Resilient silica aerogels with reduced processing

Abstract

Described herein is a method of preparing a wet gel material comprising: providing a precursor solution comprising silica gel precursor materials and a solvent, wherein the silica gel precursor materials comprise more than about 36 wt.% of at least one hydrophobic inorganic precursor material; and allowing the silica gel precursor materials in the precursor solution to transition into a wet gel material, wherein the wet gel material comprises a silica-based framework and the solvent.

Description

AAI-100-B-PCT (1197-WOOl)RESILIENT SILICA AEROGELS WITH REDUCED PROCESSINGCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U. S. Provisional Application No. 63 / 555,776, filed February 20, 2024, which is incorporated by reference herein in its entirety.TECHNICAL FIELD

[0002] The invention relates generally to aerogel technology. The invention relates more particularly to improved methods for producing aerogels and improved aerogel materials and composites.BACKGROUND

[0003] Low-density aerogel materials are widely considered to be the best solid insulators available. Aerogels function as insulators primarily by minimizing conduction (low structural density results in tortuous path for energy transfer through the solid framework), convection (large pore volumes and very small pore sizes result in minimal convection), and radiation (IR absorbing or scattering dopants are readily dispersed throughout the aerogel matrix). Aerogels can be used in a broad range of applications, including heating and cooling insulation, acoustics insulation, electronic dielectrics, aerospace, energy storage and production, and filtration. Furthermore, aerogel materials display many other interesting acoustic, optical, mechanical, and chemical properties that make them abundantly useful in various insulation and non-insulation applications.

[0004] Large-scale production of aerogel materials or compositions can be complicated by difficulties related to the continuous formation of gel materials on a large scale; as well as the difficulties related to liquid phase extraction from gel materials in large volumes. It is desirable to develop efficient techniques for the large-scale production of aerogel materials.AAI-100-B-PCT (1197-WOOl)SUMMARY

[0005] It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previous methods and materials mentioned above. The methods and systems described herein are designed to improve the process of making aerogel materials and to produce improved aerogels and aerogel composites.

[0006] In a first aspect of the present disclosure, there is provided method of preparing a wet gel material comprising: providing a precursor solution comprising silica gel precursor materials and a solvent, wherein the silica gel precursor materials comprise more than about 36 wt.% of at least one hydrophobic inorganic precursor material; and allowing the silica gel precursor materials in the precursor solution to transition into a wet gel material, wherein the wet gel material comprises a silica-based framework and the solvent.

[0007] The silica gel precursor materials may comprise up to about 90 wt.%, or about 40-80 wt.%, or about 50-70 wt.% of the at least one hydrophobic inorganic precursor material.

[0008] The at least one hydrophobic inorganic precursor material may be selected from the group consisting of trimethyl methoxysilane [TMS], dimethyl dimethoxysilane [DMS], methyl trimethoxysilane [MTMS], trimethyl ethoxysilane, dimethyl diethoxysilane [DMDES], methyl triethoxysilane [MTES], ethyl triethoxysilane [ETES], diethyl diethoxysilane, ethyl triethoxysilane, propyl trimethoxysilane, propyl tri ethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane [PhTES], hexamethyldisilazane and hexaethyldisilazane, and combinations thereof.

[0009] The silica gel precursor materials may further comprise at least one inorganic precursor material selected from: metal silicates such as sodium silicate or potassium silicate; alkoxysilanes such as tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and tetra-n-propoxysilane; partially hydrolyzed alkoxysilanes such as partially hydrolyzed TEOS and partially hydrolyzed TMOS; condensed polymers of alkoxysilanes such as condensed polymers of TEOS and condensed polymers of TMOS; alkylalkoxy silanes, and combinations thereof.

[0010] The silica gel precursor materials may comprise at least one inorganic precursor material and wherein the ratio of hydrophobic inorganic precursor material to inorganic precursor material is about 50:50 or 70:30 or 90:10.AAI-100-B-PCT (1197-WOOl)

[0011] The hydrophobic inorganic precursor material may comprise or consist of MTES, and the inorganic precursor material may comprise or consist of TEOS.

[0012] The solvent may be water and the step of allowing the silica gel precursor materials in the precursor solution to transition into a wet gel material may comprise combining the silica gel precursor materials in a single vessel in the water and catalysing with an acid to produce a wet gel.

[0013] The acid may be ethanoic (acetic) acid or orthophosphoric acid.

[0014] The acid can have a concentration in the precursor solution of about 5 mM to about 150 mM, or about 20 mM to about 120 mM, or about 50 mM to about 100 mM, or about 45 mM to about 120 mM.

[0015] The molar ratio of hydrophobic inorganic precursor material to acid in the precursor solution may be about 10:1 to 200:1, or about 10:1 to 100:1, or about 20:1 to 50:1, or 10:1 to 50:1.

[0016] The solvent can be present in an amount of 10-30 %, 15-25 % or 18-22 % by volume of the precursor solution, preferably wherein the solvent is water.

[0017] The method may further comprise: placing the wet gel material in a vessel; introducing an aging fluid into the vessel; aging the wet gel material by heating the wet gel material and the aging fluid at an aging temperature and an aging pressure.

[0018] The aging temperature may be below the normal boiling point of the aging fluid at atmospheric pressure.

[0019] The aging temperature may be below the boiling point of the aging fluid at the aging pressure and the aging pressure may be greater than atmospheric pressure.

[0020] The aging fluid may comprise, consist of or consist essentially of ethanol or methanol.

[0021] The aging pressure of the vessel may be maintained without the application of external pressure.

[0022] The vessel may contain a headspace, and the aging pressure is provided by compressing gas present in the headspace.

[0023] The aging pressure may be provided by compressing by introducing aging fluid into the closed vessel.

[0024] The wet gel material and aging fluid may be heated to an aging temperature of between about 80 C and about 130 C during aging of the wet gel material.AAI-100-B-PCT (1197-WOOl)

[0025] The wet gel material and aging fluid may be heated to an aging temperature of between about 95 °C and about 120 °C, or about 100 °C and about 115 °C, or about 110 °C, or about 90 to 100 °C and preferably about 95 °C during aging of the wet gel material.

[0026] The wet gel material may be aged for a time between about 1 hour and about 24 hours, optionally wherein the wet gel material is aged for a time between about 2 hours and about 15 hours or 5 hours and 22 hours, or between about 10 hours and 20 hours, and preferably about 16 hours.

[0027] The wet gel material may be aged for a time which comprises a heating up from ambient temperature time, an active aging time and a cooling down to ambient temperature time, wherein the active aging time is from about 30 minutes to about 4 hours, preferably about 1 to about 2 hours, and optionally about 1 hour, and optionally wherein the heating up and cooling down times are up to one hour, preferably about 30 minutes.

[0028] The wet gel material may be aged for a time determined from the aging temperature and the normal severity factor.

[0029] During aging of the wet gel material, aging fluid may be removed, and aging fluid may be introduced substantially continuously.

[0030] The method may further comprise washing the wet gel material with the aging fluid prior to heating the wet gel material, wherein the aging fluid removes and replaces at least a portion of a liquid present in the wet gel material.

[0031] The the wet gel material may comprise a reinforcement material.

[0032] The reinforcement material may be in the form of a continuous sheet.

[0033] No hydrophobizing agent may be added to the wet gel material.

[0034] The method may further comprise extracting a liquid phase from the wet gel material, preferably using supercritical carbon dioxide, and preferably wherein the step of extracting a liquid phase takes place in the same vessel as the aging step.

[0035] The method may not further comprise any subsequent heating (annealing) step.

[0036] The method may further comprise a subsequent heating (annealing) step.

[0037] The subsequent heating step may be performed at a temperature of around 300 to 400 °C and preferably around 350 °C in air or at a temperature of 575 to 615 °C in an inert gas such as nitrogen.AAI-100-B-PCT (1197-WOOl)

[0038] The present disclosure also provides an aerogel composition comprising a silica-based aerogel obtainable by the methods herein described.

[0039] The silica-based aerogel may not be surface treated by a hydrophobizing agent.

[0040] The silica-based aerogel may have a thermal conductivity of about 20 mW / M*K or less and preferably about 17 mW / M*K or less.

[0041] The aerogel composition according to this disclosure may comprise a reinforcement material wherein the reinforcement material preferably comprises a fiber reinforcement material or a foam reinforcement material.

[0042] The aerogel composition may have a compression set of less than around 12 %, less than around 10 % or less than around 8 % when held with a compressive strain of around 50% in a test according to ASTM D3574-17 Sect. 42.1.2.

[0043] The aerogel composition may have a compression set of less than around 60 %, less than around 40 % or less than around 30 % when compressed to 60 % of targeted strain reduced to 50% strain and repeated for 50 cycles.

[0044] The aerogel composition may have a silica density of 0.020 to 0.100 g / cc, 0.030 g / cc to 0.090 g / cc, 0.050 to 0.090 g / cc or 0.075 to 0.100 g / cc.

[0045] In a further aspect of the disclosure, there is disclosed a method of treating a wet gel material, comprising: placing the wet gel material in a vessel; introducing an aging fluid into the vessel; aging the wet gel material by heating the wet gel material and the aging fluid at an aging temperature and an aging pressure, wherein the aging temperature is above the normal boiling point of the aging fluid, wherein the pressure of the vessel is maintained at or below the vapor pressure of the aging fluid during heating.

[0046] The wet gel material may be obtained by a method comprising: providing a precursor solution comprising silica gel precursor materials and a solvent; and allowing the silica gel precursor materials in the precursor solution to transition into a wet gel material, wherein the wet gel material comprises a silica-based framework and the solvent.

[0047] The aging fluid may comprise ethanol or methanol.

[0048] The pressure of the vessel may be maintained without the application of external pressure.

[0049] The wet gel material and aging fluid may be heated to an aging temperature of between about 80 C and about 130 C during aging of the wet gel material.AAI-100-B-PCT (1197-WOOl)

[0050] The wet gel material and aging fluid may be heated to an aging temperature of between about 95 C and about 120 C, or about 100 C and about 115 C, or around 110 C and during aging of the wet gel material.

[0051] The wet gel material may be aged for a time between about 1 hour and about 24 hours optionally wherein the wet gel material is aged for a time between about 2 hours and about 15 hours or 5 hours and 22 hours.

[0052] The wet gel material may be aged for a time which comprises a heating up time and an active aging time, wherein the active aging time is from about 30 minutes to about 4 hours, preferably about 1 to about 2 hours, and optionally about 1 hour.

[0053] The wet gel material may be aged for a time determined from the aging temperature and the normal severity factor.

[0054] During aging of the wet gel material, aging fluid may be removed and aging fluid may be introduced substantially continuously.

[0055] The method of the disclosure may further comprise washing the wet gel material with the aging fluid prior to heating the wet gel material, wherein the aging fluid removes and replaces at least a portion of a liquid present in the wet gel material.

[0056] The wet gel material may comprise a reinforcement material.

[0057] The reinforcement material may be in the form of a continuous sheet.

[0058] The aging pressure can be in a range of around 17 psi (117 kPa) to around 100 psi (689 kPa).

[0059] The aging pressure may be from around 20 psi to around 80 psi, or around 40 psi to around 60 psi, or around 45 to around 50 psi.

[0060] In the disclosed methods, preferably no hydrophobizing agent is added to the wet gel material.

[0061] The disclosed methods may further comprise extracting a liquid phase from the wet gel material, preferably using supercritical carbon dioxide.

[0062] The method may not further comprise any subsequent heating step.

[0063] Alternatively, the method may further comprise a subsequent heating step.

[0064] Optionally the subsequent heating step is performed at a temperature of around 300 - 400 and preferably around 350 °C in air or at a temperature of 575 to 615 °C in an inert gas such as nitrogen.AAI-100-B-PCT (1197-WOOl)

[0065] The present disclosure also provides an aerogel composition comprising a silica-based aerogel and obtainable by the disclosed methods.

[0066] The present disclosure also provides an aerogel composition comprising an intrinsically hydrophobic silica-based aerogel having a hydrophobe content of from around 20 wt.% to around 30 wt.%.

[0067] The silica-based aerogel may not be surface treated by a hydrophobizing agent.

[0068] The silica-based aerogel may include hydrophobic-bound silicon, greater than 50% of the hydrophobic-bound silicon bonded to no more than one alkyl group.

[0069] The disclosed aerogel composition may have a heat of combustion of less than 600 cal / g and preferably less than 525 cal / g.

[0070] The aerogel composition may have a water uptake in the range of about 10 wt.% or less, 7 wt.% or less, 5 wt. % or less, 3 wt.% or less, 2 wt.% or less, or about 1 wt.% or less.

[0071] The aerogel composition may have a water uptake in the range of about 7 wt.% or less and a hydrophobe content of around 22 wt.% to 28 wt.%.

[0072] The silica-based aerogel may have a thermal conductivity about 20 mW / M*K or less.

[0073] The disclosed aerogel composition may comprise a reinforcement material wherein the reinforcement material preferably comprises a fiber reinforcement material or a foam reinforcement material.

[0074] The aerogel composition may have a compression set of less than around 12 %, less than around 10 % or less than around 8 % when held with a compressive strain of around 50% in a test according to ASTMD3574-17 Sect. 42.1.2.

[0075] The aerogel composition may have a compression set of less than around 60 %, less than around 40 % or less than around 30 % when compressed to 60 % of targeted strain, reduced to 50% strain, and repeated for 50 cycles in accordance with the methods described herein.

[0076] It should be understood that the foregoing aspects of the disclosure in this SUMMARY section are not isolated features but are applicable to and combinable with the entire disclosure herein, without limitation.AAI-100-B-PCT (1197-WOOl)BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Advantages of the present invention will become apparent to those skilled in the art with the benefit of the following detailed description of embodiments and upon reference to the accompanying drawings in which:FIG. 1 depicts a schematic diagram of a traditional method of processing a continuous roll of an aerogel.FIG. 2 is a bar chart showing compression set for aerogel materials formed from wet gels aged at different temperatures.FIG. 3 is a bar chart showing compression set for aerogel materials formed from wet gels aged at different temperatures and having different hydrophobe contents.FIGS. 4A and 4B are bar charts showing compression set for aerogel materials formed from wet gels aged at different temperatures and with or without an annealing step.FIGS. 5A to 5C are bar charts showing compression set for aerogel materials formed from wet gels annealed at different temperatures.FIGS. 6A to 6C are bar charts showing compression set for aerogel materials formed from wet gels aged and annealed at different temperatures and having different hydrophobe contents.FIG 7A to 7C are bar charts showing compression set for aerogel materials formed from wet gels annealed at different temperatures and having different hydrophobe contents and at different silica densities.FIGS 8A to 8C are bar charts showing compression set for aerogel materials formed from wet gels annealed at different temperatures and having different hydrophobe contents and at different silica densities.FIG 9 is a bar chart showing compression set for aerogel materials formed from wet gels which were aged and annealed at different temperatures and having different hydrophobe contents and at different silica densities.FIG 10A and 10B are SEM images of aerogel composites having standard amounts of hydrophobe (10A) and high amounts of hydrophobe (10B).AAI-100-B-PCT (1197-WOOl)FIGS 11A to 11B show compression set for different aerogel formulations at different aging and annealing temperatures.FIGS. 12A to 12C show compression set after 24 hours for high-hydrophobe aerogels aged at standard conditions, at different annealing temperatures, and for different silica densities.FIGS. 13A to 13C show compression set after 24 hours for high-hydrophobe aerogels aged at high temperature, at different annealing temperatures, and for different silica densities.FIGS. 14A to 14B show compression set after 24 hours for high-hydrophobe aerogels produced with different amounts of water as solvent, aged at standard (14A) and high (14B) temperature, at different annealing temperatures.FIGS. 15A to 15B show compression set after 24 hours for high-hydrophobe aerogels produced with different amounts of acetic acid as hydrolysis catalyst, annealed and with different silica densities.FIG. 16A shows thermal conductivity for different high-hydrophobe aerogels annealed at different temperatures.FIG. 16B shows compression set for different high-hydrophobe aerogels annealed at different temperatures.

