Hollow fiber membranes having polydiorganosiloxane polyoxamide copolymer skin layers and methods for making and using same

Abstract

The present invention relates to hollow fiber membranes, membrane contactors, and related methods of production and use. The asymmetric hollow fiber membrane comprises a porous substrate having a multitude of pores and comprising at least one semi-crystalline thermoplastic polyolefin (co)polymer. A skin layer comprising at least one polydiorganosiloxane polyoxamide copolymer covers the porous substrate. The skin layer is less porous than the porous substrate and forms the outer surface of the asymmetric hollow fiber membrane, while the porous substrate constitutes the inner surface of the hollow fiber membrane. The skin layer is preferably non-porous.

Description

[Technical field]

[0001] The present disclosure relates to hollow fiber membranes and gas separation articles made using such hollow fiber membranes, as well as methods of making and using such hollow fiber membranes and gas separation articles. [Background technology]

[0002] Microporous hollow fibers can be used to separate components from fluid streams based on size, phase, charge, etc. Microporous hollow fibers often employ materials with controlled porosity and pore size, often on the order of a few micrometers, and can have many uses, including, for example, separation, filtration, diffusion, and barrier applications. These broad applications have practical applications in medical devices, electrochemical devices, chemical processing devices, pharmaceutical equipment, and water purification, to name a few. Summary of the Invention

[0003] The functionality of microporous hollow fiber membranes is often a complex function of the specific end use, the structure of the hollow fiber (e.g., hollow fiber diameter, wall thickness, porosity, pore size, and pore tortuosity), and the composition or chemistry of the asymmetric hollow fiber membrane surface. Often, these and other variables of the hollow fiber must be tailored to the specific end use. For example, membranes with gas-permeable separation layers can be used to provide selective gas / gas and / or gas / liquid passages.

[0004] Asymmetric microporous hollow fiber membranes allow the selective passage of dissolved gases and the blocking of liquid water or other aqueous liquids and may be advantageously used in membrane contactors to achieve gas / liquid separations in certain applications such as degassing of aqueous printing inks during printing, or separation of dissolved gases such as carbon dioxide or methane from aqueous brines used to enhance oil recovery.

[0005] Membrane contactors useful for gas / liquid separation applications can be advantageously manufactured using hydrophobic asymmetric microporous hollow fiber membranes. Because the membrane is hydrophobic and has very small pores, liquids do not easily pass through the pores and are retained on the membrane surface on the inside or outside of the hollow fiber membrane. The hydrophobic hollow fiber membrane surface acts to separate the gas phase from the liquid phase without dispersing it. Such membrane contactors can be advantageously used to selectively separate gases such as air, carbon dioxide, or methane from aqueous liquids such as water or aqueous brine.

[0006] At least certain known microporous hollow fiber membranes have been found to be less than entirely satisfactory in some particular gas / liquid separation applications under certain operating conditions. Thus, a need exists for improved hollow fiber membrane contactors having improved design or operating characteristics over known membrane contactors designed for particular end uses.

[0007] For example, given environmental concerns, the desire to separate components, the need to protect equipment, and / or efforts to improve process efficiency, it is often necessary or desirable to remove one or more components or contaminants from an effluent stream, e.g., so that the components or contaminants do not pollute the environment, adversely affect equipment, or so that they can be recycled. Existing industrial processes frequently must be upgraded to reduce environmental emissions and / or to increase efficiency. Thus, there is often a need for processes and systems that can be economically retrofitted to existing plants to reduce emissions, protect equipment, recycle, or improve efficiency.

[0008] Thus, there is also a need for improved microporous hollow fiber membrane materials that can be used in a wider range of applications and that can perform better for specific purposes, under specific operating conditions, etc. There is also a need for improved membrane contactors having improved designs or properties over known membrane contactors for use in gas / liquid separations in specific applications, such as degassing aqueous printing inks during printing, or separating dissolved gases such as carbon dioxide or methane from aqueous brines used to enhance oil recovery. It is an object of at least certain exemplary embodiments of the present disclosure to provide asymmetric microporous hollow fiber membrane devices that meet these and other needs.

