage describes in more detail some example methods by which MROs may be produced. It is intended to provide guidance to one of ordinary skill in the art to facilitate production of MROs but should not be construed as being limited to a particular embodiment or aspect.P390218USP 3252US01

[0234] Fabricating a composite membrane by providing a microporous polymer scaffold and depositing the opaloid in the pores of the microporous polymer scaffold may be preferred over other methods (e.g., co-extrusion or co-deposition of particles with a polymeric binder, or compounding the particles with loose fibers because, for example, the strength of the composite membrane (e.g., the tensile strength of the composite membrane per unit of mass or per unit thickness) may be significantly increased. The MRO may be produced by incorporating the sub-micron particles into the microporous polymer scaffold via a method that comprises imbibing. As used herein, the term “imbibing” refers to a process of depositing a material within the pores of a microporous polymer scaffold using a liquid carrier, but not substantially incorporating the imbibed material into the matrix of the microporous polymer scaffold, such that the microporous polymer scaffold remains largely intact. For example, the microporous polymer scaffold may be wetted with an imbibing fluid, where the imbibing fluid comprises the sub-micron particles and a liquid carrier. To achieve a high loading of opaloid in the MRO, a high concentration of sub-micron particles in the imbibing fluid may be used (e.g., in some embodiments, the imbibing fluid may be prepared with minimal dilution of the sub-micron particles). As used herein, a microporous polymer scaffold that is “wetted” with a fluid has some or all of its pores filled with the fluid. The wetted microporous polymer scaffold may then be dried, such that the liquid carrier is substantially removed, resulting in the submicron particles being deposited within the pores of the microporous polymer scaffold. As will be appreciated by one skilled in the art, to produce an MRO a variety of imbibing conditions must be chosen so that the material deposited in the pores comprises an opaloid (e.g., the concentration of sub-micron particles in the liquid carrier within the pores, the packing density the sub-micron particles are enabled to achieve in the pores (e.g., enabled in part by a high colloidal stability of the colloidal precursor), the ratio of the volume of sub-micron particles in the pores to the skeletal and total volume of the microporous polymer scaffold, and the distribution of the imbibing fluid in the microporous polymer scaffold).

[0235] The imbibed microporous polymer scaffold may be dried by heating it to a high temperature, such as to 250°C, fora sufficient period of time such as 1 minute to 120 minutes. It will be appreciated by one of ordinary skill in the art that other conventional drying methods may be used, and that drying conditions, in particular time and temperature, may be modified depending on the needs of the process and on the limitations of the materials (e.g., including their melting points and / or glass transition temperatures and / or decomposition temperatures). The method may further comprise a step of heat treating the dried MRO.

[0236] The sub-micron particles may be imbibed into the microporous polymer scaffold from one side of the microporous polymer scaffold (e.g., by applying a thin film of the imbibing fluid on one side of the microporous polymer scaffold via Mayer bar coating), or from both sides (first and second surfaces) of the microporous polymer scaffold (e.g., by dip coating theP390218USP 3252US01microporous polymer scaffold in the imbibing fluid). The sub-micron particles may be imbibed such that the opaloid is substantially contained within the pores of the microporous polymer scaffold (i.e., the thickness of opaloid deposited on the first or second surface of the microporous polymer scaffold, outside the pore volume of the microporous polymer scaffold, sometimes referred to as “buttercoat” layers, is minimal). The thickness of a minimal buttercoat layer may be less than 2 microns, or less than 1 micron, or less than 0.5 microns, or less than 0.2 microns, or less than 0.1 microns.

[0237] The imbibing process may comprise a backer that is a film or fabric, such as a woven material or a non-woven material, such as a web, that serves as a processing aid in the production of the MRO by physically supporting it through at least a portion of the imbibing process. The use of a backer may enable a higher loading of opaloid in the microporous polymer scaffold. The backer may be a polymer film. The imbibing process may comprise a step in which the microporous polymer scaffold wetted with imbibing fluid is in contact with the backer. The backer may be adhered to the M O, and the force of adhesion may be such that the backer can be removed from (e.g., peeled off of) the MRO without substantially damaging the MRO.

[0238] The liquid carrier in the fluid is not particularly limited, and any suitable liquid carriers known in the art may be used. Suitable liquid carriers may include water and organic liquids. Organic liquids may include alcohols and mixtures of alcohols (such as a C1-C5 alcohols), dimethyl sulfoxide, dimethyl acetamide, acetonitrile, toluene, dimethyacetamide (DMAc), methyl ethyl ketone (MEK), acetone, dimethylformamide (DMF), tetrahydrofuran (THF), and N-methyl-2-pyrrolidone (NMP). More than one liquid carrier may be used, such as two, or three, or four liquid carriers. The C1 -C5 alcohol (e.g., isomers of methanol, ethanol, propanol, butanol, and pentanol) may be any one selected from methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, pentan-1 -ol, and a combination thereof.

[0239] If the imbibing fluid does not spontaneously and readily wet the microporous polymer scaffold, then a variety of techniques may be employed to assist in achieving good wetting, such as by applying a differential pressure to force the liquid into the microporous polymer scaffold, raising the temperature of the liquid to lower its viscosity and surface tension, and / or pre-wetting the microporous polymer scaffold with another miscible liquid. As described above, imbibing microporous polymer scaffolds, especially low surface energy scaffolds, relies on good wetting. " Wetting" results when the contact angle, 6, between the liquid and the solid is less than about 90 degrees. Spontaneous wetting occurs when the surface energy between the solid and liquid, YSL is less than the surface energy between the solid and air, ysA. The typical relationship between these parameters and the liquid-air surfaceP390218USP 3252US01energy, yLA(i e., the surface tension of the liquid), is given by the relationship below (Young’s equation):YSL = YSA - YLA*COS(6)

[0240] To achieve good wetting, the surface tension of the imbibing fluid should be sufficiently low to penetrate the microporous polymer scaffold. For example, a surface tension of less than or equal to about 30 dynes / cm is typically required to penetrate expanded microporous PTFE. Higher surface tension imbibing fluids may accordingly be suitable for higher energy scaffolds such as microporous polyethylene or microporous polypropylene.

[0241] Imbibing fluids that are aqueous or substantially aqueous are preferred in some cases, for example because of the availability of stable and highly concentrated colloidal dispersions, or because of safety and environmental reasons. For example, when the submicron particles comprise a ceramic or glass then an aqueous or substantially aqueous imbibing fluid may be preferred to minimize the need for oligomeric or polymeric dispersing agents. To enable an aqueous or substantially aqueous imbibing fluid to wet a microporous polymer scaffold with minimal dilution, a suitable wetting agent may be emulsified in the aqueous or substantially aqueous imbibing fluid with the aid of a surfactant. Suitable wetting agents include alcohols and mixtures of alcohols that exhibit a low water solubility, such as those alcohols having five to ten carbon atoms in the longest continuous chain, e.g., alcohols with C5-C10 linear chains, and the like. For example, pentanols, hexanols, octanols, and the like, are within the range of suitable wetting agents. Herein, these wetting agents may be referred to as “insoluble alcohols.” Similarly, suitable wetting agents also include carboxylic acids and mixtures of carboxylic acids that exhibit a low water solubility, such as those carboxylic acids having five to ten carbon atoms in the longest continuous chain, e.g., carboxylic acids with C5-C10 linear chains, and the like. For example, pentanoic acid, hexanoic acid, octanoic acid, and the like, are within the range of suitable wetting agents. Herein, these wetting agents may be referred to as “insoluble carboxylic acids.” Such insoluble wetting agents are most effective when present in the imbibing fluid above their solubility limit so as to form an “oil phase” that may be emulsified. Further, the imbibing fluid can incorporate with the water insoluble alcohol(s) and / or carboxylic acid(s) other water insoluble organics, such as alkanes, etc. In some embodiments, the wetting agent may also exhibit a low ysi_ relative to the targeted low surface energy scaffold.

[0242] The surfactant(s) can be a single surfactant or a combination of surfactants. Suitable surfactants are defined as those that are able to emulsify the desired wetting agent. For example, for the alcohols described above, several classes of anionic surfactants can be used, including, but not limited to, those having a structure of R(EO)nOSO3‘ or ROSC where R can be any organic chain, " O" is oxygen, " S" is sulfur, " EO" is ethylene oxide and n>1. In anP390218USP 3252US01alternate embodiment, non-ionic surfactants having the structure R(EO)nOH, where n>1, are also suitable for this invention. In a preferred embodiment, nonionic surfactants with hydrophilic-lipophilic balance (" HLB") values of ten or greater were found most effective to emulsify the wetting agents described above. The concentration of surfactant can be adjusted in order to achieve good emulsification of the desired wetting agent. For example, when 4% by weight of n-hexanol wetting agent (based on the total aqueous solution weight) is used, a concentration of about 2 wt% of sodium dodecyl ether sulfate was found to be suitable. In an alternate formulation, 6 wt% of an ethoxylated alcohol was able to emulsify 4 wt% n-hexanol wetting agent. Other examples of suitable surfactants include Tergitol™ TMN10 and Barlox™ 8S.