[0078] While the invention may be susceptible to various modifications and alternative forms, aspects of the invention are shown by way of example in the drawings and will herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the form disclosed, but to the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.DETAILED DESCRIPTION

[0079] It is to be understood the present invention is not limited to particular devices or methods, which may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used inAAI-100-B-PCT (1197-WOOl)this specification and the appended claims, the singular forms “a”, “an”, and “the” include singular and plural referents unless the content clearly dictates otherwise. Furthermore, the word “may” is used throughout this application in a permissive sense (i.e., having the potential to, being able to), not in a mandatory sense (i.e., must). The term “include”, “comprise” and derivations thereof, mean “including, but not limited to.” The term “coupled” means directly or indirectly connected.

[0080] The present inventors have found that by modifying previous processes preparing wet gel materials, advantageous aerogels and aerogel compositions can be obtained. In particular, wet gel materials may be prepared from silica gel precursor materials including both hydrophobic inorganic precursor materials and inorganic precursor materials. The inventors have found that unexpectedly good mechanical properties can be achieved when increasing the proportion of hydrophobic inorganic precursor materials in the silica gel precursor materials compared with proportions typically used in the art. In particular these new materials show improved compression set, meaning herein the amount of permanent deformation that occurs when a material is compressed to a specific deformation, for a specified time at a set temperature.

[0081] Additionally, previous wet gel aging methods involved heating an aging fluid to a temperature below its normal boiling point to avoid boiling of the fluid and damaging the eventual aerogel structure. Further advances included applying increased pressure as compared with atmospheric pressure so that the aging fluid could be further heated without boiling, i.e. “hot aging”. Hot aging the wet gel materials of the present disclosure leads to further improvements in material properties. Rather than aging wet gels at artificially elevated pressures, the inventors have found that aging above the normal boiling point of an aging fluid but without externally applying pressure leads to improved products. Wet gels aged according to the present processes exhibit improved mechanical properties. Aerogels and aerogel compositions produced by further processing the wet gels have improved hydrophobicity than prior products. They also exhibit improved thermal decomposition and improved thermal conductivity. The inventors believe that the improved process promotes an enhanced condensation degree of hydrolyzed silica oligomers, including both MTES and SB species, resulting in decreased T2 ((SiO)₂Si-(OH)) and Q3 ((SiO)₃-Si-OH) signals (or increased fully condensed species of T3 and Q4 signals) on solid state 29-SiAAI-100-B-PCT (1197-WOOl)NMR. Aerogel compositions according to the present disclosure exhibit improved mechanical and physical properties compared with known products, as described later.

[0082] Aerogels and aerogel materials

[0083] Aerogels are a class of porous materials with open-cells comprising a framework of interconnected structures, with a corresponding network of pores integrated within the framework, and an interstitial phase within the network of pores which is primarily comprised of gases such as air. Aerogels are typically characterized by a low density, a high porosity, a large surface area, and small pore sizes. Aerogels can be distinguished from other porous materials by their physical and structural properties.

[0084] Within the context of the present disclosure, in some examples, the terms “framework” or “framework structure” refer to the network of nanoscopic and / or microscopic structural elements, such as fibrils, struts, and / or colloidal particles that form the solid structure of a gel or an aerogel. The structural elements that make up the framework structures have at least one characteristic dimension (e.g., length, width, diameter) of about 100 angstroms or less. In examples of pyrolyzed or carbonized aerogels, the terms “framework” or “framework structure” may refer to an interconnected network of linear fibrils, nanoparticles, a bicontinuous network (e.g., networks transitioning between a fibrillar and spherical morphology with aspects of both), or combinations thereof. In some examples, the linear fibrils, nanoparticles, or other structural elements may be connected together (at nodes in some examples) to form a framework that defines pores.

[0085] As used herein, the terms “aerogel” and “aerogel material” refer to a solid object, irrespective of shape or size, comprising a framework of interconnected solid structures, with a corresponding network of interconnected pores integrated within the framework, and containing gases such as air as a dispersed interstitial medium. As such, aerogels are open non-fluid colloidal or polymer networks that are expanded throughout their whole volume by a gas and are formed by the removal of all swelling agents from a corresponding wet gel without substantial volume reduction or network compaction. Aerogels are generally characterized by the following physical and structural properties (according to nitrogen porosimetry testing and helium pycnometry) attributable to aerogels: (a) an average pore diameter ranging from about 2 nm to about 100 nm; (b) a porosity of at least 60% or more, and (c) a specific surface area of about 50m2 / g or more,AAI-100-B-PCT (1197-WOOl)such as from about 100 to about 1500 m2 / g by nitrogen sorption analysis. It can be understood that the inclusion of additives, such as a reinforcement material, may decrease porosity and the specific surface area of the resulting aerogel composite. Densification may also decrease porosity of the resulting aerogel composite. Aerogel materials of the present disclosure include any aerogels which satisfy the defining elements set forth in the previous paragraph.

[0086] Aerogels as disclosed herein have a pore size distribution. As used herein, the term '"pore size distribution'" refers to the statistical distribution or relative amount of each pore size within a sample volume of a porous material. A narrower pore size distribution refers to a relatively large proportion of pores at a narrow range of pore sizes. In some embodiments, a narrow pore size distribution may be desirable in e.g., optimizing the number of pores that can surround an electrochemically active species and maximizing use of the available pore volume. Conversely, a broader pore size distribution refers to a relatively small proportion of pores at a narrow range of pore sizes. As such, pore size distribution is typically measured as a function of pore volume and recorded as a unit size of a full width at half max of a predominant peak in a pore size distribution chart. The pore size distribution of a porous material may be determined by methods known in the art, for example including, but not limited to, surface area, skeletal density, and porosimetry, from which pore size distribution can be calculated. Suitable methods for determination of such features include, but are not limited to, measurements of gas adsorption / desorption (e.g., nitrogen), helium pycnometry, mercury porosimetry, and the like. Measurements of pore size distribution reported herein are acquired by nitrogen sorption analysis unless otherwise stated.

[0087] Aerogel materials or compositions of the present disclosure can have a pore size at max peak from distribution of about 150 nm or less, 140 nm or less, 130 nm or less, 120 nm or less, 110 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, 5 nm or less, 2 nm or less, or in a range between any two of these values.

[0088] Aerogels as disclosed herein have a pore volume. As used herein, the term “pore volume” refers to the total volume of pores within a sample of porous material. Pore volume is specifically measured as the volume of void space within the porous material and is typically recorded as cubic centimeters per gram (cm³ / g or cc / g). The pore volume of a porous material may beAAI-100-B-PCT (1197-WOOl)determined by methods known in the art, for example including, but not limited to, surface area and porosity analysis (e g., nitrogen porosimetry, mercury porosimetry, helium pycnometry, and the like). In certain embodiments, polyimide or carbon aerogels of the present disclosure have a relatively large pore volume of about 1 cc / g or more, 1.5 cc / g or more, 2 cc / g or more, 2.5 cc / g or more, 3 cc / g or more, 3.5 cc / g or more, 4 cc / g or more, or in a range between any two of these values. In other embodiments, polyimide or carbon aerogels and xerogels of the present disclosure have a pore volume of about 0.03 cc / g or more, 0.1 cc / g or more, 0.3 cc / g or more, 0.6 cc / g or more, 0.9 cc / g or more, 1.2 cc / g or more, 1.5 cc / g or more, 1.8 cc / g or more, 2.1 cc / g or more, 2.4 cc / g or more, 2.7 cc / g or more, 3.0 cc / g or more, 3.3 cc / g or more, 3.6 cc / g or more, or in a range between any two of these values.

[0089] Within the context of the present disclosure, the term “aerogel composition” refers to any composite material which includes aerogel material as a component of the composite. Examples of aerogel compositions include but are not limited to: fiber-reinforced aerogel composites; aerogel composites which include additive elements such as opacifiers; aerogel-foam composites; aerogel-polymer composites; and composite materials which incorporate aerogel particulates, particles, granules, beads, or powders into a solid or semi-solid material, such as binders, resins, cements, foams, polymers, or similar solid materials. Aerogel compositions are generally obtained after the removal of the solvent from various gel materials disclosed in this invention. Aerogel compositions thus obtained may further be subjected to additional processing or treatment. The various gel materials may also be subjected to additional processing or treatment otherwise known or useful in the art before subjected to solvent removal (or liquid extraction or drying).

[0090] Within the context of the present invention, the term “monolithic” refers to aerogel materials in which a majority (by weight) of the aerogel included in the aerogel material or composition is in the form of a unitary interconnected aerogel nanostructure. Monolithic aerogel materials include aerogel materials which are initially formed to have a unitary interconnected gel or aerogel nanostructure, but which are subsequently cracked, fractured or segmented into non-unitary aerogel nanostructures. Monolithic aerogel materials are differentiated from particulate aerogel materials. The term “particulate aerogel material” refers to aerogel materials in which a majority (by weight) of the aerogel included in the aerogel material is in the form ofAAI-100-B-PCT (1197-WOOl)particulates, particles, granules, beads, or powders, which can be combined or compressed together but which lack an interconnected aerogel nanostructure between individual particles.

[0091] Aerogel compositions of the present disclosure may include reinforced aerogel compositions. Within the context of the present disclosure, the term “reinforced aerogel composition” refers to aerogel compositions which include a reinforcing phase within the aerogel material which is not part of the aerogel framework. The reinforcing phase can be any material which provides increased flexibility, resilience, conformability or structural stability to the aerogel material. Examples of well-known reinforcing materials include but are not limited to: open-cell microporous foam reinforcement materials, closed-cell microporous foam reinforcement materials, open-cell membranes, honeycomb reinforcement materials, polymeric reinforcement materials, and fiber reinforcement materials such as discrete fibers, woven materials, non-woven materials, battings, webs, mats, and felts. Additionally, fiber-based reinforcements may be combined with one or more of the other reinforcing materials and can be oriented continuously throughout or in limited preferred parts of the composition.

[0092] Within the context of the present disclosure, the term “fiber-reinforced aerogel composition” refers to a reinforced aerogel composition which comprises a fiber reinforcement material as a reinforcing phase. Examples of fiber reinforcement materials include, but are not limited to, discrete fibers, woven materials, non-woven materials, battings, webs, mats, felts, or combinations thereof. Fiber reinforcement materials can comprise a range of materials, including, but not limited to: Polyesters, polyolefin terephthalates, poly(ethylene) naphthalate, polycarbonates (examples Rayon, Nylon), cotton, (e.g. lycra manufactured by DuPont), carbon (e.g. graphite), polyacrylonitriles (PAN), oxidized PAN, uncarbonized heat treated PANs (such as those manufactured by SGL carbon), fiberglass based material (like S-glass, 901 glass, 902 glass, 475 glass, E-glass,) silica based fibers like quartz, (e.g. Quartzel manufactured by Saint-Gobain), Q-felt (manufactured by Johns Manville), Saffil (manufactured by Saffil), Durablanket (manufactured by Unifrax) and other silica fibers, Duraback (manufactured by Carborundum), Polyaramid fibers like Kevlar, Nomex, Sontera (all manufactured by DuPont), Conex (manufactured by Taijin), polyolefins like Tyvek (manufactured by DuPont), Dyneema (manufactured by DSM), Spectra (manufactured by Honeywell), other polypropylene fibers like Typar, Xavan (both manufactured by DuPont), fluoropolymers like PTFE with trade names asAAI-100-B-PCT (1197-WOOl)Teflon (manufactured by DuPont), Goretex (manufactured by W. L. GORE), Silicon carbide fibers like Nicalon (manufactured by COI Ceramics), ceramic fibers like Nextel (manufactured by 3M), Acrylic polymers, fibers of wool, silk, hemp, leather, suede, PBO -Zylon fibers (manufactured by Tyobo), Liquid crystal material like Vectan (manufactured by Hoechst), Cambrelle fiber (manufactured by DuPont), Polyurethanes, polyamaides, Wood fibers, Boron, Aluminum, Iron, Stainless Steel fibers and other thermoplastics like PEEK, PES, PEI, PEK, PPS.

[0093] Reinforced aerogel compositions of the present disclosure may comprise aerogel compositions reinforced with open-cell macroporous framework materials. Within the context of the present disclosure, the term “open-cell macroporous framework” or “OCMF” refers to a porous material comprising a framework of interconnected structures of substantially uniform composition, with a corresponding network of interconnected pores integrated within the framework; and which is characterized by an average pore diameter ranging from about 10 pm to about 700 pm Such average pore diameter may be measured by known techniques, including but not limited to, Microscopy with optical analysis. OCMF materials of the present disclosure thus include any open-celled materials that satisfy the defining elements set forth in this paragraph, including compounds that can be otherwise categorized as foams, foam-like materials, macroporous materials, and the like. OCMF materials can be differentiated from materials comprising a framework of interconnected structures that have a void volume within the framework and that do not have a uniform composition, such as collections of fibers and binders having a void volume within the fiber matrix.

[0094] Within the context of the present disclosure, the term “substantially uniform composition” refers to uniformity in the composition of the referred material within 10% tolerance.

[0095] Within the context of the present disclosure, the terms "aerogel blanket" or “aerogel blanket composition” refer to aerogel compositions reinforced with a continuous sheet of reinforcement material. Aerogel blanket compositions can be differentiated from other reinforced aerogel compositions which are reinforced with a non-continuous fiber or foam network, such as separated agglomerates or clumps of fiber materials. Aerogel blanket compositions are particularly useful for applications requiring flexibility, since they are highly conformable andAAI-100-B-PCT (1197-WOOl)can be used like a blanket to cover surfaces of simple or complex geometry, while also retaining the excellent thermal insulation properties of aerogels.

[0096] Within the context of the present disclosure, the term “wet gel” refers to a gel in which the mobile interstitial phase within the network of interconnected pores is primarily comprised of a liquid phase such as a conventional solvent, liquefied gases such as liquid carbon dioxide, or a combination thereof. Aerogels typically require the initial production of a wet gel, followed by innovative processing and extraction to replace the mobile interstitial liquid phase in the gel with air. Examples of wet gels include, but are not limited to: alcogels, hydrogels, ketogels, carbonogels, and any other wet gels known to those in the art.

[0097] Within the context of the present disclosure, the terms “additive” or “additive element” refer to materials which can be added to an aerogel composition before, during, or after the production of the aerogel. Additives can be added to alter or improve desirable properties in an aerogel, or to counteract undesirable properties in an aerogel. Additives are typically added to an aerogel material either prior or during gelation. Examples of additives include, but are not limited to: microfibers, fillers, reinforcing agents, stabilizers, thickeners, elastic compounds, opacifiers, coloring or pigmentation compounds, radiation absorbing compounds, radiation reflecting compounds, corrosion inhibitors, thermally conductive components, phase change materials, pH adjustors, redox adjustors, HCN mitigators, off-gas mitigators, electrically conductive compounds, electrically dielectric compounds, magnetic compounds, radar blocking components, hardeners, anti -shrinking agents, and other aerogel additives known to those in the art. Other examples of additives include smoke suppressants and fire suppressants. Published U. S. Pat. App. 2007 / 0272902 Al (Paragraphs

[0008] and

[0010] -

[0039] ) includes teachings of smoke suppressants and fire suppressants, and is hereby incorporated by reference according to the individually cited paragraphs.

[0098] Within the context of the present disclosure, the terms “flexible” and “flexibility” refer to the ability of an aerogel material or composition to be bent or flexed without macrostructural failure. Preferably, aerogel compositions of the present disclosure are capable of bending at least 5°, at least 25°, at least 45°, at least 65°, or at least 85° without macroscopic failure; and / or have a bending radius of less than 4 feet, less than 2 feet, less than 1 foot, less than 6 inches, less than 3 inches, less than 2 inches, less than 1 inch, or less than ¼ inch without macroscopic failure.AAI-100-B-PCT (1197-WOOl)Likewise, the terms “highly flexible” or “high flexibility” refer to aerogel materials or compositions capable of bending to at least 90° and / or have a bending radius of less than ½ inch without macroscopic failure. Furthermore, the terms “classified flexible” and “classified as flexible” refer to aerogel materials or compositions which can be classified as flexible according to ASTM classification standard Cl 101 (ASTM International, West Conshohocken, PA).