[0009] Briefly, in one aspect, the present disclosure describes an asymmetric hollow fiber membrane comprising a porous substrate having a multiplicity of pores and a skin layer overlaying the porous substrate. The porous substrate comprises at least one semi-crystalline thermoplastic polyolefin (co)polymer, and the skin layer comprises at least two repeating units of formula I: [ka] [In the formula, Each R 1 is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is the formula R 3 HN-G-NHR 3 Two from -NHR 3 is a divalent residue equivalent to a diamine excluding the R 3 is hydrogen or alkyl, or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; q is an integer equal to or greater than 1. The composition comprises at least one polydiorganosiloxane polyoxamide copolymer comprising:

[0010] Preferably, n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer. In such embodiments, n, p, and q are selected such that the polydiorganosiloxane blocks comprise up to 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer.

[0011] The semi-crystalline thermoplastic polyolefin (co)polymer is derived by polymerizing one or more branched or linear alpha-olefin monomers selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, or combinations thereof. The semi-crystalline thermoplastic polyolefin (co)polymer preferably comprises polyethylene, polypropylene, or combinations thereof, and more preferably the polyolefin (co)polymer consists of or essentially consists of polypropylene.

[0012] In certain currently preferred embodiments, the multiplicity of pores comprises micropores. In some exemplary embodiments, the micropores have a diameter between 0.01 micrometers and 1.0 micrometers. In other embodiments, the micropores have a diameter between 0.02 micrometers and 0.5 micrometers. In further exemplary embodiments, the asymmetric hollow fiber membrane exhibits a porosity between 5% and 80%. In other embodiments, the asymmetric hollow fiber membrane exhibits a porosity between 10% and 50%.

[0013] In another aspect, the present disclosure describes a separation article comprising a plurality of asymmetric hollow fiber membranes according to any of the preceding embodiments. In some exemplary embodiments, the plurality of asymmetric hollow fiber membranes are arranged in an array, which may be formed by braiding. Optionally, the array is pleated, folded, or rolled to form a cylinder or cassette.

[0014] In a further exemplary embodiment, the separation article is 2 or CH 4 More than CO 2 Preferably, the separation article is selectively permeable to at least 8, 2 / N 2 In another exemplary embodiment, the filtration article exhibits selectivity. 2 More than O 2 It is selectively permeable to

[0015] In a further aspect, the disclosure describes a method of using any of the aforementioned separation articles, where the separation article is used to separate a gas phase from a liquid phase. In some embodiments, the gas phase is N 2 , O 2 , CO 2 , C.H. 4or a combination thereof. In certain embodiments, the gas phase comprises water vapor. In such embodiments, the separation article may be useful in humidifying or dehumidifying the gas phase. In certain embodiments, the gas phase comprises one or more volatile organic compounds. In such embodiments, the separation article may be useful in removing volatile organic compounds from either the gas phase or the liquid phase.

[0016] In some embodiments, the liquid phase comprises liquid water. Optionally, the liquid phase is an aqueous printing ink or an aqueous brine. In some embodiments, the liquid phase comprises one or more organic compounds. For example, the liquid phase may contain one or more organic alcohols, ketones, ethers, esters, or hydrocarbon solvents. In some such embodiments, the liquid phase may comprise one or more surfactants. For example, the liquid phase may comprise one or more nonionic, anionic, cationic, or amphoteric surfactants.

[0017] In a final aspect, the disclosure describes a method of making an asymmetric hollow fiber membrane comprising providing at least one substrate resin and at least one skin layer resin, co-extruding the substrate resin and the skin layer resin to form an asymmetric hollow fiber membrane precursor, and stretching the asymmetric hollow fiber membrane precursor to form an asymmetric hollow fiber membrane having a skin layer made from the skin layer resin covering a porous substrate made from the substrate resin and having a multiplicity of pores.

[0018] The substrate resin comprises at least one semi-crystalline thermoplastic polyolefin (co)polymer and the skin layer comprises at least two repeating units of formula I: [ka] [In the formula, Each R 1 is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is the formula R 3HN-G-NHR 3 Two from -NHR 3 is a divalent residue equivalent to a diamine excluding the R 3 is hydrogen or alkyl, or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; q is an integer equal to or greater than 1. The polydiorganosiloxane polyoxamide copolymer comprises

[0019] Preferably, n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer. In such embodiments, n, p, and q are selected such that the polydiorganosiloxane blocks comprise no more than 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer.

[0020] The semi-crystalline thermoplastic polyolefin (co)polymer is derived by polymerizing one or more branched or linear alpha-olefin monomers selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, or combinations thereof. The semi-crystalline thermoplastic polyolefin (co)polymer preferably comprises polyethylene, polypropylene, or combinations thereof, and more preferably the polyolefin (co)polymer consists of or essentially consists of polypropylene.