[0243] In addition to the aqueous delivery system provided by the surfactant and the wetting agent, a stabilizing agent can be added. A stabilizing agent is typically soluble in both the wetting agent and water, and it allows a greater amount of wetting agent to be stabilized in the aqueous system than without the stabilizer. In one embodiment, glycols were found to be effective stabilizers, such as but not limited to dipropylene glycol (" DPG"), dipropylene glycol monomethyl ether, and propylene glycol. A wide range of stabilizer concentrations can be used depending on the amount of additional stability desired. For instance, if a small increase in stability is desired, a small amount of the stabilizer should be used. Conversely, higher stabilizer concentrations generally further increase the emulsion stability. Exceptions to these general guidelines do however exist. For example, DPG may be an effective stabilizer when used in concentrations ranging from less than about 1% wt. up to about 10% wt. based on total aqueous emulsion weight for hexanol-based systems

[0244] The imbibing fluid may contain additives such as dispersing agents to stabilize the colloidal dispersion or colloidal suspension. The purpose of such dispersing agents is typically to reduce viscosity, reduce or prevent agglomeration of particles, and / or reduce or prevent settling of particles. Preparation of the colloidal dispersion or colloidal suspension, and maintaining the particles as suspended or dispersed, may require the use of high-shear mixing. Various means of high-shear mixing for the preparation of colloidal dispersions and colloidal suspensions are available and are well-known to those of ordinary skill in the art, such as rotor-stators, Cowles mixers, wet jet mills, and media mills.Applications including Supported Liquid Membranes (SLMs)

[0245] As described above, MROs of the present disclosure have an extraordinary set of properties that may enable high performance in a variety of applications. Such applications may include filtration media and electrochemical separators. The inventors have also recognized that the list of desirable properties above may make MROs a nearly ideal membrane support for so-called Supported Liquid Membranes (SLMs), especially MROsP390218USP 3252US01comprising sub-micron particles that comprise ceramics and / or glasses. A supported liquid membrane is a membrane system where a liquid is immobilized within the pores of a microporous membrane, typically via capillary forces. In use, SLMs are typically not submerged in the supported liquid; instead, the supported liquid is contained in the pores of the membrane support, while outside of the SLM (e.g. adjacent to the SLM) there may be, for example, a gas phase or other fluid that is immiscible with the supported liquid. SLMs have been explored for a wide variety of applications including gas separation and electrochemical separators. The extremely small pores, relatively high porosity, crush resistance, and wettability may enable composite membranes (MROs) of the present disclosure to durably retain relatively large amounts of liquid even when subjected to high differential pressure and high compressive stress. Furthermore, the chemical and thermal stability of the MROs of the present disclosure may make them suitable for applications in challenging environments.

[0246] In some embodiments, the supported liquid within the SLM must be able to remain in the pores of the support even if subjected to significant compression or to a significant pressure drop across the SLM (i.e., a significant trans-membrane pressure). For example, the liquid may be retained within the composite membrane pores via capillary forces. The liquid may be retained in the composite membrane pores when subjected to significant transmembrane pressure, for example a trans-membrane pressure of at least between about 1 bar to about 28 bar, or between about 5 bar to about 25 bar, or between about 10 bar to about 20 bar, or about 2 bar to about 15 bar, or about 7 bar to about 28 bar.

[0247] The supported liquid in the SLM may also have adequate durability for the intended application (e.g., the liquid itself does not unacceptably degrade when exposed to the thermal, chemical, electrochemical, radiation, and other stresses of the intended application). The liquid may comprise high-performance fluids such as ionic liquids, deep eutectic solvents, or low-vapor-pressure oils. Ionic liquids can, for example, be liquid at less than about 100°C (i.e., so-called “room-temperature ionic liquids” or RTILs), have tuneable properties such as viscosity and solubility, and can be stable at high voltage and / or high temperatures.

[0248] Furthermore, the membrane support for the liquid must also have adequate durability (e.g., chemical and mechanical durability) to survive in the intended application without unacceptable loss of function. In some embodiments, it will also be readily wettable with the liquid to be supported.

[0249] The composite membrane (i.e., the MRO) may be a membrane support for a supported liquid membrane. In some embodiments, the composite membranes having submicron particles with a particle diameter of from about 1 to 100 nm, or about 2 to 80 nm, or about 3 to 60 nm, or about 4 to 40nm, or about 5 to 35 nm, or about 5 to 30 nm, or about 5 toP390218USP 3252US0125 nm may be a membrane support for a supported liquid membrane. The membrane support for the SLM may comprise sub-micron particles that comprise a ceramic and / or a glass.

[0250] The composite membrane may further comprise a liquid within the composite membrane pores. The liquid may have adequate durability (e.g., regarding thermal, chemical, electrochemical, radiation, and other stresses).

[0251] The composite membrane pores may be substantially filled or partially filled with the liquid. In some embodiments, the SLM has no residual porosity, meaning the liquid has completely filled the pore volume of the membrane support of the SLM. In some embodiments, the SLM has up to 5% residual porosity. In some case the residual porosity is up to 1%, up to 2%, up to 3%, up to 5%, up to 7%, up to 10%, up to 15%, up to 20%, up to 25%, up to 30% up to 40 or up to 45% or up to 50% or up to 60% or up to 70% or up to 80% or up to 90% or up to 95% or up to 98% or up to 99%.

[0252] The liquid may be retained within the composite membrane pores.

[0253] There are numerous methods by which an MRO could be used in the fabrication of a SLM. In one embodiment, an MRO is first fabricated. Then the pores of the MRO are filled with the liquid to be supported. The pores may be filled with the liquid by spontaneous wetting, or the wetting may be assisted by any of a variety of means that will be evident to one of ordinary skill in the art, such as by applying a differential pressure to force the liquid into the MRO, raising the temperature of the liquid to lower its viscosity and surface tension, prewetting the MRO with another miscible liquid, and so on. As described above, non-limiting examples of high-performance liquids to be supported in the SLM may include deep eutectic solvents, low-vapor-pressure oils, and ionic liquids (ILs) including room-temperature ionic liquids (RTILs). Such high-performance liquids are typically customized to the desired application based on, for example, their durability in the application as well as other properties such as transport properties (e.g., ionic conductivity, selective ionic conductivity, gas permeability, selective gas permeability, solute permeability, selective solute permeability, and so on).Volumetric vs. Gravimetric Basis

[0254] When fabricating composite materials, mass-based formulations and mass-normalized units (e.g., specific surface area expressed in cc / g) are often used for convenience. However, when designing and analyzing composite materials, the volume fraction of different components is often more meaningful than mass fraction. For example, thickness and porosity, which are inherently volumetric properties, are important considerations to the calculation of permeance and conductance. As another example, matrixP390218USP 3252US01tensile strength (MTS), which is effectively a volume-normalized version of tensile strength, is a critical parameter for characterizing both the microporous polymer scaffold and the composite membrane (i.e., the MRO). To account for the differences in the skeletal densities of different components (e.g., different microporous polymer scaffolds and different submicron particles), the inventors believe that volume-normalized units may be preferred over other conventions such as mass-normalized units in some cases.

[0255] An example of a property that may be best expressed in volume-normalized units is the (mass-)specific pore volume. By multiplying the customary gravimetric units (i.e., ccpore / gsoiid) by the skeletal density (expressed in gSoiid / ccSOiid) the volume-specific pore volume (expressed in ccPore / ccSoiid) may be obtained. The relationship between volume-specific pore volume and porosity is shown in Figure 31. This plot illustrates the ideal level of porosity that may be achieved by the opaloids in the MROs of the present disclosure, as follows. The graph may be divided into three regions: 1) a concave-down region for low values of porosity, 2) the region surrounding the inflection point at 50 vol% porosity, and 3) a concave-up region for high values of porosity. Composite membranes in Region 1 shown in Figure 31 may have unfavorable properties because their porosity is too low (e.g., low ion conductance), and they may be challenging to fabricate due to the difficulty of achieving such extremely high packing densities (e.g., denser than the theoretical limit of 26 vol% porosity for monodisperse spheres arranged in a hexagonal close-packed structure). Conversely, composite membranes in Region 3 may lack structural integrity (e.g., crush resistance) and be hard to fabricate and handle, especially in thin form factors, because of the extremely large amount of void volume per unit of solid (i.e., per unit of structure-defining material elements). Composite membranes in Region 2 may be preferred because the level of porosity is high enough to enable effective transport (e.g., high ion conductance and / or good mass transport), but the level of porosity is still low enough to maintain good structural integrity.Electrochemical Separators

[0256] An electrochemical device comprises an electrochemical cell. Examples of electrochemical devices include electrolyzers (e.g., water electrolyzers such as liquid alkaline water electrolyzers), and redox flow batteries (e.g., vanadium redox flow batteries). Simplified cell diagrams of these two devices are depicted in Figures 33a and 33b, respectively. An electrochemical cell may comprise an anode, a cathode, and an electrochemical separator. For rechargeable batteries like redox flow batteries, the electrodes may be referred to as the negative and positive electrodes, where the typical convention is that the negative electrode (sometimes referred to as the anode) acts as an anode when the electrochemical cell is discharging and a cathode when the electrochemical cell is charging, and the positive electrode (sometimes referred to as the cathode) acts as a cathode when the electrochemicalP390218USP 3252US01cell is discharging and an anode when the electrochemical cell is charging (i.e., the electrodes in rechargeable batteries are sometimes named for their role during discharge). An electrochemical separator is a material, for example a membrane or diaphragm, that may prevent electrical contact between the anode and cathode within an electrochemical cell, thus reducing the risk of a short circuit, while allowing ion conduction between the anode and cathode by means of an electrolyte. Electrochemical separators may be configured in a variety of forms, most commonly as a web (i.e., a long, thin, flexible material typically supplied in roll form), or a sheet (e.g., a flat sheet), but other forms such as a tube (e.g., a round tube) are also possible depending on the design of the electrochemical cell. Foran electrochemical separator to function properly, an electrolyte must be integrated with the separator to enable ion conduction through the separator (i.e., efficiently between the anode and cathode). Separators may also be required to perform other critical functions, such as preventing chemical species (e.g., gases or ions) or other materials from “crossing over” between the anode and cathode sides of the cell (i.e., transporting across the separator).

[0257] To improve the overall performance or economics of an electrochemical device, it may be desirable to improve the effectiveness of the separator in a variety of ways (“improvement vectors”). For example, it may be desirable to:1) Make the separator thinner and thereby reduce ionic resistance and improve the volumetric and gravimetric energy density of the electrochemical device.2) Increase the compressive pressure the separator can withstand without short circuiting, e.g., to improve the safety of the electrochemical device, or to enable higher compressive loads and thereby improve the performance of the electrochemical device by reducing contact resistances within the electrochemical cell.3) Reduce unwanted crossover of reactive species or other materials through the separator and thereby improve the safety of the electrochemical device and enhance the operational flexibility of the electrochemical device.4) Improve the handleability of the separator e.g., to enable efficient processing, shipping, handling, storage, and installation of the separator in the final application (i.e., in the electrochemical cell in the electrochemical device), simplifying logistics and thereby facilitating scale-up and cost-reduction of the electrochemical device.5) Enhance the operable temperature range of the separator, which may improve the performance of the electrochemical device by enabling higher-temperature operation (resulting in e.g., faster electrode kinetics and / or higher electrolyte conductivity within the electrochemical cell).6) Improve the dimensional stability of the separator at high temperature and thereby improve the safety of the electrochemical device by preventing catastrophic failure during e.g., a puncture of the electrochemical cell.P390218USP 3252US01

[0258] These goals are often in tension, in particular item #1 may conflict with items #2 -#4. Such tensions result in so-called “engineering trade-offs” between separator attributes, which may be embodied in ratios for a given separator, such as the ratio of ionic conductance to degree of protection against short circuits, or the ratio of ionic conductance to gas or liquid permeance.