[0099] Aerogel materials or compositions of the present disclosure can be flexible, highly flexible, and / or classified flexible. Aerogel materials or compositions of the present disclosure can also be drapable. Within the context of the present disclosure, the terms “drapable” and “drapability” refer to the ability of an aerogel material or composition to be bent or flexed to 90° or more with a radius of curvature of about 4 inches or less, without macroscopic failure. An aerogel material or composition of the present disclosure is preferably flexible such that the composition is non-rigid and may be applied and conformed to three-dimensional surfaces or objects, or pre-formed into a variety of shapes and configurations to simplify installation or application.

[0100] Within the context of the present disclosure, the terms “resilient” and “resilience” refer to the ability of an aerogel material or composition to at least partially return to an original form or dimension following deformation through compression, flexing, or bending. Resilience may be complete or partial, and it may be expressed in terms of percentage return. An aerogel material or composition of the present disclosure preferably has a resilience of more than 25%, more than 50%, more than 60%, more than 70%, more than 75%, more than 80%, more than 85%, more than 90%, or more than 95% return to an original form or dimension following a deformation. Likewise, the terms “classified resilient” and “classified as resilient” refer to aerogel materials or compositions of the present disclosure which can be classified as resilient flexible according to ASTM classification standard Cl 101 (ASTM International, West Conshohocken, PA).

[0101] Within the context of the present disclosure, the term “self-supporting” refers to the ability of an aerogel material or composition to be flexible and / or resilient based primarily on the physical properties of the aerogel and any reinforcing phase in the aerogel composition. Self-supporting aerogel materials or compositions of the present disclosure can be differentiatedAAI-100-B-PCT (1197-WOOl)from other aerogel materials, such as coatings, which rely on an underlying substrate to provide flexibility and / or resilience to the material.

[0102] Within the context of the present disclosure, the term “shrinkage” refers to the ratio of: 1) the difference between the measured final density of the dried aerogel material or composition and the target density calculated from solid content in the sol-gel precursor solution, relative to 2) the target density calculated from solid content in the sol-gel precursor solution. Shrinkage can be calculated by the following equation: Shrinkage = [Final Density (g / cm3) -Target Density (g / cm3)] / [Target Density (g / cm3)]. Preferably, shrinkage of an aerogel material of the present disclosure is 50% or less, 25% or less, 10% or less, 8% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.1% or less, about 0.01% or less, or in a range between any two of these values.

[0103] Within the context of the present disclosure, the terms “thermal conductivity” and “TC” refer to a measurement of the ability of a material or composition to transfer heat between two surfaces on either side of the material or composition, with a temperature difference between the two surfaces. Thermal conductivity is specifically measured as the heat energy transferred per unit time and per unit surface area, divided by the temperature difference. It is typically recorded in SI units as mW / m*K (milliwatts per meter * Kelvin). The thermal conductivity of a material may be determined by methods known in the art, including, but not limited to: Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus (ASTM C518, ASTM International, West Conshohocken, PA); a Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus (ASTM C177, ASTM International, West Conshohocken, PA); a Test Method for Steady-State Heat Transfer Properties of Pipe Insulation (ASTM C335, ASTM International, West Conshohocken, PA); a Thin Heater Thermal Conductivity Test (ASTM Cl 114, ASTM International, West Conshohocken, PA); Determination of thermal resistance by means of guarded hot plate and heat flow meter methods (EN 12667, British Standards Institution, United Kingdom); or Determination of steady-state thermal resistance and related properties - Guarded hot plate apparatus (ISO 8203, International Organization for Standardization, Switzerland). Within the context of the present disclosure, thermal conductivity measurements are acquired according to ASTM C 177 standards, at a temperature of about 37.5°CAAI-100-B-PCT (1197-WOOl)at atmospheric pressure, and a compression of about 2 psi, unless otherwise stated. Preferably, aerogel materials or compositions of the present disclosure have a thermal conductivity of about 50 mW / mK or less, about 40 mW / mK or less, about 30 mW / mK or less, about 25 mW / mK or less, about 20 mW / mK or less, about 18 mW / mK or less, about 16 mW / mK or less, about 14 mW / mK or less, about 12 mW / mK or less, about 10 mW / mK or less, about 5 mW / mK or less, or in a range between any two of these values.

[0104] Within the context of the present disclosure, the term “density” refers to a measurement of the mass per unit volume of an aerogel material or composition. The term “density” generally refers to the true density of an aerogel material, as well as the bulk density of an aerogel composition. Density is typically recorded as kg / m3or g / cc. The density of an aerogel material or composition may be determined by methods known in the art, including, but not limited to: Standard Test Method for Dimensions and Density of Preformed Block and Board-Type Thermal Insulation (ASTM C303, ASTM International, West Conshohocken, PA); Standard Test Methods for Thickness and Density of Blanket or Batt Thermal Insulations (ASTM Cl 67, ASTM International, West Conshohocken, PA); or Determination of the apparent density of preformed pipe insulation (ISO 18098, International Organization for Standardization, Switzerland). Within the context of the present disclosure, density measurements are acquired according to ASTM Cl 67 standards, unless otherwise stated. Preferably, aerogel materials or compositions of the present disclosure have a density of about 0.60 g / cc or less, about 0.50 g / cc or less, about 0.40 g / cc or less, about 0.30 g / cc or less, about 0.25 g / cc or less, about 0.20 g / cc or less, about 0.18 g / cc or less, about 0.16 g / cc or less, about 0.14 g / cc or less, about 0.12 g / cc or less, about 0.10 g / cc or less, about 0.05 g / cc or less, about 0.01 g / cc or less, or in a range between any two of these values.

[0105] Within the context of the present disclosure, the term “hydrophobicity” refers to a measurement of the ability of an aerogel material or composition to repel water.

[0106] Hydrophobicity of an aerogel material or composition can be expressed in terms of the liquid water uptake. Within the context of the present disclosure, the term “liquid water uptake” refers to a measurement of the potential of an aerogel material or composition to absorb or otherwise retain liquid water. Liquid water uptake can be expressed as a percent (by weight or by volume) of water which is absorbed or otherwise retained by an aerogel material orAAI-100-B-PCT (1197-WOOl)composition when exposed to liquid water under certain measurement conditions. The liquid water uptake of an aerogel material or composition may be determined by methods known in the art, including, but not limited to: Standard Test Method for Determining the Water Retention (Repellency) Characteristics of Fibrous Glass Insulation (ASTM C1511, ASTM International, West Conshohocken, PA); Standard Test Method for Water Absorption by Immersion of Thermal Insulation Materials (ASTM C1763, ASTM International, West Conshohocken, PA); Thermal insulating products for building applications: Determination of short term water absorption by partial immersion (EN 1609, British Standards Institution, United Kingdom). Due to different methods possibly resulting in different results, it should be understood that within the context of the present disclosure, measurements of liquid water uptake are acquired according to ASTM C1511 standards, under ambient pressure and temperature, unless otherwise stated. In certain embodiments, aerogel materials or compositions of the present disclosure can have a liquid water uptake of according to ASTM C1511 of about 100 wt% or less, about 80 wt% or less, about 60 wt% or less, about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 8 wt% or less, about 5 wt% about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.1 wt% or less, or in a range between any two of these values. Aerogel materials or compositions of the present disclosure can have a liquid water uptake of according to ASTM Cl 763 of about 100 vol wt% or less, about 80 wt% or less, about 60 wt% or less, about 50 wt% or less, about 40 wt% or less, about 30 wt% or less, about 20 wt% or less, about 15 wt% or less, about 10 wt% or less, about 8 wt% or less, about 5 wt% about 3 wt% or less, about 2 wt% or less, about 1 wt% or less, about 0.1 wt% or less, or in a range between any two of these values. An aerogel material or composition which has improved liquid water uptake relative to another aerogel material or composition will have a lower percentage of liquid water uptake / retention relative to the reference aerogel materials or compositions.

[0107] Hydrophobicity of an aerogel material or composition can be expressed by measuring the equilibrium contact angle of a water droplet at the interface with the surface of the material. Aerogel materials or compositions of the present disclosure can have a water contact angle of about 90° or more, about 120° or more, about 130° or more, about 140° or more, about 150° or more, about 160° or more, about 170° or more, about 175° or more, or in a range between any two of these values.AAI-100-B-PCT (1197-WOOl)

[0108] Within the context of the present disclosure, the terms “heat of combustion” and “HOC” refer to a measurement of the amount of heat energy released in the combustion of an aerogel material or composition. Heat of combustion is typically recorded in calories of heat energy released per gram of aerogel material or composition (cal / g), or as megajoules of heat energy released per kilogram of aerogel material or composition (MJ / kg). The heat of combustion of a material or composition may be determined by methods known in the art, including, but not limited to: Reaction to fire tests for products - Determination of the gross heat of combustion (calorific value) (ISO 1716, International Organization for Standardization, Switzerland). Within the context of the present disclosure, heat of combustion measurements are acquired according to conditions comparable to ISO 1716 standards, unless otherwise stated. Preferably, aerogel compositions of the present disclosure can have a heat of combustion of about 750 cal / g or less, about 717 cal / g or less, about 700 cal / g or less, about 650 cal / g or less, about 600 cal / g or less, about 575 cal / g or less, about 550 cal / g or less, about 500 cal / g or less, about 450 cal / g or less, about 400 cal / g or less, about 350 cal / g or less, about 300 cal / g or less, about 250 cal / g or less, about 200 cal / g or less, about 150 cal / g or less, about 100 cal / g or less, about 50 cal / g or less, about 25 cal / g or less, about 10 cal / g or less, or in a range between any two of these values. An aerogel composition which has an improved heat of combustion relative to another aerogel composition will have a lower heat of combustion value, relative to the reference aerogel compositions. In certain embodiments of the present disclosure, the HOC of an aerogel composite is improved by incorporating a fire-class additive into the aerogel composite.

[0109] Within the context of the present disclosure, all thermal analyses and related definitions are referenced with measurements performed by starting at 25 °C and ramping at a rate of 20 °C per minute up to 1000 °C in air at ambient pressure. Accordingly, any changes in these parameters will have to be accounted for (or re-performed under these conditions) in measuring and calculating onset of thermal decomposition, temperature of peak heat release, temperature of peak hear absorption and the like. Within the context of the present disclosure, the terms “onset of thermal decomposition of hydrophobic organic material”, “onset of thermal decomposition” and “Ta” refer to a measurement of the lowest temperature of environmental heat at which rapid exothermic reactions from the decomposition of hydrophobic organic material appear within a material or composition. The onset of thermal decomposition of a material or composition may be measured using thermo-gravimetric analysis (TGA). The TGA curve of aAAI-100-B-PCT (1197-WOOl)material depicts the weight loss (%mass) of a material as it is exposed to an increase in surrounding temperature. The onset of thermal decomposition of a material can be correlated with the intersection point of the following tangent lines of the TGA curve: a line tangent to the base line of the TGA curve, and a line tangent to the TGA curve at the point of maximum slope during the rapid decomposition event related to the decomposition of hydrophobic organic material. Within the context of the present disclosure, measurements of the onset of thermal decomposition of hydrophobic organic material are acquired using TGA analysis as provided in this paragraph, unless otherwise stated.

[0110] The onset of thermal decomposition of a material may also be measured using differential scanning calorimetry (DSC) analysis. The DSC curve of a material depicts the heat energy (mW / mg) released by a material as it is exposed to a gradual increase in surrounding temperature. The onset of thermal decomposition temperature of a material can be correlated with the point in the DSC curve where the A mW / mg (change in the heat energy output) maximally increases, thus indicating exothermic heat production from the aerogel material. Within the context of the present disclosure, measurements of onset of thermal decomposition using DSC, TGA, or both are acquired using a temperature ramp rate of 20°C / min as further defined in the previous paragraph, unless otherwise stated expressly. DSC and TGA each provide similar values for this onset of thermal decomposition, and many times, the tests are run concurrently, so that results are obtained from both. In certain embodiments, aerogel materials or compositions of the present disclosure have an onset of thermal decomposition of about 300°C or more, about 320°C or more, about 340°C or more, about 360°C or more, about 380°C or more, about 400°C or more, about 415°C or more, about 420°C or more, about 440°C or more, about 460°C or more, about 480°C or more, about 500°C or more, about 550°C or more, about 575°C or more, about 600°C or more, or in a range between any two of these values. Within the context herein, for example, a first composition having an onset of thermal decomposition that is higher than an onset of thermal decomposition of a second composition, would be considered an improvement of the first composition over the second composition. It is contemplated herein that onset of thermal decomposition of a composition or material is increased when adding one or more fire-class additives, as compared to a composition that does not include any fire-class additives.AAI-100-B-PCT (1197-WOOl)

[0111] Within the context of the present disclosure, the terms “onset of thermal decomposition” refers to a measurement of the lowest temperature of environmental heat at which endothermic reactions from decomposition or dehydration appear within a material or composition. The onset of thermal decomposition of a material or composition may be measured using thermo-gravimetric analysis (TGA). The TGA curve of a material depicts the weight loss (%mass) of a material as it is exposed to an increase in surrounding temperature. The onset of thermal decomposition of a material may be correlated with the intersection point of the following tangent lines of the TGA curve: a line tangent to the base line of the TGA curve, and a line tangent to the TGA curve at the point of maximum slope during the rapid endothermic decomposition or dehydration of the material. Within the context of the present disclosure, measurements of the onset of endothermic decomposition of a material or composition are acquired using TGA analysis as provided in this paragraph, unless otherwise stated.

[0112] Aerogel precursor materials

[0113] An aerogel framework can be made from a range of precursor materials, including inorganic precursor materials (such as precursors used in producing silica-based aerogels); organic precursor materials (such precursors used in producing carbon-based aerogels); hybrid inorganic / organic precursor materials; and combinations thereof. Within the context of the present disclosure, the term "amalgam aerogel" refers to an aerogel produced from a combination of two or more different gel precursors. Within the context of the present disclosure, the terms "framework" or "framework structure" refer to the network of interconnected oligomers, polymers or colloidal particles that form the solid structure of a gel or an aerogel. The polymers or particles that make up the framework structures typically have a diameter of about 100 angstroms. However, framework structures of the present disclosure can also include networks of interconnected oligomers, polymers or colloidal particles of all diameter sizes that form the solid structure within in a gel or aerogel. Furthermore, the terms "silica-based aerogel" or "silica-based framework" refer to an aerogel framework in which silica comprises at least 50% (by weight) of the oligomers, polymers or colloidal particles that form the solid framework structure within in the gel or aerogel.

[0114] Inorganic aerogels are generally formed from metal oxide or metal alkoxide materials. The metal oxide or metal alkoxide materials can be based on oxides or alkoxides ofAAI-100-B-PCT (1197-WOOl)any metal that can form oxides. Such metals include, but are not limited to silicon, aluminum, titanium, zirconium, hafnium, yttrium, vanadium, cerium, and the like. Inorganic silica aerogels are traditionally made via the hydrolysis and condensation of silica-based alkoxides, or via gelation of silicic acid or water glass. Inorganic precursor materials for silica based aerogel synthesis include, but are not limited to: metal silicates such as sodium silicate or potassium silicate; alkoxysilanes such as tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and tetra-n-propoxysilane; partially hydrolyzed alkoxysilanes such as partially hydrolyzed TEOS and partially hydrolyzed TMOS; condensed polymers of alkoxysilanes such as condensed polymers of TEOS and condensed polymers of TMOS; alkylalkoxy silanes, and combinations thereof.

[0115] In certain aspects of the present disclosure, pre-hydrolyzed TEOS, such as Silbond H-5 (SBH5, Silbond Corp), which is hydrolyzed with a water / silica ratio of about 1.9-2, may be used as commercially available or may be further hydrolyzed prior to incorporation into the gelling process. Partially hydrolyzed TEOS or TMOS, such as polyethysilicate (Silbond 40) or polymethylsilicate may also be used as commercially available or may be further hydrolyzed prior to incorporation into the gelling process.