[0021] In some exemplary embodiments, the skin layer resin is substantially free of any pore-forming material in an amount effective to cause pore formation, hi some such embodiments, co-extruding the substrate resin and the skin layer resin to form the asymmetric hollow fiber membrane precursor comprises co-extruding the substrate resin and the skin layer resin through an annular co-extrusion die to form the asymmetric hollow fiber membrane precursor.

[0022] In some embodiments, the skin layer forms the inner lumen of the hollow fiber. In certain embodiments, the skin layer is disposed between two substrate layers.

[0023] In certain exemplary embodiments, the method further comprises annealing the asymmetric hollow fiber membrane precursor. Preferably, annealing the asymmetric hollow fiber membrane precursor comprises annealing the asymmetric hollow fiber membrane precursor prior to stretching the asymmetric hollow fiber membrane precursor.

[0024] In some exemplary embodiments, the method further includes treating the asymmetric hollow fiber membrane precursor by exposing the PDSP copolymer skin to actinic radiation, e.g., ultraviolet, visible or infrared radiation, or to ionizing radiation, e.g., electron beam radiation, or gamma radiation, to optionally react with one or more radiation curable materials and / or chemically crosslink the PDSP copolymer.

[0025] Exemplary embodiments of the present disclosure may provide a variety of unexpected results and advantages. One such advantage of certain exemplary embodiments of the present disclosure is that asymmetric hollow fiber membranes provide significantly higher gas flux and higher CO2 output than other types of membranes. 2 / N 2 The exemplary hollow fiber membrane according to the present disclosure can achieve both high selectivity and low CO2 emissions up to 784 GPU. 2 Excellent gas transmission rate and CO2 resistance up to 11.2 2 / N 2 This gas permeability is 80 to 100 times higher than that of known poly(4-methyl-1-pentene) (PMP) thermally induced phase separation (TIPS) hollow fiber membranes. The asymmetric hollow fiber membranes of the present disclosure may also exhibit uniform pore size and high porosity compared to other types of membranes.

[0026] Hollow fibers also have high CO 2 / N 2 The fibers exhibit good skin integrity as indicated by the selectivity. It is also very surprising that no delamination is observed between the polydiorganosiloxane polyoxamide (PDSP) copolymer skin layer and the polyolefin (e.g., polypropylene, PP) substrate layer after hot drawing. The fibers exhibit good mechanical strength and are easily handled in the post-extrusion drawing process used to form the porous hollow fibers.

[0027] In addition, SEM images show that the thickness of the PDSP skin layer after stretching can be as low as 2.6 μm, which is in stark contrast to hollow fiber membranes made with silicone skin layers, which typically exhibit wall thicknesses of greater than 30 μm.

[0028] Additionally, polydiorganosiloxane polyoxamide (PDSP) copolymers are thermally stable to temperatures above 300° C. due to the oxamide linkages which distinguish them from other silicone thermoplastic elastomers (TPEs) such as silicone polyureas (SPUs), which are less stable at temperatures above 200° C. Such high thermal stability adds to the processing conditions resistance of substrate layer materials such as PP at processing temperatures up to 220° C.

[0029] Additionally, exemplary hollow fiber membranes according to the present disclosure may exhibit the following advantages: 1) Due to the supported substrate, the fibers have much higher loop strength compared to pure silicone hollow fiber membranes; 2) lower raw material costs, as the expensive PDSP skin contributes less than 15% of the total material; 3) High production rates characterized by a dry-stretching process; 4) The process is simplified since no curing, cleaning or washing steps are required.