[0259] In the present disclosure, the inventors have surprisingly discovered that membrane reinforced opaloids may possess highly advantageous combinations of attributes that simultaneously enable some or all of the improvement vectors enumerated above, making them preferred separators for electrochemical cells in a variety of applications and configurations. The forthcoming paragraphs will describe advantages of using MROs of the present disclosure as electrochemical separators.Redox Flow Batteries

[0260] Figure 33a depicts the simplified cell diagram of a Vanadium Redox Flow Battery (VRFB) 30, which may comprise a negative-side flow plate 31, a negative electrode (or anode) 32, a separator 34, a positive electrode (or cathode) 38, and a positive-side flow plate 36. An exemplary half-cell reaction for the negative electrode is as follows (right-facing arrow shows discharging): V2+l3++ e~. An exemplary half-cell reaction for the positive electrode is as follows (right-facing arrow shows discharging): VO2+ 2 / / ++ e~ VO2++ H2O. Negative electrolyte (sometimes called anolyte) comprising V2+and V3+may circulate on the negative side of the cell (e.g., through the negative-side flow plate 31 and the negative electrode 32), and positive electrolyte (sometimes called catholyte) comprising VO2and VO2+may circulate on the positive side of the cell (e.g., through the positive-side flow plate 36 and the positive electrode 38). VRFBs are a candidate for large-scale grid storage of electricity, which is needed to facilitate greater adoption of intermittent sources of renewable electricity (e.g., wind and solar). To achieve industry cost targets it is desirable to maximize the Energy Efficiency (EE) of a VRFB. EE (expressed as e.g., an energy %) is the product of Voltage Efficiency (VE, expressed as e.g., a voltage %) and Current Efficiency (CE, expressed as e.g., a coulombic percent) as follows: EE = CE * VE. VE may account for parasitic voltage losses (such losses are typically expressed in, for example, mV). VE may be increased by, for example, lowering contact resistances in the cell, or by lowering the ionic resistance (in particular the ionic resistance for the transport of protons, H+) of the separator. CE may account for parasitic current losses that cause charge imbalance between the charging and discharging phases of cell operation (such losses are typically expressed in, for example, amp-hours per cm2of active area or as a coulombic percent) CE may be increased by, for example, reducing the crossover of vanadium ions across the separator. From the preceding discussion, it may be evident that to maximize the VE (and by extension the EE) of a VRFB,P390218USP 3252US01it is desirable for a separator to enable improvement in the ratio of proton conductance to degree of protection against short circuits (i.e., to increase proton conductance while also increasing protection against short circuits), which will be referred to as the “Conductance / Shorting” trade-off. The following paragraphs will describe how MROs enabled an improvement in the state of the art for this key engineering trade-off.

[0261] Multiple cell designs are used for VRFBs in industry, and increasingly so-called “zero gap” designs are being employed, in which the negative electrode 32 and / or positive electrode 38 are in direct contact with and exert compressive pressure on the separator 34. Protection against short circuits (also called “shorting protection”) was therefore evaluated using the Force-Displacement-Resistance (FDR) test as described herein. Figure 34 shows a depiction of the test setup. Proton resistance was evaluated using the Proton Area-Specific Resistance (H+ASR) test as described herein.

[0262] As comparative examples, two reinforced polymer electrolyte membranes (or reinforced PEMs) were fabricated as described in Examples 27 and 28. W. L. Gore and Associates, Inc. is widely recognized as the world leader in reinforced PEMs, and the inventors consider these reinforced PEMs to be at or beyond the state of the art for VRFB separators. These materials were compared to two sets of Inventive Examples.

[0263] The first such set of Inventive Examples consists of Examples 29, 30, and 12. These examples pertain to MROs with thicknesses of about 2.5, 4.5, and 9.6 microns, respectively. All three MROs comprised silica sub-micron particles with diameter approximately 7 nm, and ePTFE microporous polymer scaffolds with bubble points of about 7.6 bar. For all three MROs, the microporous polymer scaffolds were imbibed with sub-micron particles from both sides, resulting in MROs with superior wettability even in aqueous electrolyte (such wettability may be important to enable the integration of electrolyte with the separator, in this case liquid electrolyte disposed in the pores of the MROs, to enable efficient ion conduction across the separator).

[0264] The second such set of Inventive Examples consists of Examples 25 and 26. These examples each pertain to a multi-layer separator comprising a layer of polymer electrolyte sandwiched between two MROs (i.e., “MRO / PEM Multilayer Separators”). In both examples, the central layer of polymer electrolyte comprises an approximately 2-micron thick layer of perfluorosulfonic acid (PFSA) with an equivalent weight (EW) of about 720 g / eq. The MROs layers of Example 25 are each about 4 microns thick, and the MRO layers of Example 26 are each about 8 microns thick. The sample fabrication is illustrated in Figure 35, and described in detail in the examples. For the MROs in both examples, the microporous polymer scaffolds were imbibed with sub-micron particles from both sides, resulting in MROs with superior wettability even in aqueous electrolyte (such wettability may be important to enableP390218USP 3252US01the integration of electrolyte with the separator, in this case liquid electrolyte disposed in the pores of the MRO, to enable efficient ion conduction across the separator).

[0265] The shorting protection and H+ASR results are shown in Table 3, and in Figure 36. As shown in Figure 36, two response variables were calculated from the FDR Data. The first response variable is the lowest pressure at which 8% or more of the test samples shorted, as shown in Figure 36a. Each data point is labeled with the corresponding example number. It is desirable for the data to be in the upper left corner of this plot (i.e., high shorting pressure and low H+ASR). The dashed line through each set of materials is a guide-to-the-eye that approximates the “Conductance / Shorting" trade-off for that set of materials. It is evident from the figure that the MRO Separators show a substantial shift “to the left” relative to the Comparative Examples, indicating that they have significantly lower H+ ASR at equivalent shorting protection. The data for these materials in Table 3 also makes it evident that the shorting protection for the MRO separators is superior to the Reinforced PEMs at equivalent thickness (e.g., the MRO in Example 12 and the Reinforced PEM in Example 27 are both about 8 microns thick, but the MRO can withstand about twice the shorting pressure at an 8% failure rate). The data for the MRO / PEM Multi-layer Separators show an even more dramatic improvement in the “Conductance / Shorting” trade-off, displaying a large shift “up” relative to the Comparative Examples, indicating that they have a significantly higher shorting protection at equivalent H+ASR. The improvement in shorting protection enabled by the MRO layers is highlighted by the comparison of Examples 28 (Reinforced PEM), 12 (MRO Separators), and 25 (MRO / PEM Multi-Layer Separators), all of which have similar H+ASR, but the samples comprising MRO samples had significantly better shorting protection than the comparative example (e.g., by a factor of 1.5x to 2x for the MRO separators, and by a factor of about 5x for the MRO / PEM Multi-layer Separators). Note that the maximum pressure achievable in the FDR test was 420 psi, and Example 26 (of the MRO / PEM Multi-layer Separator group) consistently maxed out the test, so the improvement in the “Conductance / Shorting” trade-off may actually be under-estimated for this group of materials in this test. Figure 36b shows a different response variable on the y-axis: the average pressure at which the sample shorted. The signals observed in Figure 36b are similar to those already discussed for Figure 36a.This data has been included to illustrate that the conclusions are robust to different failure criteria (i.e., the conclusions did not substantially change when the failure criteria was changed from 8% failure pressure to average failure pressure).Liquid Alkaline Water Electrolysis

[0266] Figure 33b depicts the simplified cell diagram of a Liquid Alkaline Water Electrolyzer 40, which may comprise an anode-side transport layer 41, an anode 42, a separator 44, a cathode 48, and a cathode-side transport layer 46. In the case of liquid alkaline electrolyzers, the separator is typically a porous diaphragm (e.g., Zirfon® diaphragmsP390218USP 3252US01available from AGFA). All of these components in the electrochemical cell may be partially or fully saturated with liquid electrolyte (e.g., aqueous KOH) to enable ion conduction, and water may be fed to the electrolyzer on the cathode side. An exemplary half-cell reaction for the anode is as follows: 20H~ 02+ H20 + 2e~. An exemplary half-cell reaction for the cathode is as follows: 2H2O + 2e~ -> H2+ 2OH~. There is growing interest in using liquid alkaline water electrolysis powered by renewable energy (e.g., solar or wind) to produce H2with a low CO2 footprint (i.e., so-called “Green Hydrogen”). However, Green Hydrogen is currently too expensive, and significant improvements in the energy efficiency of liquid alkaline water electrolyzers are needed to achieve industry cost targets and enable wider adoption of Green Hydrogen.

[0267] To improve the energy efficiency of liquid alkaline water electrolysis it is desirable to lower the ionic resistance of the electrochemical separator. However, reducing the ionic resistance of the electrochemical separator, for example by making it thinner, may result in an increase in the gas or liquid permeance, which may in turn cause a number of problems. A prime example of such a problem arises due to H2 gas produced on the cathode side of the liquid alkaline water electrolyzer crossing over the separator to the anode side, where it may mix with O2 gas. If the concentration of H2gas in the O2 (sometimes described by the H2-to-O2 ratio or HTO) reaches the lower explosive limit then an explosion may occur. Therefore, liquid alkaline water electrolyzers are required to operate in regimes where the HTO remains at a safe level. It is therefore desirable for separators to have low H2crossover. One of the mechanisms by which H2 may cross over the separator is by liquid permeance through the separator. The electrolyte on the cathode side is typically saturated (or super-saturated) with H2 gas, and if a pressure gradient arises across the separator such that the cathode-side pressure is higher than the anode-side pressure, then ^-saturated electrolyte may pass through the separator from cathode side to anode side and release H2 into the O2 stream. Such a pressure imbalance may arise in a number of ways, for example due to a sudden change in operating current density (e.g., because 2 moles of H2 are produced for every 1 mole of O2, which may result in a temporary pressure spike on the cathode side). Changes in operating current density may occur, for example, due to the fluctuating availability of renewable energy sources such as solar and wind. To minimize the exchange of electrolyte across the separator in response to such pressure gradients, it may be desirable to reduce the liquid permeance of the separator.