[0116] Inorganic aerogels can also include gel precursors which comprise at least one hydrophobic group, such as alkyl metal alkoxides, cycloalkyl metal alkoxides, and aryl metal alkoxides, which can impart or improve certain properties in the gel such as stability and hydrophobicity. Within the context of the present disclosure, the term "hydrophobicity" refers to a measurement of the ability of an aerogel material or composition to repel water. Hydrophobicity of an aerogel material or composition can be expressed by measuring the equilibrium contact angle of a water droplet at the interface with the surface of the material. Aerogel materials or compositions of the present disclosure that have a water contact angle greater than 90° are considered hydrophobic. Aerogel materials or compositions that have a water contact angle that is less than 90° are considered hydrophilic.

[0117] Inorganic silica aerogels can specifically include hydrophobic precursors such as alkylsilanes or arylsilanes. Hydrophobic gel precursors can be used as primary precursor materials to form the framework of a gel material. However, hydrophobic gel precursors are more commonly used as co-precursors in combination with metal alkoxides in the formation of amalgam aerogels. Hydrophobic inorganic precursor materials for silica based aerogel synthesisAAI-100-B-PCT (1197-WOOl)include, but are not limited to: trimethyl methoxysilane [TMS], dimethyl dimethoxysilane [DMS], methyl trimethoxysilane [MTMS], trimethyl ethoxysilane, dimethyl diethoxysilane [DMDES], methyl triethoxysilane [MTES], ethyl triethoxysilane [ETES], diethyl diethoxysilane, ethyl triethoxysilane, propyl trimethoxysilane, propyl tri ethoxy si lane, phenyl trimethoxysilane, phenyl triethoxysilane [PhTES], hexamethyldisilazane and hexaethyl di sil azane.

[0118] In exemplary aspects of the present disclosure, the relative amount of hydrophobic gel precursor or precursors to other inorganic precursor materials is selected to provide an aerogel material or composition having hydrophobic properties as disclosed herein while maintaining other properties such as thermal conductivity, heat of combustion, onset of thermal decomposition, and / or processability. The present inventors have made the surprising realization that the amount of hydrophobic gel precursor can be increased compared with conventional processes, to prepare novel aerogel materials having enhanced resilience shown by compression set testing, even without the need for a subsequent annealing step. In exemplary aspects, hydrophobic aerogel materials and compositions of the present disclosure can be prepared from silica gel precursor materials having a content of hydrophobic inorganic precursor material of more than about 36 wt.% or contents in the ranges of up to 90 wt.%, 40-80 wt.% or 50-70 wt.%. Further details regarding the synthesis and characterization of hydrophobic aerogels are described in U. S. Patent Application Publication No. 2016 / 0096949 to Evans et al, which is incorporated herein by reference.

[0119] Within the context of the present disclosure, content in wt.% of hydrophobic inorganic precursor material is defined based on the ratio of the weight contribution of hydrolysis product of hydrophobic gel precursor to the total weight contribution of all solids after hydrolysis. Table 1, below, illustrates exemplary compositions including TEOS, DMDES and MTES that provide a hydrophobe content of about 34 wt.%, 36 wt.% and 38 wt.%.AAI-100-B-PCT (1197-WOOl)HydrophobeContent TEOS TEOS DMDES DMDES MTES MTES(wt.%) (grams) (moles) (grams) (moles) (grams) (moles)38% 100 0.480 5.29 0.036 39.90 0.22436% 100 0.480 4.86 0.033 36.62 0.20534% 100 0.480 4.45 0.030 33.54 0.188TABLE 1Table 2, below, illustrates exemplary compositions including S40, DMDES and MTES that provide a hydrophobe content of about 34 wt.%, 36 wt.% and 38 wt.%.HydrophobeSilbond Silbond DMDES, DMDES, MTES, MTES, content,40 40, mol mol molwt.% g g38 100 - 7.35 0.050 55.43 0.31136 100 - 6.75 0.046 50.87 0.28534 100 - 6.18 0.042 46.59 0.261TABLE 2

[0120] Conventional aerogels may also be treated to impart or improve hydrophobicity. However, aerogel compositions according to the present disclosure have hydrophobic properties without any necessary additional treatment to provide such properties. Typically, a known gel precursor having an MTES content of around 33 wt.% or more will result in an intrinsically hydrophobic aerogel without addition of a hydrophobic agent such as TMS in the aging fluid. However, when the level of MTES is less than around 33 wt.%, supplementary hydrophobic agent must be added to the aging fluid when aging under known conditions (e.g. at 68 °C) to produce a (non-intrinsically) hydrophobic aerogel. Within the context of the present disclosure, the term “intrinsically hydrophobic” refers to aerogels having hydrophobic properties according to aspects disclosed herein without treatment, e.g., treatment of the wet gel and / or treatment of the dried aerogel form, to impart or improve hydrophobicity.

[0121] For example, aerogels and aerogel compositions according to aspects disclosed herein can have hydrophobic properties in combination with other disclosed properties, e.g., heat of combustion, onset of thermal decomposition, or combinations of such properties, based solelyAAI-100-B-PCT (1197-WOOl)on hydrophobicity provided by components of the gel precursors. In such aspects, the gel precursors provide an amount of hydrophobic-bound silicon sufficient to provide an aerogel composition having hydrophobicity in terms of the ranges of liquid water uptake and water vapor uptake disclosed herein without further treatment with a hydrophobizing agent (such as HMDZ).

[0122] Within the context of the present disclosure, the term “hydrophobic-bound silicon” refers to a silicon atom within the framework of a gel or aerogel which comprises at least one hydrophobic group covalently bonded to the silicon atom. Examples of hydrophobic-bound silicon include, but are not limited to, silicon atoms in silica groups within the gel framework which are formed from gel precursors comprising at least one hydrophobic group (such as MTES or DMDES). In exemplary embodiments, aerogel compositions resulting from the hydrophobic gel precursor or precursors disclosed herein can have surface groups that include hydrophobic groups of the formula Si-R, where R is an alkyl group. For example, hydrophobic groups of the present disclosure include, but are not limited to, methyl groups, ethyl groups, propyl groups, isopropyl groups, butyl groups, isobutyl groups, tertbutyl groups, octyl groups, phenyl groups, or other substituted or unsubstituted hydrophobic organic groups known to those with skill in the art. Within the context of the present disclosure, the terms “hydrophobic group,” “hydrophobic organic material,” and “hydrophobic organic content” specifically exclude readily hydrolysable organic silicon-bound alkoxy groups on the framework of the gel material which are the product of reactions between organic solvents and silanol groups. Such excluded groups are distinguishable from hydrophobic organic content of this disclosure through NMR analysis.

[0123] Within the context of the present disclosure, the terms “aliphatic hydrophobic group,” “aliphatic hydrophobic organic material,” and “aliphatic hydrophobic organic content” describe hydrophobic groups on hydrophobic-bound silicon which are limited to aliphatic hydrocarbons, including, but not limited to hydrocarbon moi eties containing 1-40 carbon atoms which can be saturated or unsaturated (but not aromatic), which can include straight-chain, branched, cyclic moieties (including fused, bridging, and spiro-fused polycyclic), or combinations thereof, such as alkyl, alkenyl, alkynyl, (cycloalkyl)alkyl, (cycloalkenyl)alkyl, or (cycloalkyl)alkenyl moieties, and hetero-aliphatic moieties (wherein one or more carbon atoms are independently replaced by one or more atoms selected from the group consisting of oxygen, sulfur, nitrogen, or phosphorus). In certain embodiments of the present disclosure, at least 50%AAI-100-B-PCT (1197-WOOl)of the hydrophobic organic material in the aerogel composition comprises aliphatic hydrophobic groups.

[0124] The amount of hydrophobic-bound silicon contained in an aerogel can be analyzed using NMR spectroscopy, such as CP / MAS29Si Solid State NMR. An NMR analysis of an aerogel allows for the characterization and relative quantification of: M-type hydrophobicbound silicon (monofunctional silica, such as TMS derivatives); D-type hydrophobic-bound silicon (bifunctional silica, such as DMDES derivatives); T-type hydrophobic-bound silicon (trifunctional silica, such as MTES derivatives); and Q-type silicon (quadfunctional silica, such as TEOS derivatives). NMR analysis can also be used to analyze the bonding chemistry of hydrophobic-bound silicon contained in an aerogel by allowing for categorization of specific types of hydrophobic-bound silicon into sub-types (such as the categorization of T-type hydrophobic-bound silicon into T1species, T2species, and T3species). Specific details related to the NMR analysis of silica materials can be found in the article “Applications of Solid-State NMR to the Study of Organic / Inorganic Multicomponent Materials” by Geppi et al., specifically pages 7-9 (Appl. Spec. Rev. (2008), 44-1: 1-89), which is hereby incorporated by reference according to the specifically cited pages.

[0125] The characterization of hydrophobic-bound silicon in a CP / MAS29Si NMR analysis can be based on the following chemical shift peaks: M1(30 to 10 ppm); D1(10 to -10 ppm), D2(-10 to -20 ppm); T1(-30 to -40 ppm), T2(-40 to -50 ppm), T3(-50 to -70 ppm); Q2(-70 to -85 ppm), Q3(-85 to -95 ppm), Q4(-95 to -110 ppm). These chemical shift peaks are approximate and exemplary and are not intended to be limiting or definitive. The precise chemical shift peaks attributable to the various silicon species within a material can depend on the specific chemical components of the material, and can generally be deciphered through routine experimentation and analysis by those in the art.

[0126] The aerogel materials of the present disclosure can have a ratio of T1-2: T3of between about 0.01 and about 0.5, between about 0.01 and about 0.3, or between about 0.1 and about 0.3. A ratio of T1-2: T3represents a ratio of a combination of T1and T2species relative to T3species. The amount of T1, T2and T3can quantified by the integral of the individual chemical shift peaks respectively associated with T1species, T2species or T3species in a29Si NMR analysis, as previously defined. The aerogel materials of the present disclosure can have a ratioAAI-100-B-PCT (1197-WOOl)of Q2'3: Q4of between about 0.1 and 2.5, between about 0.1 and 2.0, between about 0.1 and 1.5, between about 0.1 and 1.0, or between about 0.5 and 1.0. A ratio of Q2'3: Q4represents a ratio of a combination of Q2and Q3species relative to Q4species. The amount of Q2, Q3and Q4can quantified by the integral of the individual chemical shift peak respectively associated with Q2species, Q3species or Q4species in a29Si NMR analysis, as previously defined.

[0127] Within the context of the present disclosure, the term “hydrophobic organic content” or “hydrophobe content” or “hydrophobic content” refers to the amount of hydrophobic organic material bound to the framework in an aerogel material or composition. The hydrophobic organic content of an aerogel material or composition can be expressed as a weight percentage of the amount of hydrophobic organic material on the aerogel framework relative to the total amount of material in the aerogel material or composition. Hydrophobic organic content can be calculated by those with ordinary skill in the art based on the nature and relative concentrations of materials used in producing the aerogel material or composition. Hydrophobic organic content can also be measured using thermo-gravimetric analysis (TGA) in an inert atmosphere. Specifically, the percentage of hydrophobic organic material in an aerogel can be correlated with the percentage of weight loss in a hydrophobic aerogel material or composition when subjected to combustive heat temperatures during a TGA analysis, with adjustments being made for the loss of moisture, loss of residual solvent, and the loss of readily hydrolysable alkoxy groups during the TGA analysis. Other alternative techniques such as differential scanning calorimetry, elemental analysis (particularly, carbon), chromatographic techniques, nuclear magnetic resonance spectra and other analytical techniques known to person of skilled in the art may be used to measure and determine hydrophobe content in the aerogel compositions of the present invention. In certain instances, a combination of the known techniques may be useful or necessary in determining the hydrophobe content of the aerogel compositions of the present invention.

[0128] The term “fuel content” refers to the total amount of combustible material in an aerogel material or composition, which can be correlated with the total percentage of weight loss in an aerogel material or composition when subjected to combustive heat temperatures during a TGA or TG-DSC analysis, with adjustments being made for the loss of moisture. The fuel content of an aerogel material or composition can include hydrophobic organic content, as well as otherAAI-100-B-PCT (1197-WOOl)combustible materials such as residual alcoholic solvents, filler materials, reinforcing materials, and readily hydrolysable alkoxy groups.

[0129] In certain aspects, aerogels of the present disclosure are inorganic silica aerogels formed primarily from prepolymerized silica precursors preferably as oligomers, or hydrolyzed silicate esters formed from silicon alkoxides in an alcohol solvent. In certain embodiments, such prepolymerized silica precursors or hydrolyzed silicate esters may be formed in situ from other precursors or silicate esters such as alkoxy silanes or water glass. However, the disclosure as a whole may be practiced with any other aerogel compositions known to those in the art and is not limited to any one precursor material or amalgam mixture of precursor materials.

[0130] As discussed in general above, in exemplary aspects of the present disclosure, aerogels can be formed from gel precursors or combinations of gel precursors which comprise at least one hydrophobic group. Such aerogels, e.g., inorganic aerogels such as silica-based aerogels, can include hydrophobic-bound silicon. For example, the source of the hydrophobicbound silicon in the aerogel can be the hydrophobic precursor material or materials. In the present disclosure, aerogels formed from such precursors can be hydrophobic. In some embodiments, aerogels formed from such precursors can be intrinsically hydrophobic.

[0131] For example, conventional aerogels can be treated to impart or improve hydrophobicity. Hydrophobic treatment can be applied to a sol-gel solution, a wet-gel prior to liquid phase extraction, or to an aerogel after liquid phase extraction. Hydrophobic treatment can be carried out by reacting a hydroxy moiety on a gel, such as a silanol group (Si-OH) present on a framework of a silica gel, with a functional group of a hydrophobizing agent. The resulting reaction converts the silanol group and the hydrophobizing agent into a hydrophobic group on the framework of the silica gel. The hydrophobizing agent compound can react with hydroxyl groups on the gel according the following reaction: '. MX i \ (hydrophobizing agent) + MOH (silanol) MOMRN (hydrophobic group) + FIX. Hydrophobic treatment can take place both on the outer macro-surface of a silica gel, as well as on the inner-pore surfaces within the porous network of a gel. Published US Pat. App. 2016 / 0096949 Al (Paragraphs

[0044] -

[0048] ) teaches hydrophobic treatments and is hereby incorporated by reference according to the individually cited paragraphs. However, as discussed above, aerogels according to the present disclosure areAAI-100-B-PCT (1197-WOOl)inherently hydrophobic without hydrophobic treatment, e.g., without treatment by a hydrophobizing agent.

[0132] Production of an aerogel generally includes the following steps: i) formation of a sol-gel solution; ii) formation of a gel from the sol-gel solution; and iii) extracting the solvent from the gel materials to obtain a dried aerogel material. This process is discussed below in greater detail, specifically in the context of forming inorganic aerogels such as silica aerogels. However, the specific examples and illustrations provided herein are not intended to limit the present disclosure to any specific type of aerogel and / or method of preparation. The present disclosure can include any aerogel formed by any associated method of preparation known to those in the art.

[0133] Forming precursor sols

[0134] The first step in forming an inorganic aerogel is generally the formation of a precursor solution through hydrolysis and condensation of metal alkoxide precursors in an alcohol -based solvent. Major variables in the formation of inorganic aerogels include the type of alkoxide precursors included in the precursor solution, the nature of the solvent, the processing temperature and pH of the precursor solution (which may be altered by addition of an acid or a base), and precursor / solvent / water ratio within the precursor solution. Control of these variables in forming a precursor solution can permit control of the growth and aggregation of the gel framework during the subsequent transition of the gel material from the “sol” state to the “gel” state. While properties of the resulting aerogels are affected by the pH of the precursor solution and the molar ratio of the reactants, any pH and any molar ratios that permit the formation of gels may be used in the present disclosure.