[0030] List of Exemplary Embodiments A. An asymmetric hollow fiber membrane, A porous substrate having a plurality of pores, the porous substrate comprising at least one semi-crystalline thermoplastic polyolefin (co)polymer; a skin layer covering the porous substrate; The skin layer comprises at least two repeat units of formula I: [ka] [In the formula, Each R 1 is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is the formula R 3 HN-G-NHR3 Two from -NHR 3 is a divalent residue equivalent to a diamine excluding the R 3 is hydrogen or alkyl, or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; q is an integer equal to or greater than 1. 1. An asymmetric hollow fiber membrane comprising at least one polydiorganosiloxane polyoxamide copolymer comprising: The asymmetric hollow fiber membrane of embodiment A, wherein Bn, p, and q are selected such that the polydiorganosiloxane blocks constitute at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer, and optionally, no more than 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer. CR 1 At least 50 percent of the groups are methyl, and optionally, each R 1 The asymmetric hollow fiber membrane of embodiment A or B, wherein D. The asymmetric hollow fiber membrane of any one of embodiments A to C, wherein each Y is an alkylene having 1 to 10 carbon atoms, a phenylene bonded to an alkylene having 1 to 10 carbon atoms, or a phenylene bonded to a first alkylene having 1 to 10 carbon atoms and a second alkylene having 1 to 10 carbon atoms. The asymmetric hollow fiber membrane of any one of embodiments A to D, wherein EY is alkylene having 1 to 4 carbon atoms. The asymmetric hollow fiber membrane of any one of embodiments A to E, wherein Fn is at least 40. The asymmetric hollow fiber membrane according to any one of embodiments A to F, wherein Gp is ​​1-4. The asymmetric hollow fiber membrane of any one of embodiments A to G, wherein HG is an alkylene, heteroalkylene, arylene, aralkylene, polydiorganosiloxane, or a combination thereof. IR 3 The asymmetric hollow fiber membrane of any one of embodiments A to H, wherein is H or methyl. JY is an alkylene having 3 carbon atoms, R 1 is methyl and R 3 The asymmetric hollow fiber membrane according to any one of embodiments AI, wherein: is H, n is 190, and p is 1. K. The asymmetric hollow fiber membrane of any one of embodiments A-J, wherein the semi-crystalline thermoplastic polyolefin (co)polymer is derived by polymerizing one or more branched or linear alpha olefin monomers selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, or combinations thereof. L. The asymmetric hollow fiber membrane of any one of embodiments A-K, wherein the semi-crystalline thermoplastic polyolefin (co)polymer comprises polyethylene, polypropylene, or a combination thereof. M. The asymmetric hollow fiber membrane of any one of embodiments A-L, wherein the plurality of pores comprises a plurality of micropores. N. The asymmetric hollow fiber membrane of any one of embodiments A through M, wherein the plurality of pores has a diameter from 0.01 micrometers to 1.0 micrometers, and optionally, the plurality of pores has a diameter from 0.02 micrometers to 0.5 micrometers. O. The asymmetric hollow fiber membrane of any one of embodiments A to N, wherein the asymmetric hollow fiber membrane exhibits a porosity of 5% to 80%, and optionally, the asymmetric hollow fiber membrane exhibits a porosity of 10% to 50%. P. The asymmetric hollow fiber membrane of any one of embodiments A-O, wherein the skin layer is less porous than the porous substrate and comprises an outer sheath surface of the asymmetric hollow fiber membrane, and optionally, the porous substrate comprises an inner lumen surface of the asymmetric hollow fiber membrane. Q. The asymmetric hollow fiber membrane of embodiment P, wherein the skin layer is nonporous. R. The asymmetric hollow fiber membrane of any one of embodiments A through Q, wherein the porous substrate further comprises a nucleating agent in an amount effective to achieve nucleation. S. The asymmetric hollow fiber membrane of any one of embodiments A through R, wherein the skin layer has a thickness of less than 20 micrometers, and optionally, the skin layer has a thickness of less than 5 micrometers. T. The asymmetric hollow fiber membrane of any one of embodiments A to S, wherein the porous substrate has a thickness of from 5 micrometers to 200 micrometers, and optionally, the porous substrate has a thickness of from 10 micrometers to 100 micrometers. U. The asymmetric hollow fiber membrane of embodiment T, wherein the porous substrate has a thickness of from 20 micrometers to 50 micrometers, and optionally, the porous substrate has a thickness of from 5 micrometers to 10 micrometers. V. The asymmetric hollow fiber membrane of any one of embodiments A to U, wherein the asymmetric hollow fiber membrane is a heterogeneous asymmetric hollow fiber membrane. W. The asymmetric hollow fiber membrane of any one of embodiments A-V, wherein the skin layer completely covers the porous substrate. X. A separation article comprising a plurality of asymmetric hollow fiber membranes according to any one of embodiments A-W. Y. The separation article of embodiment X, in which a plurality of asymmetric hollow fiber membranes are arranged (e.g., by braiding) in an array, and optionally, the array is pleated, folded, or rolled to form a cylinder or cassette. Z. Separated items are N 2 More than CO 2 In contrast, CH 4 More than CO 2 16. The separation article of claim 15, which is selectively permeable to water vapor over air or to one or more volatile organic compounds over air. AA. The separated article is at least 8, CO 2 / N 2 The separation article of embodiment Z, which exhibits selectivity. BB. The filtration