[0268] From the preceding discussion, it may be evident that to maximize the efficiency of liquid alkaline water electrolysis (and thereby lower the cost of Green Hydrogen) it is desirable for the separator to improve the ratio of ionic conductance (i.e., OH' conductance) to liquid permeance (i.e., to increase the ionic conductance while decreasing the liquidP390218USP 3252US01permeance), which will be referred to as the “Conductance / Permeance” trade-off. It is critical to accomplish this while maintaining adequate shorting protection (which will be assessed using the shorting protection for LAWE method described herein) and handleability (for example, by ensuring adequately high tensile properties such as ultimate strength and Young’s modulus).

[0269] A set of Inventive Examples of porous diaphragms for liquid alkaline water electrolysis was produced. This set consists of Examples 31, 32, and 33. Each of these porous diaphragms is a membrane reinforced opaloid (MRO) comprising sub-micron particles of yttria-stabilized zirconia (at 3 mol% yttria) with a nominal particle diameter of about 32 nm. Example 31 comprises a porous polyethylene microporous polymer scaffold. Example 32 comprises an expanded functional copolymer-based microporous polymer scaffold. Example 33 comprises four layers of an ePTFE microporous polymer scaffold. The properties of these porous diaphragms are shown in Table 4.

[0270] As discussed earlier in the specification, MROs may be produced in which the pore volume of the microporous polymer scaffold is, for example, only partially filled by the opaloid (resulting in what may be referred to as a hierarchical pore structure), or, as another example, in which the pore volume of the microporous polymer scaffold is substantially filled by the opaloid. To illustrate this difference, Scanning Electron Microscopy (SEM) images of Examples32 and 33 are shown in Figure 37. Figures 37a and 37b show the surface and cross-section, respectively, of an MRO comprising expanded functional copolymer-based microporous polymer reinforcement. This MRO has a hierarchical structure comprising pores that have been intentionally only partially filled with opaloid, resulting in a population of larger pores interspersed throughout the porous diaphragm. These larger pores are especially evident as the large, dark voids in the cross-section image in Figure 37b. Figures 37c and 37d show the MRO comprising the ePTFE microporous polymer reinforcement. This MRO has a more uniform appearance, lacking the conspicuous hierarchical pore structure of Example 32. These three Inventive Examples were compared to Example 34, a state-of-the-art separator for Liquid Alkaline Water Electrolysis, the Zirfon® UTP 500 porous diaphragm available from AGFA.

[0271] Liquid permeance was evaluated using the high-pressure flow cell shown in Figure 29a. A cross-section of this flow cell is shown in Figure 38. The liquid permeance values of Example 32 (comprising expanded functional copolymer), Example 31 (comprising ePTFE), and Example 34 (comparative) are shown in Figure 32, in which liquid permeance (in this case, permeance to isopropyl alcohol or IPA) is shown on a logarithmic scale. The MRO separators had approximately 2 orders of magnitude lower liquid permeance than the comparative example. Such a dramatically lower level of liquid permeance than the state-of-the-art porous diaphragm is expected to significantly reduce the exchange of electrolyteP390218USP 3252US01between the anode side and cathode side of the electrolyzer during potential pressure upsets, reducing H2crossover as a result.

[0272] Shorting protection for LA WE was evaluated using the test setup shown in Figure 40 using the corresponding method described herein. As can be seen from Table 4, the diaphragms of Examples 31 to 33 have acceptable strength and shorting protection properties to function effectively in liquid alkaline water electrolysis.

[0273] Polarization curves were measured in a small (10 cm2) zero-gap liquid alkaline water electrolyzer as described herein using Electrocel hardware, 30 wt% KOH aqueous electrolyte, and nickel felt electrodes. During assembly of the electrochemical cells, care was taken to ensure thorough wetting of the porous diaphragms with the aqueous electrolyte to enable integration of the electrolyte with the separator, in this case liquid electrolyte disposed in the pores of the MRO, to enable efficient ion conduction across the separator. Polarization curves for Example 34 (comparative), Example 32 (MRO separator comprising porous PE), and Example 32 (MRO separator comprising expanded functional copolymer) are shown in Figure 41a. The polarization curves of the Inventive Examples comprising MROs are significantly better than the Comparative Example. To better isolate the performance of the porous diaphragms, the ionic resistance (expressed in mW*cm2) associated with each separator was estimated by determining the slopes of the descending polarization curves using the data from 500 mA / cm2to 1000 mA / cm2and subtracting the estimated system resistance of 219 mW*cm2. The resulting values of ionic resistance are shown in Figure 41b.As shown in the figure, the estimated ionic resistances of the Inventive Examples comprising MROs were significantly better than the Comparative Example. The best performance (i.e., best polarization curve and lowest ionic resistance) was observed with Example 32 using an MRO comprising an expanded functional copolymer microporous polymer scaffold, and having a hierarchical pore structure. Without wishing to be bound by theory, the improvement in performance observed with Example 32 may be attributed in part to the increased hydrophilicity of the microporous polymer scaffold. Without being bound by theory, it is believed to be important for the microporous polymer scaffold to be hydrophilic (and therefore acceptably non-dewettable) to prevent bubbles from the electrolyte from nucleating on and / or sticking to and therefore “blinding” the diaphragm by de-wetting, thus increasing its ionic resistance. The expanded functional copolymer may be considered to comprise a polymer electrolyte.

[0274] It is particularly promising that the MRO Separators demonstrated both lower ionic resistance and lower liquid permeance than the comparative state-of-the-art porous diaphragm, indicating a dramatic improvement in the “Conductance / Permeance” trade-off. Furthermore, the Inventive Examples showed no signs of needing to be shipped and handled wet, unlike the Comparative Example 34.P390218USP 3252US01

[0275] Conventional diaphragms like Example 34 may comprise a woven fabric as a scaffold. Such woven fabrics may have low surface areas, such as a volume specific surface area of about 0.03 m2SUrface / cc, or an area specific surface area of about 2 m2SUrface m2. Such low surface areas may contribute to such woven fabric scaffolds being relatively easy to wet (e.g., with electrolyte in an electrochemical cell, or with a processing fluid during diaphragm production). The MRO Separators (i.e., MRO-based porous diaphragms) described herein comprised a microporous polymer scaffold with high matrix tensile strength. Such microporous polymer scaffolds may exhibit a high surface area, such as a volume-specific surface area of at least about 0.5 m2surface / cc, and particularly at least about 10 m2SUrface / cc, or an area-specific surface area of at least about 5 m2surface / m2, and particularly at least about 50 m2surface / m2. Microporous polymer scaffolds with higher specific surface areas are typically difficult to wet, or they may de-wet significantly when exposed to bubbles. However, the porous diaphragms described herein may be wetted with liquid electrolyte and the electrolyte may remain integrated with the separator, in this case liquid electrolyte disposed in the pores of the MRO, to enable efficient ion conduction across the separator and thereby enable effective operation in liquid alkaline water electrolyzers. Surprisingly, in liquid alkaline water electrolysis testing, the MRO Separators described herein have surpassed the performance of conventional diaphragms with woven fabric scaffold (as measured by e.g., the polarization curve and the estimated ionic resistance from the polarization curve slope).Integrated Ion Transport Layers

[0276] The “MRO / PEM Multilayer Separators” described above and in Examples 25 and 26 may be considered a subset of a larger set of composite materials comprising an MRO and at least one integrated ion transport layer. An integrated ion transport layer (IITL) is a non-MRO layer of material that is physically joined (e.g., bonded or adhered) to the MRO that is configured to transport ions in the intended application (e.g., some IITLs may require the presence of additional electrolyte, such as a liquid electrolyte, to transport ions). The physical joining of the layers may be accomplished by lamination, by direct coating of the IITL on the MRO, by direct coating of the MRO on the IITL, or by any other such means as will be readily apparent to one of ordinary skill in the art. The simplest case is a single MRO physically joined to a single IITL (i.e., MRO-IITL). However, the number of physically joined MROs and IITLs is not particularly limited, and the layers can be physically joined in any order, for instance: MRO-IITL, MRO-IITL-MRO, IITL-MRO-IITL, The IITL may be a polymer film comprising, for example, cation exchange polymers (CEPs), anion exchange polymers (AEPs), polymers of intrinsic microporosity (PIMs), and ion-solvating polymers (ISPs). TheP390218USP 3252US01IITL may be a porous layer of ceramic particles and / or polymeric fibers. The IITL may be a woven or non-woven web (e.g., comprising woven PPS fibers). The combination of the MRO and the IITL may provide benefits over either layer alone. For example, the MRO may enhance the mechanical durability of the IITL, or vice versa. The IITL may be configured to improve adhesion between the MRO and adjacent layers (e.g., to improve adhesion to electrodes).

[0277]

[0278] IFLs may comprise adhesives (e.g. PVDF).

[0279] The preceding examples demonstrate several methods of integrating an electrolyte with the MROs. All the inventive samples from both the Redox Flow Battery data set and the Liquid Alkaline Water Electrolyzer data set integrated liquid electrolyte into the pores of the MRO. Both highly acidic (for VRFB) and highly alkaline (for LA WE) liquid electrolytes were demonstrated. Examples 25 and 26 demonstrated integration of a polymer electrolyte layer to produce a MRO / PEM multi-layer separator. Example 32 demonstrated the use of a microporous polymer scaffold that comprised a polymer electrolyte. And Examples 31, 32, and 33 comprised yttria stabilized zirconia, which may be considered a conductive ceramic electrolyte in some applications. These configurations for integrating an electrolyte into MROs to enhance their performance as electrochemical separators in electrochemical cells or electrochemical devices should not be construed as limiting, and other configurations may be apparent to one of ordinary skill in the art.Test Methods

[0280] Non-Contact Thickness (e.g., of the Microporous Polymer Scaffold)

[0281] A sample of a microporous polymer scaffold was placed over a flat smooth metal anvil and tensioned to remove wrinkles. The height of microporous polymer structure on anvil was measured and recorded using a non-contact Keyence LS-7010M digital micrometer. Next, the height of the anvil without microporous polymer scaffold was recorded. The thickness of the microporous polymer scaffold was taken as a difference between micrometer readings with and without microporous polymer scaffold being present on the anvil.