[0135] A precursor solution is formed by combining at least one gelling precursor with a solvent. Suitable solvents for use in forming a precursor solution include lower alcohols with 1 to 6 carbon atoms including any integer therebetween, preferably 2 to 4, although other solvents can be used as known to those with skill in the art. Examples of useful solvents include, but are not limited to: methanol, ethanol, isopropanol, ethyl acetate, ethyl acetoacetate, acetone, dichloromethane, tetrahydrofuran, and the like. Multiple solvents can also be combined to achieve a desired level of dispersion or to optimize properties of the gel material. Selection of optimal solvents for the sol-gel and gel formation steps thus depends on the specific precursors,AAI-100-B-PCT (1197-WOOl)fillers and additives being incorporated into the sol-gel solution; as well as the target processing conditions for gelling and liquid phase extraction, and the desired properties of the final aerogel materials.

[0136] Water can also be present in the precursor solution. The water acts to hydrolyze the metal alkoxide precursors into metal hydroxide precursors. The hydrolysis reaction can be (using TEOS in ethanol solvent as an example).Si(OC2H5)4+ 4H2O - Si(OH)4+ 4(C2H5OH) (1)

[0137] The resulting hydrolyzed metal hydroxide precursors remain suspended in the precursor solution in a "sol" state, either as individual molecules or as small polymerized (or oligomarized) colloidal clusters of molecules. For example, polymerization / condensation of the Si(OH)4 precursors can occur as follows:2 Si(OH)4(OH)3Si-O-Si(OH)3 + H2O (2)This polymerization can continue until colloidal clusters of polymerized (or oligomarized) SiO2(silica) molecules are formed.

[0138] Acids and bases can be incorporated into the precursor solution to control the pH of the precursor solution, and to catalyze the hydrolysis and condensation reactions of the precursor materials. While any acid may be used to catalyze precursor reactions and to obtain a lower pH solution, preferable acids include: HC1, H2SO4, H3PO4, oxalic acid and acetic acid.

[0139] Any base may likewise be used to catalyze precursor reactions and to obtain a higher pH solution. In an aspect of the present disclosure bases can be used to catalyze the precursor reactions or adjust the pH of the precursor solution. In an aspect of the present disclosure, metal hydroxide bases can be used to catalyze the precursor reactions or adjust the pH of the precursor solution. Exemplary metal hydroxide bases include, but are not limited to, sodium hydroxide, lithium hydroxide, calcium hydroxide, potassium hydroxide, strontium hydroxide, and barium hydroxide. In another aspect of the present disclosure, amine bases can be used to be used to catalyze precursor reactions and / or adjust the pH of the precursor solution. Exemplary amine bases include, but are not limited to, tetraalkylammonium hydroxides, choline hydroxide, trialkylamines, amidines, guanidines and imidazoles. Specific examples of amineAAI-100-B-PCT (1197-WOOl)bases include tetramethylammonium hydroxide, tetrabutylammonium hydroxide, guanidine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), l,4-diazabicyclo[2.2.2]octane (DABCO), pyridine, imidazole, and 4,5-dihydroimidazole.

[0140] The precursor solution can include additional co-gelling precursors, as well as filler materials and other additives. Filler materials and other additives may be dispensed in the precursor solution at any point before or during the formation of a gel. Filler materials and other additives may also be incorporated into the gel material after gelation through various techniques known to those in the art. Preferably, the precursor solution comprising the gelling precursors, solvents, catalysts, water, filler materials and other additives is a homogenous solution which is capable of effective gel formation under suitable conditions.

[0141] Gelation

[0142] Once a precursor solution has been formed and optimized, the gel-forming components in the precursor solution can be transitioned into a gel material. The process of transitioning gel-forming components into a gel material comprises an initial gel formation step wherein the gel solidifies up to the gel point of the gel material. The gel point of a gel material may be viewed as the point where the gelling solution exhibits resistance to flow and / or forms a substantially continuous polymeric framework throughout its volume. A range of gel-forming techniques are known to those in the art. Examples include but are not limited to: maintaining the mixture in a quiescent state for a sufficient period of time; adjusting the pH of the solution; adjusting the temperature of the solution; directing a form of energy onto the mixture (ultraviolet, visible, infrared, microwave, ultrasound, particle radiation, electromagnetic); or a combination thereof.

[0143] In certain embodiments, gel materials of the present disclosure can be produced through a continuous casting and gelation process. In a continuous casting process, a continuous sheet of fibrous material can be used as a support during a continuous casting process. The fibrous support can improve the flexibility and / or strength of the aerogel material. In an aspect of the present disclosure an aerogel composite is formed by adding a gel precursor composition to a fiber reinforcing material and forming a wet gel from the gel precursor composition. In an aspect of the present disclosure, the precursor solution is incorporated into a fiber reinforcement material and the resulting composite material formed into a fiber supported wet gel material.AAI-100-B-PCT (1197-WOOl)

[0144] During large scale production of an aerogel, the fiber reinforcement material is in the form of a continuous sheet of interconnected or interlaced fiber reinforcement materials. The precursor solution is incorporated into the aerogel composite as continuous sheet of interconnected or interlaced fiber reinforcement materials. The initial wet gel material is produced as a continuous sheet of fiber reinforced gel by casting or impregnating a gel precursor solution into a continuous sheet of an interconnected or an interlaced fiber reinforcement material. As will be described in more detail, the liquid phase may then be at least partially extracted from the fiber-reinforced wet gel material to produce a sheet-like, fiber reinforced aerogel composite.

[0145] Aerogel composites may be fiber-reinforced with various fiber reinforcement materials to achieve a more flexible, resilient and conformable composite product. Fiber reinforcement materials may be in the form of discrete fibers, woven materials, non-woven materials, battings, webs, mats, and felts. Fiber reinforcements can be made from organic fibrous materials, inorganic fibrous materials, or combinations thereof. Fiber reinforcement materials can comprise a range of materials, including, but not limited to: polyesters, polyolefin terephthalates, poly( ethylene) naphthalate, polycarbonates (examples Rayon, Nylon), cotton, (e.g. lycra manufactured by DuPont), carbon (e.g. graphite), polyacrylonitriles (PAN), oxidized PAN, uncarbonized heat treated PANs (such as those manufactured by SGL carbon), fiberglass based material (like S-glass, 901 glass, 902 glass, 475 glass, E-glass,) silica based fibers like quartz, (e.g. Quartzel manufactured by Saint-Gobain), Q-felt (manufactured by Johns Manville), Saffil (manufactured by Saffil), Durablanket (manufactured by Unifrax) and other silica fibers, Duraback (manufactured by Carborundum), Polyaramid fibers like Kevlar, Nomex, Sontera (all manufactured by DuPont), Conex (manufactured by Taijin), polyolefins like Tyvek (manufactured by DuPont), Dyneema (manufactured by DSM), Spectra (manufactured by Honeywell), other polypropylene fibers like Typar, Xavan (both manufactured by DuPont), fluoropolymers like PTFE with trade names as Teflon (manufactured by DuPont), Goretex (manufactured by W. L. GORE), silicon carbide fibers like Nicalon (manufactured by COI Ceramics), ceramic fibers like Nextel (manufactured by 3M), acrylic polymers, wool fibers, silk, hemp, leather, suede, PBO -Zylon fibers (manufactured by Tyobo), liquid crystal material like Vectan (manufactured by Hoechst), Cambrelle fiber (manufactured by DuPont), polyurethanes, polyamides, metal fibers such as boron, aluminum, iron, and stainless steel fibers, andAAI-100-B-PCT (1197-WOOl)thermoplastics like PEEK, PES, PEI, PEK, PPS. Aerogel composites of the present disclosure can have a thickness of 15 mm or less, 10 mm or less, 5 mm or less, 3 mm or less, 2 mm or less, or 1 mm or less.

[0146] Aerogel composites of the present disclosure can have a thickness of 15 mm or less, 10 mm or less, 5 mm or less, 3 mm or less, 2 mm or less, or 1 mm or less.

[0147] In an aspect of the present disclosure, the aerogel composite may include an opacifying additive to reduce the radiative component of heat transfer. At any point prior to gel formation, opacifying compounds or precursors thereof may be dispersed into the mixture comprising gel-forming material. Exemplary opacifying additives include, but are not limited to, B4C, Diatomite, Manganese ferrite, MnO, NiO, SnO, Ag2O, EfeCh, TiC, WC, carbon black, titanium oxide, iron titanium oxide, zirconium silicate, zirconium oxide, iron (I) oxide, iron (III) oxide, manganese dioxide, iron titanium oxide (ilmenite), chromium oxide, silicon carbide, or mixtures thereof.

[0148] Aging

[0149] The process of transitioning gel-forming components into a gel material in the present disclosure also includes an aging step (also referred to as curing) prior to liquid phase extraction. Aging a gel material after it reaches its gel point can further strengthen the gel framework by increasing the number of cross-linkages within the network. The duration of gel aging can be adjusted to control various properties within the resulting aerogel material. This aging procedure can be useful in preventing potential volume loss and shrinkage during liquid phase extraction. Aging can involve maintaining the gel (prior to extraction) at a quiescent state for an extended period; maintaining the gel at elevated temperatures; adding cross-linkage promoting compounds; or any combination thereof.

[0150] The time for transitioning gel-forming materials into a gel material includes both the duration of the initial gel formation (from initiation of gelation up to the gel point), as well as the duration of any subsequent curing and aging of the gel material prior to liquid phase extraction (from the gel point up to the initiation of liquid phase extraction). The total time period for transitioning gel-forming materials into a wet-gel material is typically between about 30 seconds and several days, preferably about 30 hours or less, about 24 hours or less, about 15AAI-100-B-PCT (1197-WOOl)hours or less, about 10 hours or less, about 6 hours or less, about 4 hours or less, about 2 hours or less, about 1 hour or less, about 30 minutes or less, or about 15 minutes or less. Ideally, the total time is minimized to allow efficient production of an aerogel. In particular, the inventors have found that a time of from around 30 seconds to around 120 seconds, and preferably 90 seconds, strikes a balance of allowing sufficient time for the gel precursor to infiltrate the fibers of a reinforcement material (e.g. fibers) while avoiding the creation of weaker wet gels and aerogels.

[0151] Aging of the wet gel material can be accomplished by heating the wet gel material for a time sufficient to complete the aging process. In a typical aging process, a wet gel material is placed into an aging vessel. The wet gel material is then heated to an aging temperature and maintained at the aging temperature until the aging process is complete. Optionally, the wet gel material can be washed with an aging fluid prior to, and during, heating. The aging fluid can be used to replace the primary reaction solvent present in the wet gel. Exemplary aging fluids are Ci-Ce alcohols, cyclic alcohols, alicyclic alcohols, aromatic alcohols, polyhydric alcohols, ethers, ketones, or cyclic ethers. Preferred aging fluids include methanol and ethanol. During aging, aging fluid can be substantially continuously passed over and / or through the wet gel material and through the aging vessel. The aging fluid passing through the aging vessel and the wet gel can be fresh aging fluid or recycled aging fluid.

[0152] The amount of time needed to complete the aging process is related to the aging temperature of the wet gel material. Generally, the higher the aging temperature the faster the aging process is completed. However, in conventional processes, the maximum temperature that could be used was limited to the liquid present in the wet gel material. Under atmospheric pressure (1 atm, 101,325 Pa) the aging temperature was previously limited to the boiling point of the liquid in the wet gel material. Furthermore, it was seen as undesirable to heat the aging material at or near the boiling point of the liquid in case evaporation of the aging fluid as the aging fluid is heated at or near the boiling point of the aging fluid caused damage to the framework structure of the wet gel material. To reduce the chance of damaging the wet gel material, in previous methods the aging process was typically conducted below the boiling point of the aging fluid in the wet gel material. For example, when using ethanol as the aging fluid, a wet gel material was typically aged at a temperature of 160 °F (71.1 °C), which is below theAAI-100-B-PCT (1197-WOOl)boiling point of ethanol (173 °F (78.3 °C) at 1 atm (101,325 Pa)) for a time of from 1 hour up to 24 hours.

[0153] Previous attempts to reduce the aging time of a wet gel material involved increasing the aging temperature of the wet gel material with the simultaneous application of external pressure to above the vapor pressure of the aging fluid. While the aging temperature was generally limited to the normal boiling point of the aging fluid, the temperature could be increased beyond the normal boiling point of the aging fluid by increasing the pressure in the aging vessel. When the pressure inside the aging vessel (the “aging pressure”) is maintained above the vapor pressure of the aging fluid, the temperature of the aging fluid could be increased beyond the normal boiling point of the aging fluid without boiling of the aging fluid. For example, prior art aging processes have typically used increased pressures of, for example, 1,000 to 2,500 psi (6.89 to 17.24 MPa) through the application of pressure from outside the system. As used herein, the “normal boiling point” of a liquid is the temperature at which the liquid boils at 1 atm (0.10 MPa).

[0154] For example, United States patent number 5,753,305 describes a rapid aging technique where the aging fluid is water, at an elevated pressure and a temperature greater than 100 °C, being the boiling point of water. Low boiling point liquids such as ethanol are removed prior to aging, unlike the present disclosure in which solvents such as ethanol are preferred. In fact, the disclosure of US 5,753,305 relates to aging of thin (micron level) aerogel films rather than bulk materials and seeks to provide a vapor phase aging with water which avoids liquid immersion, unlike the present disclosure.

[0155] Fang He et al. “Modified aging process for silica aerogel”, Journal of Materials Processing Technology, 209 (2009) 1621-1626 also reports attempts to improve aerogel performance by modifying the aging method. The authors aged TEOS-derived silica aerogel at high temperature and pressure using an ethanol / TEOS mixed aging fluid to shorten aging time and improve performance. However, the method required the addition of large amounts of additional TEOS monomer to the aging solution (15 vol.% TEOS to 84 vol.% ethanol and 1 vol.% deionized water) as well as the use of an autoclave to apply higher temperature and pressure. This method does not appear to be suitable for bulk aerogel synthesis.AAI-100-B-PCT (1197-WOOl)

[0156] US patent number 5,023,208 also describes a hydrothermal aging treatment using water as aging fluid at temperatures of 100 to 300 °C and high pressure being developed as a result of the elevated temperatures, in an autoclave. Again, the use of an autoclave precludes bulk (industrial quantity) synthesis, and the method uses a hydrothermal aging technique dissimilar to the present disclosure.

[0157] On the contrary, the present inventors have found that advantageous processes and products can be obtained by aging a wet gel at a temperature above the normal boiling point of the aging fluid and without the additional application of external pressure, for example without pressurization by inserting carbon dioxide into the aging vessel. This means that no other external source of pressurization is needed, and the aging vessel may only pressurize due optionally to pressurization of gas / air (if present) in the headspace of the vessel when being filled with aging fluid and due to increased vapor pressure within the closed aging vessel as the aging fluid is heated. Further pressurization may be provided by thermal expansion of the aging fluid as it is heated within the closed and sealed aging vessel. By introducing the wet gel and aging fluid into a closed vessel and heating the system to beyond the normal boiling point of the aging fluid, the pressure within the closed vessel increases such that the aging fluid does not boil, thereby avoiding damaging the wet gel material. For example, when using ethanol as the aging fluid, the aging may be performed in a closed vessel at an aging temperature of greater than 100 °C, beyond the normal boiling point of ethanol (78.3 °C), without the ethanol boiling.

[0158] An important finding by the inventors is that improved aerogel materials can be obtained through aging at high temperature (i.e. higher than the boiling point of the aging fluid at room temperature and pressure) and without applying additional pressure. Pressure is only developed due to the aging vessel being a closed vessel, and the contents being heated. As above, pressure develops due to increased vapor pressure of the aging fluid, thermal expansion of the aging fluid within the vessel and increased pressure from gases in the headspace of the vessel both when being heated and due to compression of said headspace gases as aging liquid is pumped into the closed vessel. The pressure which develops in the aging vessel can vary considerably due to experimental conditions. For example, on a laboratory scale, in a vessel with a small headspace, a developed pressure of 117 - 690 kPa (17 - 100 psi) or about 340 kPa (50 psi) may be typical. On the other hand, on an industrial or pilot scale with a larger aging vesselAAI-100-B-PCT (1197-WOOl)having more headspace, pressures well over 6,895 kPa (1,000 psi) may develop. However, the inventors have achieved excellent material properties under both laboratory and industrial conditions, indicating that the developed pressure is not a primary factor in this success; rather, the step of heating beyond boiling point but without boiling appears to be key.