article is N 2 More than O 2 The separation article of embodiment X or Y, which is selectively permeable to. CC. A method of using the separation article of any one of embodiments X, Y, Z, AA, or BB, wherein the separation article is used to separate a gas phase from a liquid phase. DD. The gas phase is N 2 , O 2 , CO 2 , C.H. 4 or a combination thereof. EE. The method of embodiment CC or DD, wherein the liquid phase comprises water; optionally, the liquid phase is an aqueous printing ink, or an aqueous brine. FF. A method for producing an asymmetric hollow fiber membrane, comprising: Providing a substrate resin and a skin layer resin, The substrate resin comprises at least one semi-crystalline thermoplastic polyolefin (co)polymer and the skin layer resin comprises at least two repeat units of formula I: [ka] [In the formula, Each R 1 is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is the formula R 3 HN-G-NHR 3 Two from -NHR 3 is a divalent residue equivalent to a diamine excluding the R 3 is hydrogen or alkyl, or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; q is an integer equal to or greater than 1. providing at least one polydiorganosiloxane polyoxamide copolymer comprising: co-extruding a substrate resin and a skin layer resin to form an asymmetric hollow fiber membrane precursor; and stretching an asymmetric hollow fiber membrane precursor to form an asymmetric hollow fiber membrane having a substantially non-porous skin layer comprised of a skin layer resin overlying a porous substrate comprised of a substrate resin, the porous substrate comprising a plurality of pores. The method of embodiment FF, wherein n, p, and q are such that the polydiorganosiloxane blocks constitute at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer, and optionally constitute up to 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer. HH. The method of embodiment FF or GG, wherein coextruding the substrate resin and the skin layer resin to form an asymmetric hollow fiber membrane precursor comprises coextruding the substrate resin and the skin layer resin through an annular coextrusion die to form an asymmetric hollow fiber membrane precursor. II. The method of any one of embodiments FF, GG, or HH, further comprising annealing the asymmetric hollow fiber membrane precursor. JJ. The method of embodiment II, wherein annealing the asymmetric hollow fiber membrane precursor comprises annealing the asymmetric hollow fiber membrane precursor before stretching the asymmetric hollow fiber membrane precursor. KK. The method of any one of embodiments FF through JJ, wherein the skin layer resin is substantially free of any pore-forming materials in an amount effective to cause pore formation. LL. The method of any one of embodiments FF-KK, wherein coextruding the substrate resin and the skin layer resin to form an asymmetric hollow fiber membrane precursor comprises coextruding the substrate resin and the skin layer resin through an annular coextrusion die to form an asymmetric hollow fiber membrane precursor. MM. The method of any one of embodiments FF-LL, wherein the plurality of pores comprises micropores. NN. The method of embodiment MM, wherein the plurality of pores has a diameter between 0.01 micrometers and 1.0 micrometers, and optionally, the plurality of pores has a diameter between 0.02 micrometers and 0.5 micrometers. OO. The method of any one of embodiments FF through NN, wherein the asymmetric hollow fiber membrane exhibits a porosity between 5% and 80%, and optionally, the asymmetric hollow fiber membrane exhibits a porosity between 10% and 50%. The method of any one of embodiments FF-OO, wherein the PP.skin layer is less porous than the porous substrate and comprises an outer surface of the asymmetric hollow fiber membrane, and optionally, the porous substrate comprises an inner surface of the asymmetric hollow fiber membrane. QQ. The method of any one of embodiments FF-PP, wherein the skin layer is non-porous. RR. The method of any one of embodiments FF through QQ, wherein the porous substrate further comprises a nucleating agent in an effective amount to achieve nucleation, and optionally, the skin layer does not comprise a nucleating agent in an effective amount to achieve nucleation. SS. The method of any one of embodiments FF through RR, wherein the skin layer has a thickness less than 20 micrometers and the skin layer has a thickness less than 5 micrometers. TT. The method of any one of embodiments FF-SS, wherein the porous substrate has a thickness of from 5 micrometers to 200 micrometers. UU. The method of embodiment TT, wherein the porous substrate has a thickness of 10 micrometers to 100 micrometers. VV. The method of embodiment UU, wherein the porous substrate has a thickness of 20 micrometers to 50 micrometers. WW. The method of embodiment TT, wherein the porous substrate has a thickness of from 5 micrometers to 10 micrometers. XX. The method of any one of embodiments FF-WW, wherein the asymmetric hollow fiber membrane is a heterogeneous asymmetric hollow fiber membrane. YY. The method of any one of embodiments FF-XX, wherein the skin layer completely covers the porous substrate. ZZ. The method of any one of embodiments FF through YY, further comprising annealing the asymmetric hollow fiber membrane precursor. The method of embodiment ZZ, wherein annealing the asymmetric hollow fiber precursor comprises annealing the asymmetric hollow fiber membrane precursor before stretching the asymmetric hollow fiber membrane precursor. BBB. The method of any one of embodiments FF-AAA, wherein the skin layer comprises an outer layer, an inner layer, both an outer layer and an inner layer, or an inner layer sandwiched between two other layers of an asymmetric hollow fiber membrane.