[0282] Contact Thickness (e.g., of the Membrane-Reinforced Qpaloid)

[0283] A sample of an MRO was analyzed with a Mitutoyo Litematic handheld micrometer with a measuring force of 0.01 Newtons to determine the contact thickness.P390218USP 3252US01

[0284] Mass per Area (e.q., of the Microporous Polymer Scaffold)

[0285] A microporous polymer scaffold was strained to a point sufficient to eliminate wrinkles, and then a 10 cm2piece was cut out using a die. The 10 cm2piece was weighed on a conventional laboratory balance. The mass-per-area (M / A) was then calculated as the ratio of the measured mass to the known area.

[0286] Bulk Density (e.q., of the Microporous Polymer Scaffold)

[0287] The bulk density of the microporous polymer scaffold was calculated by dividing its mass-per-area by its non-contact thickness.

[0288] Skeletal Density (e.q., of the Microporous Polymer Scaffold)

[0289] The skeletal density is the density of a solid calculated by excluding all open pores and internal void volume. A Micromeritics AccuPyc II 1340 Gas Pycnometer (Micromeritics Instrument Corp., Norcross, GA) using helium gas as the displacement medium was used to analyze the samples. The AccuPyc uses the theory of gas displacement to determine the volume occupied by a given sample. The sample was added to a 3.5 cm3sample cup and sealed in the analysis chamber. The sample was purged 50 times with helium gas at 19.5 psig and the gas expands into another precision internal volume. Once purged, the sample was then analyzed with 15 cycles of fill cycles at 19.5 psig, or until the sample volume equilibrium was detected (0.02% precision). The skeletal density was calculated by dividing the sample mass by the adjusted sample volume. The sample mass was determined by weighing on an analytical balance of + / - 0.1 mg sensitivity.

[0290] Sample Skeletal Density = Sample Mass / Sample Volume

[0291] Sample Volume = Sample Chamber Volume - (Expansion Chamber Volume / ((Gauge Pressure After Fill / Gauge Pressure After Expansion) - 1))

[0292] Porosity (e.q., of the Microporous Polymer Scaffold)

[0293] The porosity of the microporous polymer scaffold was calculated by dividing the difference between skeletal density and bulk density of the membrane by the skeletal density of the membrane per the following formula:

[0294] Porosity = ((Skeletal Density - Bulk Density) / Skeletal Density)*100% [Vol%]P390218USP 3252US01

[0295] Absolute tensile strength (e.q., of the Microporous Polymer Scaffold) [first and second directions]

[0296] The tensile strength was determined in each direction by measuring the maximum tensile load of a sample as described in ASTM D638-5, then dividing the load by the original gauge width of the sample.

[0297] Matrix tensile strength (e.q., of the Microporous Polymer Scaffold) [first and second directions]

[0298] The absolute tensile strength (in units of N / mm or equivalent) was normalized to discount pore volume to determine the matrix tensile strength of the microporous polymer scaffold (in units of MPa or equivalent). The matrix tensile strength was calculated by dividing the absolute tensile strength of the sample by a ratio of its bulk density to the skeletal as shown in the following formula:

[0299] Matrix Tensile Strength = (Absolute Tensile Strength / Non-Contact Thickness) / (Bulk Density / Skeletal Density) [MPa]

[0300] Scanning Electron Microscopy (SEM)

[0301] Samples of neat opaloids and membrane-reinforced opaloids were carefully mounted to SEM stubs using double-sided conductive tape. Cross-sections of membrane-reinforced opaloids were prepared using a Gatan® Ilion2 broad beam ion mill with ion beam accelerating voltages of 0.2-5kV at a milling temperature of -150°C to -160°C. The samples were then coated with a thin (2nm) conductive layer of platinum using a Cressington® 208HR sputter coater. SEM images were then obtained using a Hitachi® SU8000 and SU8230 FESEM at an accelerating voltage of 1-3kV, with working distances of 2-8mm, using upper and lower secondary electron detectors.

[0302] Small-Angle X-ray Scattering (SAXS)

[0303] Small-angle X-ray scattering (SAXS) measurements were performed on a Xenocs Xeuss 2.0 instrument. Samples were probed with Cu K-a radiation (A = 0.154 nm). Typical operating conditions were 50kV and 0.6 mA. Sample-to-detector distances ranged from approximately 1200 to 6400 mm. Samples were held under vacuum during scattering experiments, which were performed directly on MROs and neat opaloids. The collection time varied based on the sample-to-detector distance, sample thickness, and operating voltage. Data were calibrated using a silver behenate standard. SAXS data were collected on a 2-D detector, and the intensity distribution provided information about structural length scales and anisotropy. For isotropic structures, the intensity was uniform over 360° (azimuthalP390218USP 3252US01angle) and could be integrated over 360° to obtain 1-D SAXS profiles. MROs and neat opaloids exhibited isotropic 2-D SAXS patterns. The scattering vector or peak position (i.e., the local maximum associated with the structure factor peak), q (in units of nm-1), is proportional to the sine of the scattering angle, θ, and inversely proportional to the wavelength, λ, according to the expression: q = 4πsin(θ) / λ. Values of q can be converted to real space correlation distances with the relationship ID = 2π / q. Lorentz-corrected intensities can be calculated by multiplying intensity by q2. Primary inter-particle structural features may be identified by structure factor peaks in the Lorentz-corrected intensity spectra. A peak herein may be defined as in scipy.signal.find_peaks: " finds all local maxima by simple comparison of neighboring values." E.g. a peak data point will have 2 neighboring values of lesser value. Structure factor peaks generally have a prominence of at least 20%, where prominence is the maximum value of the structure factor peak normalized by the minimum Lorentz corrected intensity in the adjacent region corresponding to interparticle distances larger than the detected peak. Structure factor peaks may also have a prominence of at least about 10%, at least about 20%, at least about 30%, at least about 40%, at least about 50%, at least about 75%, at least about 100%, at least about 200%, at least about 300%, at least about 400%, at least about 500%, or at least about 600%. Structure peaks may also be characterized by their full width at half-prominence. Full width at half prominence may be calculated as the width of the peak (i.e., the length of the line that intersects the contours of the peak at a given Lorentz-corrected intensity) at half the prominence. Structure factor peaks may have a full width at half prominence of less than about 100%, or less than about 70%, or less than about 50%, of the structure peak Inter-particle Distance (ID). Inter-particle distances (ID) larger than 100nm, but smaller than 300nm may be evaluated by use of Ultra Small-Angle X-ray Scattering (USAXS).

[0304] N2 Sorption BET Specific Surface Area (SSA) and Pore Size Distributions

[0305] This technique is also known as BET / BJH. N2 sorption was performed on a Quantachrome AutoSorb iQ MP-XR gas sorption instrument with nitrogen as the adsorbate at 77 K. A starting p / po of 1e-5 was used in order to assess the pore structure of the samples down to the IUPAC-designated micropore regime (< 2 nm). Degassing was performed on the AutoSorb iQ using a step heating profile up to 150 °C under vacuum for four hours. Isotherms were collected with either standard resolution (47 adsorption points, 14 desorption points) or high resolution (65 adsorption points, 38 desorption points). High-resolution runs were carried out by utilizing a delta Vmax of 10 cc / g in addition to a larger number of partial pressure targets. The specific surface area was determined from the nitrogen adsorption data using the Brunauer-Emmett-Teller (BET) method. The range of data points used for this analysis was selected using the Rouquerol method according toP390218USP 3252US01ISO 9277:2010, “Determination of the specific surface area of solids by gas adsorption — BET method.” Density functional theory (DFT) was utilized to calculate the pore size distribution over the IUPAC-designated micropore and mesopore regimes (pores < 50 nm). Based on the smallest fitting error for similar MROs in previous work, the kernel chosen for the DFT calculations was “N2 at 77 K on silica (cylinder pores, NLDFT adsorption branch)”. For the data in the Figures, the mode pore size or primary pore size was the pore size (nm) with the highest specific pore volume (cc / g) in the pore size distribution.

[0306] Volume-specific surface area (e.q., of the Microporous Polymer Scaffold)

[0307] The specific surface area of the microporous polymer scaffold was normalized to account for differences in polymer densities by multiplying by the skeletal density of the microporous polymer scaffold:

[0308] Volume-specific surface area (m2surface / cc) = Specific surface area (m2surface / g) * Skeletal density (g / cc)

[0309] Area-normalized true surface area (e.q., of the Microporous Polymer Scaffold)

[0310] The area-normalized true surface area of the microporous polymer scaffold was calculated by multiplying its specific surface area by its mass per area:

[0311] Area-normalized true surface area (m2surface / m2) = Specific surface area (m2surface / g) * Mass per area (g / m2)

[0312] Haze

[0313] Haze values were determined by from visible light transmittance spectra, which were collected using a Jasco V670 UV-Vis spectrophotometer. MRO samples were loaded onto IR cards with adhesive backers. Calibration standards 99AA 02-1113-7774 and 99AA02-1113-7776 were used. The total transmittance, Tt; sample diffusion rate, t; and instrument diffusion rate, T3; are given by the expressionCTS(A)y(A)MA)dA' CT SWyWdA

[0314] where S is the spectral power distribution of the light source, y is the spectral sensitivity of the human perception of brightness (or luminous efficiency function), and T, is the measured transmittance spectrum. For S, CIE standard illuminant D65 was used, which is representative of average daylight. Fory, a 10-degree logarithmic quantal function was used. The diffuse transmittance, Td, is given by Td= Tt— T3Haze is defined as - and corresponds to the ratio of transmitted light scattered at multiple angles (Td) to all transmitted light (T).P390218USP 3252US01

[0315] Capillary flow porometry

[0316] Capillary flow porometry (CFP) measurements were performed using a Quantachrome capillary flow porometer. Adhesive backers (10 mm diameter) were applied to MROs and samples were die cut. Silicone oil (surface tension ( / iv) about 19.75 mN / m) was applied and wet curves were collected over the full pressure range (about 0.25 to 392 psig or about 0.017 to 27 bar). Equivalent pore diameters were determined using the Young-Laplace equation with a contact angle value (6) of 0°. Figure 32 shows the calculated relationship between capillary pressure (DP) and pore diameter (d) for cylindrical pores assuming the Young-Laplace equation with a surface tension of 19.75 mN / m and a contact angle of zero degrees.