[0159] In an aspect of the present disclosure, a wet gel material is placed in a vessel that can be closed to withstand a generated pressure. The vessel also includes an input for the aging fluid and an output for fluid to leave the vessel. The vessel is sealed, and aging fluid is introduced into the vessel, which may serve to pressurize the vessel by compression of any headspace gases such as air, for example up to a pressure of around 100 psi (690 kPa). The aging fluid may be the same fluid or a different fluid from the fluid used to make the wet gel material. In preferred aspects of the disclosure, the aging fluid is an alcohol (e.g., ethanol). The aging fluid is heated without additionally increasing the pressure inside the vessel above the vapor pressure of the aging fluid. The aging fluid can be heated by heating elements situated in or proximate to the vessel. Preferably the aging vessel has its own sources of heating and cooling so that the vessel does not need to be placed in a separate oven to provide heating.

[0160] In an aspect of the present disclosure, during aging of the wet gel material, aging fluid can be removed, and aging fluid can be introduced substantially continuously. For example, aging fluid can be recirculated through the vessel. The aging fluid can be heated outside of the vessel before being reintroduced into the vessel. During aging, the pressure inside the vessel (the “aging pressure”) increases due to heating of the aging fluid increasing the vapor pressure of the aging fluid. However, the aging pressure cannot exceed the vapor pressure of the liquid at the aging temperature because the vessel is closed. For example, in the present disclosure the pressure within the vessel may rise to around 1,300-1,800 psi (9 MPa - 12.4 MPa) when heated to around 100 - 110 °C using an industrial scale pressure vessel for aging as described above.

[0161] Table 3 provides a vapor pressure-temperature table for ethanol. Such a table can be used to determine the pressure which develops inside the vessel when the temperature of the aging fluid is increased to the desired aging temperature. For example, if an aging temperature of 230 F (110 °C) is desired, the vapor pressure inside the vessel will develop to an equilibrium pressure of 315 kPa and the liquid does not begin to damage the framework structure due to boiling.AAI-100-B-PCT (1197-WOOl)Temperature - Vapor Pressure for EthanolTemperature Vapor Pressure160 °F (71.1 °C) 75.6 kPa170 °F (76.7 °C) 94.9 kPa180 °F (82.2 °C) 118 kPa190 °F (87.8 °C) 146 kPa200 °F (93.3 °C) 179 kPa210 °F (98.9 °C) 218 kPa220 °F (104.4 °C) 263 kPa230 °F (110 °C) 315 kPaTABLE 3

[0162] To the extent that the aging chemical reactions obey first-order kinetics, every 10 °C increase in temperature will halve the aging time. The relative effectiveness of different aging protocols can be estimated by comparison of the severity factors. The severity factor (Ro) is determined using the equation (1):Ro=t*e«T-T°) / 1475))( 1 )where “t” is the aging time in minutes, “T” is the aging temperature (°C), and To is the starting temperature (25 °C). The “normal severity factor” is defined as the severity factor calculated from the time required to age a wet gel material when the wet gel material is heated at a temperature above room temperature (e.g., about 25 C) and below the normal boiling point of the aging fluid at 1 atm pressure.

[0163] The severity factor for a given system can be used to predict the aging time for a wet gel material at any given aging temperature. For a given aging process, the normal severity factor, Ro, can be calculated from equation (1). Using the normal severity factor, the aging time (t) can then be calculated for any given temperature from equation (2):t = Ro / e«T-T°) / 14-75» (2)AAI-100-B-PCT (1197-WOOl)where To is 25 C.

[0164] In an exemplary case, an aging process is traditionally conducted with ethanol as the aging fluid at a temperature of 160 F(71.1 C), pressure of 1 atm, for a time of 840 minutes (14 hours). The normal severity factor can be calculated from equation 1 as shown below:Ro = (840) * e<71 1-25'14'75) = 19,126Based on the normal severity factor calculated above, the aging time at any given temperature for the ethanol aging process can be calculated according to equation 2. Table 4 lists the predicted aging time calculated from the normal severity factor (19,126) for the exemplary ethanol aging process.Calculated Aging Times Using Severity FactorAging Temperature Aging Time160 °F (71.1 °C) 840 minutes170 °F (76.7 °C) 575 minutes180 °F (82.2 °C) 396 minutes190 °F (87.8 °C) 271 minutes200 °F (93.3 °C) 186 minutes210 °F (98.9 °C) 128 minutes220 °F (104.4 °C) 88 minutes230 °F (110 °C) 60 minutesTABLE 4

[0165] The use of a severity factor to estimate aging time for a gel material can allow the aging time to be determined without the need for extended trial and error testing and waste of material. During formation of an aerogel composition, the gel material is heated in an aging fluid for a time sufficient to complete the chemical reactions that form the gel material framework. Once aging is completed the aerogel composition is produced by removing the liquid from the gel material. After drying, the aerogel composition is tested to ensure that the aerogel framework is intact and that the aerogel composition has the desired properties. Until the aerogel is formed, it is difficult to determine whether the aging time was sufficient to produce an aerogelAAI-100-B-PCT (1197-WOOl)composition having the desired properties. To ensure that the aging process is completed, excess aging time is used to complete the process. Once the aging time at normal temperature for the aging fluid is determined, the severity factor can be used to determine the new aging time with confidence that the properties of the resulting aging gel will be satisfactory for the desired performance.

[0166] So, for example, aging at a temperature in accordance with the present disclosure such as at 110 °C requires an aging time of just 60 minutes which provides a clear advantage in terms of elapsed time compared with cooler aging temperatures. However, it must be appreciated in the context of the present disclosure that while 60 minutes at 110 °C is enough to complete aging, the aging process also requires a time for the system to reach the aging temperature, for example starting from room temperature. Therefore, when the present disclosure refers to an aging time of e.g., 5 hours, this may mean a “dynamic aging time” which includes both a ramp-up time to reach the required temperature as well as an “active aging time” at the required temperature. For example, the heat up to 110 °C may take place over 30 minutes, followed by a selected dwell time (active aging time) at 110 °C, then a cool down time of 30 minutes to ambient temperature.

[0167] As part of the aging process, the resulting wet-gel material may be washed in a suitable secondary solvent to replace the primary reaction solvent present in the wet-gel material. Such secondary solvents may be linear monohydric alcohols with 1 or more aliphatic carbon atoms, dihydric alcohols with 2 or more carbon atoms, branched alcohols, cyclic alcohols, alicyclic alcohols, aromatic alcohols, polyhydric alcohols, ethers, ketones, cyclic ethers or their derivative. In a preferred aspect of the disclosure, the initial wet-gel material comprises water or a mixture of ethanol and water. The water from the initial wet-gel material is washed out with ethanol during the aging process.

[0168] As a further part of the aging process, previous methods included the step of adding a hydrophobic agent (e.g., HMDZ) to the aging fluid. The hydrophobic agent reacts with surface silanol groups on the wet gel surface and imparts hydrophobic properties to the finished aerogel or aerogel composite i.e., the resultant aerogel is surface treated by a hydrophobizing agent. However, hydrophobic agent addition may be a disadvantage; it is a further processing step requiring further materials, and moreover excess hydrophobic agent in the finished aerogelAAI-100-B-PCT (1197-WOOl)or aerogel composite is combustible, which is highly undesirable for high temperature uses of the aerogel product, for example the insulation of industrial pipes or structures which may exceed 650 °C in practice. Such excess hydrophobic agent may have to be removed, in previous methods, by an additional annealing step described below. However, the present disclosure avoids the use of added hydrophobic agents and results in products that are inherently hydrophobic and have even better hydrophobic properties than prior art aerogels having added hydrophobic agents.

[0169] Drying

[0170] Once a gel material has been formed and aged, the liquid phase of the gel can then be at least partially extracted from the wet gel using extraction methods to form an aerogel material. Liquid phase extraction, among other factors, plays an important role in engineering the characteristics of aerogels, such as porosity and density, as well as related properties such as thermal conductivity. Generally, aerogels are obtained when a liquid phase is extracted from a gel in a manner that causes low shrinkage to the porous network and framework of the wet gel.

[0171] Aerogels are commonly formed by removing the liquid mobile phase from the gel material at a temperature and pressure near or above the critical point of the liquid mobile phase. Once the critical point is reached (near critical) or surpassed (supercritical) (i.e., pressure and temperature of the system is at or higher than the critical pressure and critical temperature respectively) a new supercritical phase appears in the fluid that is distinct from the liquid or vapor phase. The solvent can then be removed without introducing a liquid-vapor interface, capillary pressure, or any associated mass transfer limitations typically associated with liquid-vapor boundaries. Additionally, the supercritical phase is more miscible with organic solvents in general, thus having the capacity for better extraction. Co-solvents and solvent exchanges are also commonly used to optimize the supercritical fluid drying process.

[0172] One disclosed method of extracting a liquid phase from the wet gel uses supercritical conditions of carbon dioxide, including, for example: first substantially exchanging the primary solvent present in the pore network of the gel with liquid carbon dioxide; and then heating the wet gel (typically in an autoclave) beyond the critical temperature of carbon dioxide (about 31.06 °C) and increasing the pressure of the system to a pressure greater than the critical pressure of carbon dioxide (about 1070 psig). The pressure around the gel material can be slightly fluctuated to facilitate removal of the supercritical carbon dioxide fluid from the gel. CarbonAAI-100-B-PCT (1197-WOOl)dioxide can be recirculated through the extraction system to facilitate the continual removal of the primary solvent from the wet gel. Finally, the temperature and pressure are slowly returned to ambient conditions to produce a dry aerogel material. Carbon dioxide can also be pre-processed into a supercritical state prior to being injected into an extraction chamber.

[0173] Once the aging process is complete, the extraction process is performed in the vessel without removing the aged gel material from the vessel between the aging and extraction steps. After the aging process is complete, an extraction fluid is introduced in the vessel. After introducing the extraction fluid into the aging vessel, the aged gel material is subjected to an extraction process by passing a supercritical fluid through the vessel. The extraction process is conducted at an extraction temperature and an extraction pressure. The extraction temperature and the extraction pressure are greater than the critical temperature and critical pressure of the extraction fluid. For example, if carbon dioxide is used as the extraction fluid, the extraction temperature is maintained above the supercritical temperature of carbon dioxide (31 C) and the extraction pressure is maintained above the supercritical temperature of carbon dioxide (1000 psi).

[0174] As discussed above, the aging process can be conducted at a temperature above the normal boiling point of the aging fluid but at higher than atmospheric pressure, for example in a sealed vessel such that the aging fluid does not boil. To minimize stress that can occur when transitioning from the aging process to the extraction process, the vessel may be maintained at the aging temperature and pressure. For example, in one aspect, at the end of the aging process, the extraction fluid is introduced into the vessel without lowering the temperature of the vessel or reducing the pressure inside the vessel. In another aspect, at the end of the aging process, the temperature and pressure inside the vessel is raised to, or near to, the supercritical conditions of the extraction fluid before the extraction fluid is introduced into the vessel.

[0175] In an aspect of the disclosure, the extraction fluid is introduced into the vessel after the aging process. The temperature and pressure of the extraction fluid entering the vessel may be substantially the same as the aging temperature and the aging pressure. After enough of the extraction fluid is introduced into the vessel, the temperature and pressure inside the vessel are adjusted to maintain the extraction fluid in the supercritical state. In a preferred aspect, theAAI-100-B-PCT (1197-WOOl)extraction fluid is carbon dioxide and the temperature and pressure inside the vessel is maintained at or above the supercritical temperature and pressure of carbon dioxide.

[0176] During extraction of the aging fluid from the aged gel material, the extraction fluid is introduced and removed from the vessel substantially continuously during the extraction process. For example, the extraction fluid can be recirculated through the vessel. If the extraction fluid is recirculated, the recirculation loop may include a separator that removes at least some of the aging fluid from the extraction fluid before the extraction fluid is reintroduced into the vessel. The extraction fluid can be heated outside of the vessel before being reintroduced into the vessel. During extraction, the extraction pressure is maintained above the supercritical pressure of the extraction fluid. Likewise, the extraction temperature is maintained above the supercritical temperature of the extraction fluid. For carbon dioxide extraction processes, the vessel is maintained above the supercritical temperature of carbon dioxide (31 C) and the extraction pressure is maintained above the supercritical temperature of carbon dioxide (1000 psi).

[0177] Like the aging process, it is difficult to determine when the extraction process is complete while the extraction is being performed. Since the extraction process is performed at elevated temperature and pressure, it is difficult and time consuming to obtain a sample for testing. Obtaining a sample would require reducing the temperature and pressure so that the sample can be obtained. Furthermore, if the extraction is not complete, the aged gel material would need to be brought back up to the extraction temperature and pressure. The process of increasing the temperature and pressure to supercritical conditions is a time-consuming process. Also, significant changes in the pressure and temperature within the vessel can place stress on the forming aerogel, possibly damaging the framework of the aerogel. However, the present inventors have found that, using the techniques of the present disclosure, extraction can be achieved in around 1.5 to 2 hours, which is much reduced compared to the 10 hours or so, known from standard aging processes.

[0178] Further details describing the synthesis of aerogels can be found in U. S. Patent Application Publication No. 2016 / 0096949 to Evans et al. and U. S. Patent Application Publication No. 2021 / 03095227 to Evans et al., both of which are incorporated herein by reference.AAI-100-B-PCT (1197-WOOl)

[0179] Aerogel composites

[0180] Aerogel composites of the present disclosure can have a thickness of 15 mm or less, 10 mm or less, 5 mm or less, 3 mm or less, 2 mm or less, or 1 mm or less.

[0181] In an aspect of the present disclosure, the aerogel composite may include an opacifying additive to reduce the radiative component of heat transfer. At any point prior to gel formation, opacifying compounds or precursors thereof may be dispersed into the mixture comprising gel-forming material. Exemplary opacifying additives include, but are not limited to, B4C, Diatomite, Manganese ferrite, MnO, NiO, SnO, Ag2O, EfcCh, TiC, WC, carbon black, titanium oxide, iron titanium oxide, zirconium silicate, zirconium oxide, iron (I) oxide, iron (III) oxide, manganese dioxide, iron titanium oxide (ilmenite), chromium oxide, silicon carbide, or mixtures thereof.

[0182] In some aspects of the disclosure aerogel materials or compositions of the present disclosure are produced in a large scale which requires the use of large-scale extraction vessels. Large scale extraction vessels of the present disclosure can include extraction vessels which have a volume of about 0.1 m3or more, about 0.25 m3or more, about 0.5 m3or more, or about 0.75 m3or more.

[0183] FIG. 1 depicts a schematic diagram of a traditional method of processing a continuous roll of an aerogel. During the formation of the wet gel material, a continuous roll of the fiber support material is used to supply the fiber support material through a loading system. The loading system includes a container for storing the aerogel precursor solution. As the fiber support material is transported through the loading system, the aerogel precursor solution is applied to the fiber support material. The fiber support material is collected in a take up spool after the aerogel precursor solution has been dispensed onto the material. The supported wet gel material is transported to an aging station where it is placed in an aging vessel. The supported gel material is aged in the vessel as described herein. After the aging process is complete, the supported aged gel material is removed from the aging vessel and transported to an extraction vessel The supported aged gel material is extracted as discussed herein. After the extraction process is complete, the resulting supported aerogel is removed from the extractor and transported to a separate area for final processing.AAI-100-B-PCT (1197-WOOl)

[0184] Annealing

[0185] As explained above, in prior art processes a hydrophobic agent such as HMDZ may be added during the aging process to impart hydrophobicity to the finished aerogel or aerogel composition, by surface treatment. For the reasons given above, excess hydrophobic agent is detrimental, being combustible. Therefore, to remove this combustible “fuel” from the finished aerogel composite, aerogels and aerogel compositions in the art were heated, for example at 350 °C in air or at a temperature of 575 to 615 °C in an inert gas such as nitrogen. Prior art practice also revealed that this annealing (or heating) step can enable hydrophobic properties to persist because without annealing, the physical action of water can separate non-covalently bonded hydrophobe from the aerogel, leading to a loss in hydrophobicity.