[0317] Bubble Point Pressure

[0318] The bubble point pressure is a means to characterize the pore size of a porous support material and may be measured according to a bubble point measurement as further explained below. For a given fluid and pore size of a porous material (such as the microporous polymer scaffolds and composite membranes of the present disclosure) at constant wetting, the pressure required to force an air bubble through the pore is in inverse proportion to the size of the through-pore (hole). The bubble point pressure can provide a measure of the largest pore size according to the Young-Laplace equation:P = 4γlvcosθdwhere P is the pressure required to dewet a liquid from a cylindrical pore, ylvis the liquid surface tension, 9 is the contact angle, and d is the pore diameter.

[0319] The bubble point pressure was measured according to the general teachings of ASTM F316-03 using a Capillary Flow Porometer (Model 3G zh from Quantachrome Instruments). The sample holder comprised a porous metal plate (Part Number: 196450, Anton Paar), 25.4 mm in diameter and a plastic mask (Part Number ABF-300, Professional Plastics), 18mm inner diameter x 24.5 mm outer diameter. The sample was placed in between the metal plate and the plastic mask. The sample was then clamped down and sealed using an O-ring (Part Number: 193798, Anton Paar). The sample was wet with the test fluid (Silicone fluid, 10 cSt, having a surface tension of 19.75 dynes / cm).

[0320] Mean Flow Pore Diameter

[0321] The mean flow pore diameter was measured according to the general teachings of ASTM F316-03 using a Capillary Flow Porometer (Model 3G zh from Quantachrome Instruments). The dry gas flow data were determined by loading the dry sample into theP390218USP 3252US01sample holder, applying gas pressure to the dry sample, and measuring gas flow rate vs. gas pressure. The wet flow data were measured by loading the sample into the sample holder, wetting the sample with test fluid, applying gas pressure to the wet sample, and measuring the gas flow rate vs. gas pressure. The one-half dry flow data was determined by plotting one-half times the dry gas flow data as a function of gas pressure. The mean flow pore diameter was determined by identifying the intersection point of the one-half dry flow data and the wet flow data, and then using the Young-Laplace equation to convert the corresponding gas pressure from the intersection point to a pore diameter value.

[0322] Organic Solvent Nanofiltration Test (OSN)

[0323] Organic solvent nanofiltration experiments were performed according to the following method. Briefly, MRO samples were stacked on top of three layers of nonwoven membrane and loaded into a stir cell. The permeable spacer membranes were chosen to provide mechanical support to the MRO samples while having minimal impact on liquid permeance and solute rejection. Solvent (e.g., ethanol, molar mass = 46.1 g / mol) was flowed through the stir cell, pressurizing the stir cell (up to about 4 bar) to flow solvent at the desired flow rate. Next, a feed solution of rose bengal (RB; molar mass = 973.7 g / mol; ~ 18 g solution; concentration ~ 10 mg / L) was flowed through the stir cell and six 2-gram samples of permeate solution were collected incrementally as the solution was filtered. The masses of collected permeate samples, mRB,P, and remaining unfiltered, concentrated retentate solution were recorded. Samples were diluted (~ 1 mg / L) and characterized by UV-Vis. The intensity of the RB absorbance peak at A ~ 560 nm was converted to concentration (mg / L), CRB, P, dilute, by dividing the measured absorbance by the Beer’s Law coefficient, 0.23347. The incremental RB concentration in the permeate solution, CRB. P, in, was determined from CRB, P, in= CRB, P, dilute(mEtOH+ mRB, P) / mRB, P, where mEtOHis the mass of ethanol added to dilute the given RB sample to a concentration of 1 mg / L. The RB rejection of each sample was determined from 1 - CRB. P, in / CRB,r, where CRB. P is the corresponding RB concentration in the retentate solution that did not permeate through the filter. The percentage RB rejection was averaged over the six samples.

[0324] Force-Displacement-Resistance (FDR) TestA sample was placed between two porous carbon electrodes (Sigracet 39AA Carbon Paper) and loaded on an Instron model 5542, with electrically isolated 14 mm diameter gold-plated cylindrical platens. The sample and electrodes area were oversized compared to the platens and extended beyond the platen to eliminate edge effects on puncture. The sample area was oversized compared to the electrodes area to prevent electrodes from touching and creating an electronic short that does not path through the sample. Electrical resistance across theP390218USP 3252US01membrane is measured by a Keithley 580 Micro-Ohmmeter connected to the top and bottom platens. The top platen was lowered at ambient conditions at a rate of 1 mm / min while compressive mechanical load is applied to the samples and electrical resistance measured across the sample were constantly recorded until 444.8 N (100 Ibf) was applied; where a higher compression pressure may be accessed with alternative instrumentation or smaller platen active area. Membrane puncture is defined as the pressure when electrical resistance drops below 18,000 ohms, representing physical contact of the electrodes or electrode fibers through the sample. Ten replicates were tested for each sample and the average of the ten runs is reported as the average puncture pressure. Puncture pressure is dependent on electrode material and may significantly increase or decrease if alternative electrode materials are used.

[0325] Proton Area Specific Resistance Test (H+ASR)A sample was placed between two porous carbon electrodes (Sigracet 39AA Carbon Paper) and loaded in a Scribner Cell with 5cm2active area Interdigitated Flow Field. The flow fields are standard graphite flow fields with gold backing plates. The system uses 10-mil ePTFE gasket material. Soak the sample to be tested in DI water for at least 1 minute prior to cell assembly. Complete cell assembly by inserting the eight bolts through the end plates and tightening them in a star pattern to 1 Newton-meter using a torque wrench.. 3.25M H2SO4 was pumped through the system with a Masterflex L / S Variable Speed Pump Drive with Masterflex L / S Pump Head at a pump rate of 50 rpm. A Biologic Single Channel Potentiostat was used to measure AC Impedance of the cell. The AC Impedance was run at a frequency range of 500kHz to 10Hz, a voltage amplitude of 10mV, 10 points per decade, 3 measurements per point, and 10 sweeps. The H+resistance (expressed in ohms) was determined from the high-frequency intercept of the data with the real axis (Nyquist plot). The proton (H+) resistance was multiplied by the active area to calculate the H+Area-Specific Resistance (expressed in ohm*cm2).

[0326] Liquid Permeance (e.q. of a porous diaphragm for LA WE)A 50 mm diameter sample was cut and placed inside a METcell 2-inch Crossflow cell from Evonik (parts METXF-2.5-136 and METXF-2.5-137) liquid flow cell shown in Figure 30. A layer of hydrophilic PVDF membrane (part GVWP04700 from Millipore Sigma) was placed in between the sample and the metal frit support to prevent damage to the sample. Isopropyl alcohol was pressurized to between 1-50 bar via a head of pressurized nitrogen and flowed through the sample for 30 minutes. The pressure was selected to provide a reasonable test time for a particular sample. The permeate alcohol was collected at the outlet of the cell in a flask and its mass measured on a conventional laboratory scale to determine the permeanceP390218USP 3252US01of the sample per the following equation: Permeance = Permeate Mass / Permeate Density / ((Sample Diameter / 2)A2*pi) / Flow Time / Pressure

[0327] Shorting Protection (e.g., of a porous diaphragm) for LA WEShorting protection was measured using a Universal Instron® test system with 100 Ibf load cell, an integrated Keithley 580 Micro-Ohmmeter, and 14mm diameter test probes. The Bottom Probe is flat, while the Top Probe is rounded (i.e., approximately hemispherical) as shown in Figure 29. A sample (e.g., a separator or diaphragm sample) was cut to approximately 1x1 inches and placed on the bottom probe. An example electrode, 40x40 stainless steel square mesh with a wire diameter of 0.0065”, available from McMaster-Carr®, was cut to about 0.5x0.5 inches and placed on the top surface of the sample. The Top Probe was lowered at a rate of 0.1 mm per second while the resistance between probes was measured. When the resistance dropped to below overload (200kOhm), the force was recorded as the Force-to-Short.

[0328] Ex-situ Ionic Resistance (e.g., a composite membrane) for LA WEEx-situ ionic resistance was measured using stainless steel disk electrodes, a portable potentiostat, and a conductivity standard. A 40 mm porous diaphragm sample was punched with a die, wet with isopropyl alcohol, and placed into a jar with 10000 pS conductivity standard (Fisher Scientific 15-077-952) for at least 1 hour. The sample was then placed on the 50 mm bottom disk electrode, which has a 5 mm lip to hold a small pool of solution. After 1 mL of additional solution was added on the porous diaphragm, the 20 mm diameter top electrode, wrapped in about 5 mm thick PTFE was placed on top, with an approximately 1 kg hollow cylindrical weight to hold the electrode in place. Leads from a portable potentiostat (PalmSens Sensit BT) were attached to the top and bottom electrode. Using PSTrace software, an Impedance Spectroscopy measurement was taken from 15 kHz to 150 kHz. In JMP®Pro 16.1.0, a line was fit to the Zreaiand -Zimagto estimate the Zreaiintercept, which was recorded as the ex-situ ionic resistance.

[0329] Polarization curve slope of the LA WE porous diaphragmPolarization curve slopes were measured on a 10 cm2porous diaphragm sample using Electrocell hardware. A zero-gap arrangement was achieved with a series of EPDM and PTFE gaskets and spacers. Nickel felt (Baekert) was used as both the anode and cathode and nickel foam was used as a compressible porous transport layer. The resultant cell was operated at atmospheric pressure, at 80 °C, and with a 30 wt% aqueous KOH electrolyte. The cell was preconditioned for two minutes each at applied current densities of 50, 300, 600, 1000, 600,P390218USP 3252US01300, 50 mA / cm2for a total of 5 cycles, then 15 minutes at 50 mA / cm2and 15 minutes at 600 mA / cm2.Two polarization curves were generated by applying current density setpoints of 5, 10, 20, 30, 40, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000 mA / cm2for two minutes each in ascending, then descending order. Polarization curves were generated using the average voltage over the last 30 seconds at each current density. Polarization curve slopes were generated using a fit line on the region from 500-1000 mA / cm2of the descending polarization curves.

[0330] Alkaline stability of the LA WE porous diaphragmA diaphragm sample was submerged in a lidded beaker containing 500 mL of 30 wt% aqueous potassium hydroxide and heated on a hot plate to 80°C under stirring. The sample was conditioned in this setup for a time relevant to the application, then removed, rinsed 4 times in RO water, dried, and evaluated for properties relevant to the application. Examples of relevant times may include 24 hours, 1 week, 1 month, up to 3 months, up to 6 months, and up to 1 year. These relevant times are in general shorter than the expected lifetime of the porous diaphragm in use and are intended to provide directional feedback to inform, for example, the development, qualification, and quality control of materials. A porous diaphragm for liquid alkaline water electrolysis may be expected to last 5-10 years in operation.Examples

[0331] Comparative Example 1 - Neat (i.e., non-reinforced) opaloid comprising SiO2sub-micron particles with diameter of about 7 nm

[0332] Approximately 10g of an aqueous colloidal dispersion of nominally 7 nm diameter silica particles (Ludox® SM-AS, W. R. Grace) was poured into a small glass petri dish such that the bottom of the petri dish was covered with the colloidal dispersion. The dish was left open to dry inside a fume hood for 2-3 days until all the water had evaporated, leaving the dried silica in the dish. The result was a neat (non-reinforced) opaloid as shown in Figure 2.SAXS data for this neat opaloid is shown in Figure 5, and specific surface area data is shown in Figure 9.

[0333] Comparative Example 2 - Neat (i.e., non-reinforced) opaloid comprising SiO2 sub-micron particles with diameter of about 12 nm

[0334] Approximately 10g of an aqueous colloidal dispersion of nominally 12 nm diameter silica particles (Ludox® AS-30, W. R. Grace) was poured into a small glass petri dish such that the bottom of the petri dish was covered with the colloidal dispersion. The dish was leftP390218USP 3252US01open to dry inside a fume hood for 2-3 days until all the water had evaporated, leaving the dried silica in the dish. The result was a neat (non-reinforced) opaloid as shown in Figure 1a.SAXS data for this neat opaloid is shown in Figure 5 and Figure 15. The pore size distribution of this opaloid is shown in Figure 6, Figure 16, and Figure 17. Specific surface area data for this opaloid is shown in Figure 9.

[0335] Comparative Example 3 - Neat (i.e., non-reinforced) opaloid comprising SiO2sub-micron particles with diameter of about 22 nm

[0336] Approximately 10g of an aqueous colloidal dispersion of nominally 22 nm diameter silica particles (Part Snowtex® ST-50, Nissan Chemical) was poured into a small glass petri dish such that the bottom of the petri dish was covered with the colloidal dispersion. The dish was left open to dry inside a fume hood for 2-3 days until all the water had evaporated, leaving the silica in the dish. The result was a neat (non-reinforced) opaloid as shown in Figure 1b. The SAXS data for this neat opaloid is shown in Figure 5, along with the specific surface area data shown in Figure 9.

[0337] Comparative Example 4 - Neat (i.e., non-reinforced) opaloid comprising SiO2 sub-micron particles with diameter of about 45 nm

[0338] Approximately 10g of an aqueous colloidal dispersion of nominally 45 nm diameter silica particles (Snowtex® ST-30LH, Nissan Chemical) was poured into a small glass petri dish such that the bottom of the petri dish was covered with the colloidal dispersion. The dish was left open to dry inside a fume hood for 2-3 days until all the water had evaporated, leaving the dried silica in the dish. The result was a neat (non-reinforced) opaloid. SAXS data for this neat opaloid is shown in Figure 5, and specific surface area data is shown in Figure 9.

[0339] Comparative Example 5 - Neat (i.e., non-reinforced) opaloid comprising SiO2 sub-micron particles with diameter of about 100 nm

[0340] Approximately 10g of an aqueous colloidal dispersion of nominally 100 nm diameter silica particles (Part Snowtex® MP-1040-H, Nissan Chemical) was poured into a small glass petri dish such that the bottom of the petri dish was covered with the colloidal dispersion. The dish was left open to dry inside a fume hood for 2-3 days until all the water had evaporated, leaving the dried silica in the dish. The result was a neat (non-reinforced) opaloid as shown in Figure 1c and Figure 4. SAXS data for this neat opaloid is shown in Figure 5, and specific surface area data is shown in Figure 9.

[0341] Example 6 - Membrane-Reinforced Opaloid comprising ePTFE microporous polymer scaffold with 1.9 bar bubble point and SiO2 sub-micron particles with diameter of about 12 nm

[0342] An ePTFE microporous polymer scaffold known in the art was processed by methods known to those skilled in the art following the teaching of U. S. Patent 8,158,235 to Gore with these modifications: 1) Blending PTFE fine powder (PTFE 601A, DuPont,P390218USP 3252US01Wilmington, DE) with a lubricant (Isopar K, Exxon, Houston, TX) in the proportion of 120 cc / lb.2) Compressing the lubricated powder into a cylindrical shape. 3) Paste extruding at a reduction ratio of 126:1. 4) Calendering to a thickness of 0.008 inch. 5) Drying the tape in a convention oven setto 210C. 6) Longitudinally stretching the tape between two banks of rollers separated by a 344C heat zone at a ratio of 4.75:1 with a rate of 31% / sec. 7) Transversely stretching the longitudinally stretched tape in a 350C heat zone, while constraining the tape from shrinking in the longitudinal direction at a ratio of 21.4:1 with a rate of 76% / sec. 8) Subjecting the stretched tape to a 380C heat zone while constrained. The ePTFE microporous polymer scaffold (with attributes of scaffold A as shown in Table 1a and Table 1b) was restrained in a 6-inch diameter metal hoop and tensioned by hand to remove wrinkles, resulting in a scaffold restrained in the 6-inch hoop. An imbibing fluid was prepared by combining a silica nanoparticle colloidal dispersion (Ludox® AS-30, W. R. Grace) with an aqueous wetting package as follows. 1 g of Ludox® AS-30, 0.02 g Lonza Barlox 8S, and 0.02 g 1 -hexanol were combined in a small sample vial and then shaken vigorously to emulsify the 1-hexanol. The nanoparticles were nominally 12 nanometers in diameter and the as-received colloidal dispersion was 30 mass% in water. The mixture was pipetted onto the surface of the scaffold and spread evenly using the side of a plastic rod until it fully wet the ePTFE (about 30 seconds). Excess imbibing fluid was removed by wiping the surface of the ePTFE scaffold with a Kimwipe® tissue. The sample was dried with a heat gun at 200°F (93.3°C) until visibly dry and heated in a standard convection oven at 250°C for 1 hour to remove residual processing fluids and residual aqueous wetting package. The result was the membrane-reinforced opaloid as shown in Figure 12 and Figure 13. The pore size distribution of this MRO is shown in Figure 16 and Figure 17. The sample is optically hazy as shown in Figure 24. In Figure 25, the capillary flow porometry data shows the bubble point of the MRO. The performance of the MRO in an organic solvent nanofiltration test is shown in Figure 27.

[0343] Example 7 - Membrane-Reinforced Opaloid comprising ePTFE microporous polymer scaffold with 7.6 bar bubble point and mass-per-area of about 2 g / m2, and SiO2 sub-micron particles with diameter of about 12 nm

[0344] An ePTFE microporous polymer scaffold known in the art was processed by methods known to those skilled in the art following the teaching of U. S. Patent 7,306,729 to Gore. The ePTFE microporous polymer scaffold (with attributes of scaffold C as shown in Table 1a and Table 1b) was restrained in a 6-inch metal hoop and tensioned by hand to remove wrinkles, resulting in a scaffold restrained in the 6-inch hoop. A second ePTFE scaffold (with attributes of scaffold A as shown in Table 1a and Table 1b) was restrained in an 8-inch diameter plastic hoop, resulting in a scaffold restrained in the 8-inch hoop. The scaffold restrained in the 8-inch hoop was placed on top of the scaffold restrained in the 6 inch hoop such that the scaffolds were in contact. An imbibing fluid was prepared byP390218USP 3252US01combining a silica nanoparticle colloidal dispersion (Ludox® AS-30, W. R. Grace) with an aqueous wetting package as follows. 1 g of Ludox® AS-30, 0.02 g Lonza Barlox 8S, and 0.02 g 1 -hexanol were combined in a small sample vial and then shaken vigorously to emulsify the 1-hexanol. The nanoparticles were nominally 12 nanometers in diameter and the as-received colloidal dispersion was 30 mass% in water. The mixture was pipetted onto the surface of the top ePTFE microporous polymer scaffold (scaffold A, the one restrained in the 8” hoop) and spread evenly using the side of a plastic rod until it fully wet both ePTFE layers (about 30 seconds). The scaffold restrained on the 8-inch plastic hoop was removed and discarded (resulting in the removal of excess imbibing fluid). The sample (i.e., the wetted ePTFE scaffold in the 6-inch hoop, with attributes of scaffold C) was dried with a heat gun at 200°F (93.3°C) until visibly dry and heated in a standard convection oven at 250°C for 1 hour to remove residual processing fluids and resid...

Claims

P390218USP 3252US01CLAIMS:

1. A system comprising:an electrolyte; anda composite membrane; wherein the composite membrane comprises:a microporous polymer scaffold having a scaffold matrix and a plurality of scaffold pores having a scaffold pore volume, anda colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles,wherein the three-dimensional packing arrangement of sub-micron particles exhibits at least one structure factor peak in Lorentz-corrected SAXS data.

2. The system of claim 1, wherein the submicron particles comprise core-shell particles comprising the submicron particles coated with a shell.

3. The system of claim 2, wherein the submicron particles comprise submicron ceramic particles4. The system of claim 2 wherein the shell comprises aluminum; optionally wherein the shell comprises AI2O3, boehmite (AIO(OH)) or combinations thereof.

5. The system of any preceding claim, wherein the submicron particles have a particle diameter or effective diameter of from about 5 nanometers to about 200 nanometers.

6. The system of any preceding claim, wherein the microporous polymer scaffold comprises a microporous hydrocarbon scaffold and preferably, comprises a microporous polyolefin scaffold.

7. The system of any preceding claim, wherein the microporous hydrocarbon polymer scaffold comprises any one or more polymers selected from polytetrafluoroethylene (PTFE), polyethylene (PE), polypropylene (PP), or combinations thereof.

8. The system of any preceding claim, wherein a largest pore of the plurality of scaffold pores, has a pore diameter, as determined by bubble point, which is from about 3 to about 15 times the particle diameter or effective particle diameter of the submicron ceramic particles.P390218USP 3252US019. The system of any preceding claim, wherein the plurality of scaffold pores have a scaffold pore diameter which from about 1 to about 15 times of a particle diameter or effective particle diameter of the submicron ceramic particles.