[0186] The present disclosure does not include the step of adding a further hydrophobic agent during aging, and therefore it is not necessary in the present disclosure to perform an annealing step to drive off excess hydrophobic agent fuel. Nevertheless, the present inventors have found that it may be advantageous to provide a subsequent heating (annealing) step after drying, to improve hydrophobic properties of the obtained aerogel products. This heating may be carried out for example at 350 °C in air or at a temperature of 575 to 615 °C in an inert gas such as nitrogen.

[0187] Aerogel material and composite uses

[0188] The low thermal conductivity of aerogel materials and aerogel composites makes them ideal materials for insulation applications. In one exemplary use, an aerogel composite may be used as a thermal barrier between individual, or groups of, battery cells. Battery cells are susceptible to catastrophic failure under “abuse conditions.” Abuse conditions include mechanical abuse, electrical abuse, and thermal abuse. One or all of these abuse conditions can be initiated externally or internally. For example, service induced stress, aging, errors in design e.g. configurational parameters such as cell spacing, cell interconnecting style, cell form factor, manufacturing, operation, and maintenance are internal mechanical factors that can cause various kinds of abuse. External mechanical factors include damage or injury to a LIB, such as from a fall or from a penetration of the cell. Electrical abuse conditions mainly include internal or external short-circuiting of a battery cell, overcharge, and over discharge. Thermal abuse is typically triggered by overheating. For example, overheating in a battery cell may be caused byAAI-100-B-PCT (1197-WOOl)operating the battery cell under high ambient temperatures. Internally, thermal abuse may be caused by electrical and mechanical defects in the battery cells.

[0189] Battery modules and battery packs can be used to supply electrical energy to a device or vehicles. Device that use battery modules or battery packs include, but are not limited to, a laptop computer, PDA, mobile phone, tag scanner, audio device, video device, display panel, video camera, digital camera, desktop computers military portable computers military phones laser range finders digital communication device, intelligence gathering sensor, electronically integrated apparel, night vision equipment, power tool, calculator, radio, remote controlled appliance, GPS device, handheld and portable television, car starters, flashlights, acoustic devices, portable heating device, portable vacuum cleaner or a portable medical tool. When used in a vehicle, a battery pack can be used for an all-electric vehicle, or in a hybrid vehicle.

[0190] High hydrophobic inorganic precursor material formulations

[0191] The present inventors have developed methods for preparing wet gel materials containing relatively high amounts of at least one hydrophobic inorganic precursor material, such as MTES. As explained above, a known gel precursor having an MTES content of around 33 wt.% or more will result in an intrinsically hydrophobic aerogel without the need for addition of a hydrophobic agent such as TMS in the aging fluid.

[0192] The present inventors also developed wet gel precursor materials having increased amounts of hydrophobic inorganic precursor material, such as having ratios of 50:50 or 70:30 or 90:10 hydrophobic inorganic precursor material to inorganic precursor material (for example MTES: TEOS in a non-limiting example). These proportions of hydrophobic inorganic precursor material are far higher than would typically be used in a wet gel precursor solution. The hydrophobic inorganic precursor material and inorganic precursor material are combined in a single vessel in water and catalyzed by acetic (ethanoic) acid or orthophosphoric acid to produce a sol, for example at a temperature of around 60 °C and for a time of 16-48 hours. Typically, the content of hydrophobic inorganic precursor should be in the amount of above 36 wt.% to 90 wt.% based on the weight of the silica gel precursor materials. Gelation uses ammonia or guanidine as catalyst and takes place over 2 to 240 minutes. The present inventors believe that the high content of hydrophobic precursor leads to a ladder morphology in the wet gel, rather than an amorphous structure at the lower contents, which in turn results in improved resilience of the final aerogel.AAI-100-B-PCT (1197-WOOl)These wet gels may be aged using “standard” conditions as known in the art, for example at 70 °C with ethanol as aging fluid (below the boiling point of ethanol at atmospheric pressure). The inventors found that these materials surprisingly have improved resilience, revealed by compression set testing, compared to known formulations having much lower MTES: TEOS ratios.

[0193] While not being necessary to achieve good mechanical properties, the inventors also found that hot aging in accordance with the disclosed processes described above, such as at temperatures from 90°C to 110 °C, above the boiling point of ethanol (for example) but without boiling, also improves mechanical properties such as resilience.

[0194] Annealing these materials, as disclosed previously, may also improve mechanical properties but a benefit of the high hydrophobic inorganic precursor material formulations is that the annealing step can be eliminated or replaced by a milder (lower temperature) anneal. For example, a 70:30 or 90:10 MTES: TEOS formulation aged at 110 °C and not annealed, can achieve comparable compression set as a known wet gel aged at a standard temperature and having been annealed.Examples

[0195] The following examples are included to demonstrate aspects of the disclosure. It should be appreciated by those of skill in the art that the techniques disclosed in the examples which follow represent techniques discovered by the inventors to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, considering the present disclosure, appreciate that many changes can be made in the specific examples which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.Example 1 (comparative) - low temperature aging

[0196] Sols of both methyltri ethoxysilane (MTES) and poly ethyl silicate are individually prepared via hydrolysis under acidic conditions in ethanol. The ratio and concentration of sol materials are adjusted to obtain a hydrophobe content from MTES of about 32 wt% and to obtain aerogels with about 7 wt% organic content within the aerogel material. Metakaolin isAAI-100-B-PCT (1197-WOOl)incorporated into the combined sol at a weight percentage of at least 0.5% relative to silica content, which is then stirred for no less than 1 hour.

[0197] Lithium hydroxide (1.0 M) is added to the combined sol at concentration sufficient to target aerogel density of about 0.07-0.085 g / cc. The catalyzed sol is cast into a fiber reinforcing phase and allowed to gel. After curing for no greater than 1 h at room temperature, the aerogel materials are aged for about 10 h at 68°C in ethanol aging fluid at an approximate fluidigel ratio of 3: 1. The aged gel is subjected to solvent extraction with supercritical CO2, and then dried for 2 h at 110°C.

[0198] The fiber reinforcing phase is a homogeneous non-woven material comprising textile grade glass fibers (E-glass composition), about 10 mm thick with a density of about 1.5 oz / sq ft. The resulting aerogel material is about 65 wt% aerogel resulting in an expected material density of about 0.16-0.20 g / cc (given a 0.07-0.08 g / cc aerogel density).Example 2 (comparative) - high pressure aging

[0199] A silica-based wet gel composite composed of a wet gel incorporated into a nonwoven fiber reinforcement is obtained as a continuous sheet. The continuous sheet is rolled up onto a support and placed in an aging / extraction vessel. Ethanol is added to the vessel as an aging fluid. The temperature of the ethanol added to the vessel is at 35 °C (95 °F). The heated ethanol is recycled through the vessel during the aging process by continuously removing ethanol from the vessel while continuously adding ethanol to the vessel.

[0200] After introducing the heated ethanol into the vessel, the aging pressure inside the vessel is raised to an aging pressure of 1100 psi (7,584 kPa), initiating the aging process. During the aging process the temperature of the ethanol inside the vessel is raised to 98.9 °C (210 F). Additionally, during the aging process the pressure can increase up to about 1500 psi (10,342 kPa). The aging process is run for approximately 130 minutes.

[0201] When the aging process is complete, the extraction process is initiated. The aged gel is subjected to solvent extraction with supercritical CO2.AAI-100-B-PCT (1197-WOOl)Example 3 - high temperature aging

[0202] A silica-based wet gel composite composed of a wet gel incorporated into a nonwoven fiber reinforcement is obtained as either a continuous sheet, a coupon, or a stack. The composite is placed in a closeable aging / extraction vessel. Ethanol is added to the vessel as an aging fluid.

[0203] After introducing the ethanol into the vessel, the temperature is raised to 110 °C. The pressure inside the vessel is not externally raised but increases to around 50 psi (345 kPa) due to increased vapor pressure of the heated ethanol. The aging process is run for approximately 130 minutes. When the aging process is complete, the extraction process is initiated. The aged gel is subjected to solvent extraction with supercritical CO2.Example 4 - improved mechanical properties of wet gel

[0204] Figure 2 illustrates improved resilience (reduced permanent deformation) in a material of the present disclosure aged at higher temperature of 16 hours in static compression set testing according to ASTM D3574-17 Sect. 42.1.2. In the context of the present disclosure, “compression set” refers to the percentage of an applied strain that remains in a sample after the applied strain is released and the sample is allowed to recover for a specified period of time. Compression set testing was carried out using bespoke testing rigs using 4”x4” coupons having a thickness (TKS) of 2.5 mm. The samples were placed in between two stainless steel plates and compressed down to desired thickness / strain by placing a spacer in between the two plates. Then the desired thickness / strain was locked by fixing the bolts going through the two plates. After 24 hours holding time at desired thickness / strain (in Figure 2, it is 50%, the maximum strain having been determined using a sacrificial sample), the plates were removed from the samples and the samples were allowed to recover for 24 hours before measuring thickness of the samples. The resulting compression set was calculated as: (Initial TKS - TKS after recovery ) / (Initial TKS * targeted compressive strain)* 100. The left axis of Figure 2 shows in % the resulting compression set in the samples after testing, with a lower value indicating less compression and therefore improved resilience. The materials aged at higher temperature have better resilience than the materials aged at lower temperature i.e., reduced plastic deformation, with increasing elasticity for a given stress as aging temperature increases.AAI-100-B-PCT (1197-WOOl)

[0205] Figure 3 shows the results of cyclic stress testing. The sample size was 2 inch circles with thickness of 5 mm, tested on a Mechanical tester Mark 10, Fl 505. Firstly, the samples are compressed to target maximum observed strain of 60% and then backed off to 50% strain, repeated for 50 cycles. After compression, the thickness of samples were immediately measured and also measured after full recovery, and compression set was calculated in the same way as in Figure 10. The experimental protocol therefore used the following steps:• Step 0: Pre-load at 0.2 psi, report starting thickness• Step 1: Strain sample at 2 mm / min to 60% strain• Step 2: Hold for 10 minutes• Step 3: Unload to 50% strain at 2 mm / min• Step 4: Hold at 50% strain for 10 minutes• Step 5: Load to 60% strain at 2 mm / min• Step 6: Repeat steps 2-5 (50 times)• Step 7: Report immediate 0.2 psi thickness• Step 8: Recover for 24 hours, remeasure / report thickness at 0.2psi.

[0206] Minimum stress after 50x cycles were also recorded on the right y axis. The samples become significantly more resilient (with lower compression set) and more rigid (with greater min compressive stress at 50% strain) at the same time when hot aging temperature is increased.

[0207] Figures 4A and 4B demonstrate the improvement in resilience, evidenced by static and cyclic compression set tests on hot aged at 90 °C and standard aged at 68 °C composites, before annealing (“Standard”) and after annealing at 350 °C (shown in the figures as “AAA”). All compression set testing herein is performed as described earlier, with different amounts of strain and cycles as described in the individual figures. Overall, the hot aged samples have improved compression set compared with standard aging even when not annealed, and annealing further improves compression set. Notably for the hot aged sample in cycle testing the compression set is much improved compared to the standard sample.

[0208] Figures 5A to 5C show the effect of annealing temperature on compression set. Each bar chart shows different anneal temperatures (and no annealing) for a 5mm sample of 110 °C aged composite. Chart (A) with 60% strain and 20 minute hold shows the marked differenceAAI-100-B-PCT (1197-WOOl)between annealed and non-annealed samples, the annealed samples having far improved compression set. Chart (B) with a 50x cyclic test shows the improvement in compression set associated with increasing anneal temperature. Chart (C) at 80% strain shows the improvement due to increased anneal temperature.Example 5 - high MTES formulations

[0209] This example relates to the aspects described above having a relatively high ratio of MTES to TEOS, namely 70-90 % MTES with formation of the sol in a single pot with water and catalyzed by acetic (ethanoic) acid. For comparison, previous formulations in the art (described in this Example as “standard”) may have around 36 % MTES content in the silica gel precursor materials. In this example, the wet gels were prepared by combining MTES (241.2 g, 1.353 mol) with TEOS (108.6 g, 0.521 mol) in water (115 g, 6.389 mol) and acetic acid (0.437 g, 0.00728 mol). The solution is stirred at 60 °C for at least 16 hours, to produce a sol having a ratio of the weight contribution of hydrolysis product of hydrophobic gel precursor (MTES) to the total weight contribution of all solids after hydrolysis of 70:30. The sol is then caused to gel and is cast into a reinforcing material as described above, followed by aging, extraction and optional annealing, also as herein described.

[0210] Figure 6A illustrates a standard sample (36 % MTES) that was aged by a standard procedure (not hot aged) and then annealed at 350 °C. Once again, the annealing has a clear beneficial effect on compression set. Figure 6B illustrates a sample having 70% MTES relative to TEOS, aged again as standard at 70 °C. The compression set results are all improved as compared with Figure 6A having lower MTES, even without annealing, but there is a marked improvement when comparing the annealed samples too. 17.2 % strain remains for 36 % MTES after annealing at 350 °C whereas 6.9 % strain remains for 70 % MTES, for the same annealing at 350 °C and standard aging at 70 °C.

[0211] Figure 6C illustrates compression set for samples containing 90% MTES and additionally aged at 110 °C in accordance with the hot aging procedures of the present disclosure. Here it can be seen that even without annealing, the hot aged sample achieved the same compression set (around 17 %) as the standard, 36 % MTES sample with standard aging and annealed at 350 °C. This compression set can be further improved with an additional annealing step. These data demonstrate how the high-MTES precursors allow for low temperatureAAI-100-B-PCT (1197-WOOl)annealing or even elimination of the annealing step, while achieving adequate compression set results. While the example here is a 90: 10 MTES: TEOS formulation, further experiments suggest that the need for annealing can also be removed for formulations having a 70:30 ratio when aged at 110 °C.

[0212] Figures 7A to 7C show compression set data across three different silica densities, all aged at 70 °C, with different proportions of MTES shown in the formulation (e.g. 70:30) and different annealing temperatures. In these and in all subsequent examples, as well as in the entire specification, “silica density” refers to the mass of solid silica material per unit volume of cast fluid, i.e. in g / cc (gram per cubic centimeter). In all cases the higher MTES formulations show better resiliency, demonstrated by lower final compression set, especially after annealing, with further improvements as silica density is increased. The compression set testing here was carried out at 60 % strain with a 20-minute hold, and final recoveries are illustrated.

[0213] Figures 8A to 8C show compression set data across three different silica densities, all aged at 110 °C, with different proportions of MTES shown in the formulation (e.g. 70:30) and different annealing temperatures. In all cases the higher MTES formulations show better resiliency, especially after annealing, with further improvements as silica density is increased. The compression set testing here was carried out at 60 % strain with a 20-minute hold, and final recoveries are illustrated. Moreover, a comparison of standard aging in Figure 7 with the hot aging of Figure 8 shows a further clear improvement in compression set. In fact, it can be seen that excellent compression set behavior is demonstrated through 110 °C aging, even without an anneal step. Purely by way of example, comparing the 0.065 g / cc silica density samples of Figures 7B and 7C reveals that for a 70:30 MTES formulation, equivalent compression set can be obtained with 110 °C aging without an anneal step, as with 70 °C aging plus an anneal step.

[0214] Figure 9 illustrates corresponding improvements as with Figures 8A to 8C, but here performed at 80% strain. Even in this extremely aggressive testing, all hot aged samples performed extremely well, particularly when MTES was 90% of the precursor materials. The compression set in this case is very good even with no anneal, but a further anneal step only improves the results.