10. The system of any preceding claim, wherein the inter-particle pores between the submicron ceramic particles are defined by an inter-particle distance within the three-dimensional packing arrangement of sub-micron ceramic particles, and wherein the interparticle distance is from about 0.5 times to about 3 times the particle diameter or effective particle diameter of the submicron ceramic particles.

11. The system of any preceding claim, wherein the continuous ceramic phase disposed within the scaffold pore volume has a ratio (d / D) of an inter- particle pore size, d, to particle diameter or effective diameter, D, of from about 0.2 to about 1.2.

12. The system of any preceding claim, wherein a packing density of the ceramic particles is from about 0.40 to about 0.85.

13. The system of any preceding claim, wherein the porosity of composite membrane is from about 30% to about 70%.

14. The system of any preceding claim, wherein the volume ratio of sub-micron ceramic particles to scaffold matrix in the composite membrane is from about 0.5 to about 3.

15. The system of any preceding claim, wherein the colloidal condensed phase extends substantially through the entire thickness of the scaffold.

16. The system of any preceding claim, wherein the contact thickness of the composite membrane is from about 1 micron to about 150 microns.

17. The system of claim 1, wherein the electrolyte is arranged, in use, to permit the transport of ions across the composite membrane.

18. The system of any preceding claim, wherein the composite membrane comprises a total membrane thickness and the electrolyte is within the total membrane thickness.

19. The system of any preceding claim wherein the electrolyte is incorporated at least partially within the composite membrane pores.P390218USP 3252US0120. The system of any preceding claim, wherein microporous polymer scaffold comprises a polymer electrolyte.

21. The system of any preceding claim, wherein the electrolyte is incorporated within the colloidal condensed phase.

22. The system of any preceding claim, wherein the composite membrane comprises a plurality of composite layers, and wherein at least one of the composite membrane layers comprises a polymer electrolyte membrane layer.

23. The system of claim 22, wherein the polymer electrolyte membrane layer is arranged adjacent to the microporous polymer scaffold.

24. The system of any preceding claim, wherein the electrolyte comprises a liquid electrolyte.

25. The system of claim 24, wherein the electrolyte comprises at least one of a liquid alkaline electrolyte or a liquid acidic electrolyte.

26. The system of any preceding claim, wherein the microporous polymer scaffold has a bubble point pressure equal to or greater than 1 bar.

27. The system of claim 26, wherein the microporous polymer scaffold has a bubble point pressure equal to or greater than 1.9 bar.

28. The system of any preceding claim, wherein the composite membrane comprises a bubble point of equal to or greater than 10 bar.

29. The system of any preceding claim, wherein the colloidal condensed phase comprises a three- dimensional packing arrangement of sub-micron particles, and wherein the composite membrane pores are defined at least in part by an inter-particle distance within the packing arrangement.

30. The system of claim 29, wherein the inter-particle distance is from about 0.5 times to about 3 times the sub-micron diameter or effective diameter.

31. The system of any preceding claim, wherein the sub-micron particles have a submicron particle diameter or effective diameter, and the composite membrane pores have a composite membrane pore size, and wherein the mode composite membrane pore size is within 0.15 to 2 times the sub-micron particle diameter or effective diameter.

32. The system of any preceding claim, wherein the porosity of the composite membrane is between about 10 to 75%.

33. The system of any preceding claim, wherein the colloidal condensed phase comprises an inter- particle pore size of about 0.15 to about 1.5 times the sub-micron particle diameter or equivalent diameter.

34. The system of any preceding claim, wherein the sub-micron particles have a diameter or an equivalent diameter of from 1 nm to 100 nm.

35. The system of any preceding claim, wherein the sub-micron particles comprise at least one of ceramics or glasses.P390218USP 3252US0136. The system of claim 35 wherein the at least one of ceramics or glasses is selected from: silicon dioxide, aluminium oxide, titanium dioxide, cerium oxide, zirconium dioxide, yttria-stabilized zirconium dioxide, other oxides, and other classes of ceramics including carbides, nitrides, sulfides, borides, phosphides, selenides, titanates, carbonates, nitrates, sulfates, borates, and phosphates, or combinations thereof.

37. The system of any preceding claim, wherein the sub-micron particles may comprise at least two different populations of sub-micron particles, wherein a first population of sub-micron particles has a first particle diameter (or effective particle diameter) and a second population of sub-micron particles has a second particle diameter (or effective diameter).

38. The system of any preceding claim, wherein the composite membrane comprises a plurality of microporous polymer scaffolds.

39. The system of any preceding claim, wherein the plurality of scaffold pores are at least partially filled with the colloidal condensed phase.

40. The system of claim 39 wherein the colloidal condensed phase extends continuously across at least a portion of the scaffold pores in at least one direction by at least about 1 mm.

41. The system of any preceding claim, wherein the microporous polymer scaffold has a first direction, a second direction and a thickness direction, wherein the first direction is orthogonal to the second direction, and the first and second directions are each orthogonal to the thickness direction, and wherein the microporous polymer scaffold has a matrix tensile strength (MTS) in the second direction of at least about 55 MPa, wherein the second direction is the direction in which the microporous polymer scaffold has its minimum matrix tensile strength.

42. The system of any preceding claim, wherein the microporous polymer scaffold has a geometric mean MTS of at least about 90 MPa.

43. The system of any preceding claim, wherein the microporous polymer scaffold has a mass-per-area ranging from about 1 g / m2to about 30 g / m2.

44. The system of any preceding claim, wherein the microporous polymer scaffold is selected from one of a non-fluorinated polymer, a partially fluorinated polymer, a perfluorinated polymer, and any combination thereof.

45. The system of any preceding claim, wherein the microporous polymer scaffold comprises polyolefins, optionally, polyethylene (PE) or polypropylene (PP).

46. The system of any preceding claim, wherein the microporous polymer scaffold comprises at least two microporous polymer scaffolds, optionally, wherein a first microporous polymer scaffold comprises a first polymer and the second microporous polymer scaffold comprises a second polymer; optionally, wherein the first microporous polymer scaffold comprises polyethylene (PE) and the second microporous polymer scaffold comprises polypropylene (PP).P390218USP 3252US0147. The system of any preceding claim, wherein the microporous polymer comprises any polymer selected from the following group: a polytetrafluoroethylene (PTFE), a polyethylene (PE), or a copolymer of PTFE and PE, expanded polyethylene (ePE), expanded polytetrafluoroethylene (ePTFE), or combinations thereof.

48. The system of any preceding claim wherein the system additionally comprises an integrated ion transport layer comprising any one or more of the following:- Anion exchange polymers- Ion-solvating polymers- Polymers of intrinsic microporosity- Ceramic particle layer; and- Nano-cellulose or other water-getters or sorbing agents.

49. An electrochemical device comprising: an anode; a cathode; and the system of any of claims 1 to 48.

50. The electrochemical device of claim 49, wherein the electrolyte is positioned between the anode and the cathode to permit, in use, the transport of ions between the cathode and the anode.

51. The electrochemical device of claim 49 or 50 wherein the anode comprises any one selected from nickel, cobalt, and iron.

52. The electrochemical device of any of claims 49 to 50, wherein the cathode comprises any one selected from nickel, platinum, and carbon.

53. The electrochemical device according to any of claims 49 to 52, wherein the electrochemical device is one of: an electrolyzer, a redox flow battery, a fuel cell, or a rechargeable battery.54 Use of the system as defined in any of claims 1-48 or the electrochemical device as defined in any of claims 48-52 in the electrolysis of water to produce hydrogen.

55. Use of the system as defined in any of claims 1-48, or the electrochemical device as defined in any of claims 48-52 in one of: an electrolyzer or a redox flow battery.

56. A method of manufacturing the system according to claims 1 -48, or the electrochemical device according to claims 49-53, wherein the method comprises:a) obtaining a polymer scaffold, wherein the microporous polymer scaffold has a polymer scaffold matrix and a plurality of scaffold pores, the microporous polymer scaffold having a scaffold pore volume and having a porosity from about 70% to about 96%;(b) incorporating sub-micron particles into the scaffold pore volume of the microporous polymer scaffold; and(c) consolidating the sub-micron particles such that they form a colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;P390218USP 3252US01wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles; andwherein the three-dimensional packing arrangement of sub-micron particles exhibits at least one structure factor peak in Lorentz-corrected SAXS data.

57. The method of claim 56 or 57, wherein the microporous polymer scaffold has a porosity of at least about 75%.

58. The method of claim 56 or 57, wherein the submicron particles comprise submicron ceramic particles.

59. The method of any of claims 56 to58 wherein the microporous polymer scaffold comprises a microporous hydrocarbon polymer scaffold.

60. The method of any of claims 56 to 59 wherein the scaffold has a strength in the Machine Direction (MD) of from about 0.3 N / mm to about 2.0 N / mm.

61. The method of any of claims 56 to 60, wherein the microporous polymer scaffold has a mass-per-area of between 0.5 g / m2and 3 g / m2.

62. The method of any of claims 56 to 61, wherein the microporous polymer scaffold has a bubble point of about 10 bar.

63. The method of any of claims 56 to 62, wherein (a) further comprises:obtaining a microporous polymer scaffold, wherein the microporous polymer scaffold comprises a plurality of scaffold pores, each of said scaffold pores having a scaffold pore volume;incorporating sub-micron particles into the scaffold pore volume of the plurality of pores of the microporous polymer scaffold within the scaffold pores and forming a colloidal condensed phase within the scaffold pore volume.

64. The method according to any of claims 56 to 63, wherein (b) further comprises at least one of:incorporating the electrolyte at least partially into the composite membrane pores; forming the microporous polymer scaffold from a polymer electrolyte; incorporating the electrolyte into the colloidal condensed phase;arranging a polymer electrolyte membrane layer adjacent to the microporous polymer scaffold.

64. A supported liquid membrane comprising:a composite membrane wherein the composite membrane comprises:a microporous polymer scaffold having a scaffold matrix and a plurality of scaffold pores having a scaffold pore volume, andP390218USP 3252US01a colloidal condensed phase disposed within the scaffold pore volume, wherein the colloidal condensed phase extends within the scaffold pore volume a distance of at least 1 mm in each of two orthogonal directions;wherein the colloidal condensed phase comprises a three-dimensional packing arrangement of sub-micron particles,wherein the three-dimensional packing arrangement of sub-micron particles exhibit at least one structure factor peak in Lorentz-corrected SAXS data.

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