[0215] Figure 9 shows the pore size difference between a high MTES sample aged at either 70 °C or 110 °C.AAI-100-B-PCT (1197-WOOl)

[0216] Figures 10A and 10B are SEM images of aerogels after compression set testing under 50% strain and 24 hours hold. Figure 10A is a standard aerogel (low MTES) and has a compression set of 40%, whereas Figure 10B is a high MTES analog, with only 8% compression set, and therefore much more resilient. Comparison of the images shows that the high MTES aerogel has increased heterogeneity of pore and particle sizes.

[0217] Figures 11A and 11B demonstrate several advantages of high MTEs aerogels; in these figures, the standard aerogels contain 36% hydrophobe whereas the high MTES aerogels contain 74% hydrophobe. From Figure 11A it can be seen that with annealing, the high MTES formulations show much improved compression set (7%) tested at 50% strain for 24 hours, than the standard aerogel (24%) at regular 68 °C aging. When the same samples are hot aged, compression set improves for both standard and high MTES but the high MTES variant shows an even more improved compression set of 4% versus 9% for the standard chemistry.

[0218] Figure 11B shows corresponding testing for non-annealed samples. For regular aging at 68 °C the high MTES sample shows slightly improved compression set compared with standard chemistry. However, the difference is marked when the samples are hot aged (and not annealed); the high MTES formulation achieves a compression set of just 7% which is the same as the high MTES sample with 68 °C aging and annealing in Figure 11B. On the other hand the standard chemistry when hot aged (but not annealed) has a much higher compression set of 70%. These figures therefore demonstrate that with the high MTES formulations, improved compression set can be achieved either by annealing or by hot aging and not annealing. In other words the high MTES chemistry allows the anneal step to be eliminated, when hot aging is used.

[0219] Figures 12A, 12B and 12C show compression set after 24 hours for both standard chemistry (36% hydrophobe) and high MTES (70:30 MTES: TEOS), with annealing and different temperatures (or no anneal) for different silica densities - all with aging at 68 °C. The trend is clear that the high MTES formulations always show better compression set and that the annealed 70:30 samples show excellent compression set compared with standard chemistry.

[0220] Figures 13A, 13B and 13C show data equivalent to Figures 12A, 12B and 12C but for samples that were aged at 110 °C. The same trends are evident as the samples aged at 68 °C but additional to note is that with a silica density of 0.085 g / cc even the non-annealed samples reach a low compression set value which is close to the annealed samples. Again, this shows howAAI-100-B-PCT (1197-WOOl)the high MTES formulation, combined with a hot aging process, can eliminate the need for an energy-intensive anneal.

[0221] Figures 14A and 14B show compression set for samples (both annealed and nonannealed) of high MTES formulations with a 90:10 MTES: TEOS ratio, for different amounts of water as solvent in the precursor solution of the sol. Figure 14A is for aging at 68 °C and shows no particular pattern as the water percentage changes. Figure 14B shows equivalent data for aging at 80 °C. Here it can be seen that for lower amounts of water the compression set is much improved. Even non-annealed samples achieve adequate compression set. This again shows that a high-MTES chemistry with hot aging leads to improved compression set, and also that a lower amount of water in the precursor solution further improves resiliency.

[0222] Figures 15A and 15B show compression set for high MTES formulations having 70:30 MTES: TEOS, tested at 50% strain and 24 hours hold, as a function of different concentrations of acetic acid used as hydrolysis catalyst, “lx” relates to a standard concentration of acid, being 14.5 mM and “2x” is twice that concentration, and so on. Both sets of data relate to annealed samples. For both silica densities there is a clear improvement in compression set for increasing acid concentration. Figure 15B shows a clear improvement in compression set for increased silica density of 0.065 g / cc as compared with Figure 15A with a silica density of 0.040 g / cc.

[0223] Figure 16A shows thermal conductivity measured for high MTES formulation aerogels having either 70:30 or 90: 10 MTES: TEOS, against different anneal temperatures (or no anneal). Even without annealing, or with a low temperature anneal, the 70:30 formulation has extremely low thermal conductivity.

[0224] Figure 16B shows compression set data for the same samples. The best compression set is achieved by the 90:30 formulation.

[0225] Cyclic compression testing was also performed on standard chemistry and high MTES chemistry samples, for 400 cycles at 50% strain. All samples were hot aged at 110 °C and contained a fiber reinforcement. For the normal chemistry (36% MTES) samples, the following results were obtained:AAI-100-B-PCT (1197-WOOl)Initial Density, Final Density, g / cc % CFD Compression g / cc (% densification) Area Loss Set (%) 0.160 0.275 (71.4) 42.9 68.5TABLE 5

[0226] For the high MTES equivalent the following results were obtained:Initial Density, Final Density, g / cc % CFD Compression g / cc (% densification) Area Loss Set (%) 0.168 0.191 (13.1) 24.3 18.9TABLE 6

[0227] It is clear that the high MTES formulation results in much improved mechanical properties in terms of vastly improved compression set and densification. The high MTES aerogels are highly resilient.Conclusions

[0228] The inventors of this application have developed the disclosed methods, having -among others - the following advantages as compared with standard temperature aging:• Shorter aging time;• Ability to bulk-age rolls of fiber-reinforced aerogel materials, in industrial quantities; • Avoidance of externally-applied pressure during aging;• Ability to perform the aging and extracting steps in the same vessel;• Possibility to avoid a subsequent heating (annealing) step, though annealing may lead to even more improved products;• Avoiding the requirement to remove lower-boiling point solvents prior to aging (as would be the case for aging with water).• Avoiding the need to add further monomer to the aging solution.AAI-100-B-PCT (1197-WOOl)• Production of a stiffer (more resilient) wet gel which is easier to process.• Avoidance of adding further hydrophobic agents in a post-treatment, and yet still achieving aerogels with excellent intrinsic hydrophobicity.

[0229] Aerogel compositions and composites prepared according to the disclosed methods possess at least one of the following improvements as compared with analogous materials prepared by standard lower-temperature aging:• Improved heat of combustion;• Lower water uptake - even without the requirement for an annealing step, though annealing may improve this property even further;• Improved hydrophobicity despite a hydrophobic organic content which may be lower than prior art values e.g. lower than 33%;• Lower density;• Improved resilience, demonstrated by lower compression set - even without the requirement for an annealing step, though annealing may improve this property even further.

[0230] While the benefits of the presently disclosed process have been described herein with reference to particular reinforced aerogels, the present inventors believe that the disclosed methods are applicable to a range of aerogel compositions, organic and inorganic, spanning different ratios of the MTES and TEOS precursors described, and even to other precursors, catalysts and aging solutions. In this regard the skilled person understands that the “hot aging” described herein may be generally applicable to aerogel synthesis without particular limitation, and would be expected to achieve the benefits described herein.

[0231] In this patent, certain U. S. patents, U. S. patent applications, and other materials (e g., articles) have been incorporated by reference. The text of such U. S. patents, U. S. patent applications, and other materials is, however, only incorporated by reference to the extent that no conflict exists between such text and the other statements and drawings set forth herein. In the event of such conflict, then any such conflicting text in such incorporated by reference U. S.AAI-100-B-PCT (1197-WOOl)patents, U. S. patent applications, and other materials is specifically not incorporated by reference in this patent.

[0232] Further modifications and alternative aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.

[0233] When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. The invention comprises, consists of or consists essentially of the disclosed and claimed features, in which the phrase “consists essentially of’ or the like excludes the presence of further features if such features materially affect the working of the invention.

[0234] The invention may also broadly consist in the parts, elements, steps, examples and / or features referred to or indicated in the specification individually or collectively in any and all combinations of two or more said parts, elements, steps, examples and / or features. In particular, one or more features in any of the embodiments, examples and aspects described herein may be combined with one or more features from any other embodiments, examples and aspects described herein.

[0235] Protection may be sought for any features disclosed in any one or more published documents referenced herein in combination with the present disclosure.

[0236] Although certain example embodiments of the invention have been described, the scope of the appended claims is not intended to be limited solely to these embodiments. The claims are to be construed literally, purposively, and / or to encompass equivalents.

Claims

AAI-100-B-PCT (1197-WOOl)WHAT IS CLAIMED IS:

1. A method of preparing a wet gel material comprising:providing a precursor solution comprising silica gel precursor materials and a solvent, wherein the silica gel precursor materials comprise more than about 36 wt.% of at least one hydrophobic inorganic precursor material; andallowing the silica gel precursor materials in the precursor solution to transition into a wet gel material, wherein the wet gel material comprises a silica-based framework and the solvent.

2. The method of claim 1, wherein the silica gel precursor materials comprise up to about 90 wt.%, or about 40-80 wt.%, or about 50-70 wt.% of the at least one hydrophobic inorganic precursor material.

3. The method of claim 1 or claim 2, wherein the at least one hydrophobic inorganic precursor material is selected from the group consisting of trimethyl methoxy silane [TMS], dimethyl dimethoxysilane [DMS], methyl trimethoxysilane [MTMS], trimethyl ethoxysilane, dimethyl diethoxysilane [DMDES], methyl triethoxysilane [MTES], ethyl triethoxysilane [ETES], diethyl diethoxysilane, ethyl triethoxysilane, propyl trimethoxysilane, propyl triethoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane [PhTES], hexamethyldisilazane and hexaethyldisilazane, and combinations thereof.

4. The method of any preceding claim, wherein the silica gel precursor materials further comprise at least one inorganic precursor material selected from: metal silicates such as sodium silicate or potassium silicate; alkoxysilanes such as tetraethoxysilane (TEOS), tetramethoxysilane (TMOS), and tetra-n-propoxysilane; partially hydrolyzed alkoxysilanes such as partially hydrolyzed TEOS and partially hydrolyzed TMOS; condensed polymers of alkoxysilanes such as condensed polymers of TEOS and condensed polymers of TMOS; alkylalkoxy silanes, and combinations thereof.AAI-100-B-PCT (1197-WOOl)5. The method of any preceding claim, wherein the silica gel precursor materials comprise at least one inorganic precursor material and wherein the ratio of hydrophobic inorganic precursor material to inorganic precursor material is about 50:50 or 70:30 or 90: 10.

6. The method of claim 5, wherein the hydrophobic inorganic precursor material comprises or consists of MTES and wherein the inorganic precursor material comprises or consists of TEOS.

7. The method of any preceding claim wherein the solvent is water and wherein the step of allowing the silica gel precursor materials in the precursor solution to transition into a wet gel material comprises combining the silica gel precursor materials in a single vessel in the water and catalysing with an acid to produce a wet gel.

8. The method of claim 7 wherein the acid is ethanoic (acetic) acid or orthophosphoric acid.

9. The method of claim 7 or claim 8 wherein the acid has a concentration in the precursor solution of about 5 mM to about 150 mM, or about 20 mM to about 120 mM, or about 50 mM to about 100 mM, or about 45 mM to about 120 mM.

10. The method of any of claims 7 to 9 wherein the molar ratio of hydrophobic inorganic precursor material to acid in the precursor solution is about 10:1 to 200: 1, or about 10:1 to 100:1, or about 20:1 to 50:1, or 10:1 to 50:1.

11. The method of any preceding claim wherein the solvent is present in an amount of 10-30 %, 15-25 % or 18-22 % by volume of the precursor solution, preferably wherein the solvent is water.

12. The method of any preceding claim, further comprising:placing the wet gel material in a vessel;introducing an aging fluid into the vessel; andAAI-100-B-PCT (1197-WOOl)aging the wet gel material by heating the wet gel material and the aging fluid at an aging temperature and an aging pressure.

13. The method of claim 12, wherein the aging temperature is below the normal boiling point of the aging fluid at atmospheric pressure.

14. The method of claim 12, wherein the aging temperature is below the boiling point of the aging fluid at the aging pressure and the aging pressure is greater than atmospheric pressure.

15. The method of any of claims 12 to 14, wherein the aging fluid comprises, consists of or consists essentially of ethanol or methanol.

16. The method of any of claims 12 to 15, wherein the aging pressure of the vessel is maintained without the application of external pressure.

17. The method of any of claims 12 to 16 wherein the vessel contains a headspace and the aging pressure is provided by compressing gas present in the headspace.

18. The method of any of claims 12 to 17 wherein the aging pressure is provided by compressing by introducing aging fluid into the closed vessel.

19. The method of any of claims 12 to 18, wherein the wet gel material and aging fluid are heated to an aging temperature of between about 80 C and about 130 C during aging of the wet gel material.

20. The method of any one of claims any of claims 12 to 19, wherein the wet gel material and aging fluid are heated to an aging temperature of between about 95 °C and about 120 °C, or about 100 °C and about 115 °C, or about 110 °C, or about 90 to 100 °C and preferably about 95 °C during aging of the wet gel material.AAI-100-B-PCT (1197-WOOl)21. The method of any one of claims any of claims 12 to 20, wherein the wet gel material is aged for a time between about 1 hour and about 24 hours, optionally wherein the wet gel material is aged for a time between about 2 hours and about 15 hours or 5 hours and 22 hours, or between about 10 hours and 20 hours, and preferably about 16 hours.

22. The method of claim 21 wherein the wet gel material is aged for a time which comprises a heating up from ambient temperature time, an active aging time and a cooling down to ambient temperature time, wherein the active aging time is from about 30 minutes to about 4 hours, preferably about 1 to about 2 hours, and optionally about 1 hour, and optionally wherein the heating up and cooling down times are up to one hour, preferably about 30 minutes.

23. The method of any of claims 12 to 22, wherein the wet gel material is aged for a time determined from the aging temperature and the normal severity factor.

24. The method of any one of claims 12 to 22, wherein during aging of the wet gel material, aging fluid is removed and aging fluid is introduced substantially continuously.

25. The method of any one of claims 12 to 24, further comprising washing the wet gel material with the aging fluid prior to heating the wet gel material, wherein the aging fluid removes and replaces at least a portion of a liquid present in the wet gel material.

26. The method of any preceding claim, wherein the wet gel material comprises a reinforcement material.

27. The method of claim 26, wherein the reinforcement material is in the form of a continuous sheet.

28. The method of any preceding claim wherein no hydrophobizing agent is added to the wet gel material.AAI-100-B-PCT (1197-WOOl)29. The method of any preceding claim, further comprising extracting a liquid phase from the wet gel material, preferably using supercritical carbon dioxide, and preferably wherein the step of extracting a liquid phase takes place in the same vessel as the aging step.

30. The method of any preceding claim which does not further comprise any subsequent heating step.

31. The method of any one of claims 1 to 29, further comprising a subsequent heating step.

32. The method of claim 31, wherein the subsequent heating step is performed at a temperature of around 300 to 400 °C and preferably around 350 °C in air or at a temperature of 575 to 615 °C in an inert gas such as nitrogen.

33. An aerogel composition comprising a silica-based aerogel obtainable by the method of any of claims 29 to 32.

34. The aerogel composition of claim 33 wherein the silica-based aerogel is not surface treated by a hydrophobizing agent.

35. The aerogel composition of any of claims 33 to 34 wherein the silica-based aerogel has a thermal conductivity of about 20 mW / M*K or less and preferably about 17 mW / M*K or less.

36. An aerogel composition according to any of claims 33 to 35 comprising a reinforcement material wherein the reinforcement material preferably comprises a fiber reinforcement material or a foam reinforcement material.

37. An aerogel composition according to claim 36, having a compression set of less than around 12 %, less than around 10 % or less than around 8 % when held with a compressive strain of around 50% in a test according to ASTM D3574-17 Sect. 42.1.2.AAI-100-B-PCT (1197-WOOl)38. An aerogel composition according to claim 36 or claim 37, having a compression set of less than around 60 %, less than around 40 % or less than around 30 % when compressed to 60 % of targeted strain reduced to 50% strain, and repeated for 50 cycles.

39. An aerogel composition according to any of claims 33 to 38 having a silica density of 0.020 to 0.100 g / cc, 0.030 g / cc to 0.090 g / cc, 0.050 to 0.090 g / cc or 0.075 to 0.100 g / cc.

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