[0031] The above is a summary of various aspects and advantages of exemplary embodiments of the present disclosure. The above "Summary" is not intended to describe each illustrated embodiment or every implementation of certain exemplary embodiments of the present disclosure. The following figures and "Description of the Preferred Embodiments" more particularly exemplify certain preferred embodiments that employ the principles disclosed herein. [Brief description of the drawings]

[0032] The present disclosure may be more fully understood from the following detailed description of various embodiments of the disclosure when considered in conjunction with the accompanying drawings, in which: [Figure 1] FIG. 2 is a close-up surface view of an exemplary hollow fiber membrane array useful in producing a porous membrane contactor according to certain embodiments of the present disclosure. [Diagram 2] FIG. 2 is an enlarged perspective view of an end of an exemplary hollow fiber membrane according to certain embodiments of the present disclosure. [Diagram 3] FIG. 2 is an enlarged surface view of a portion of a porous substrate layer forming the interior of a hollow fiber, according to certain embodiments of the present disclosure. [Figure 4A] 1 is a photomicrograph obtained using an optical microscope of an end view of an exemplary hollow fiber membrane according to certain embodiments of the present disclosure. [Figure 4B] 1 is a photomicrograph obtained using an optical microscope of a cross-sectional end view of an exemplary hollow fiber membrane wall, according to certain embodiments of the present disclosure. [Figure 4C] 1 is a photomicrograph obtained using a scanning electron microscope of a porous substrate of an exemplary hollow fiber membrane according to certain embodiments of the present disclosure.

[0033] In the drawings, like reference numbers indicate like elements. The above-identified drawings, which may not be drawn to scale, demonstrate various embodiments of the present disclosure; however, other embodiments are also contemplated, as noted in the Detailed Description, which describes representative illustrative and presently preferred embodiments. It should be understood that numerous other modifications and embodiments may be devised by those skilled in the art that are within the scope and spirit of the disclosure and claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] With regard to the following glossary of defined terms, these definitions shall apply throughout this application, unless a different definition is provided in the claims or elsewhere in this specification.

[0035] Glossary Certain terms are used throughout this specification and claims, most of which are well known, but may require some explanation. Thus, the following should be understood:

[0036] The term "(co)polymer(s)" includes homopolymers and copolymers, as well as homopolymers or copolymers that may be formed in miscible blends, for example, by coextrusion or by reaction, including, for example, transesterification. The term "copolymer" includes random copolymers, block copolymers, and star (e.g., dendritic) copolymers.

[0037] The term "semi-crystalline" for (co)polymers is intended to refer to both partially crystalline and fully crystalline (co)polymers, where the (co)polymer exhibits a crystalline melting temperature as determined using differential scanning calorimetry.

[0038] The term "alkenyl" refers to a monovalent group that is a radical of an alkene, which is a hydrocarbon having at least one carbon-carbon double bond. Alkenyls can be straight-chained, branched, cyclic, or combinations thereof and typically contain 2 to 20 carbon atoms. In some embodiments, alkenyls contain 2 to 18, 2 to 12, 2 to 10, 4 to 10, 4 to 8, 2 to 8, 2 to 6, or 2 to 4 carbon atoms. Exemplary alkenyl groups include ethenyl, n-propenyl, and n-butenyl.

[0039] The term "alkyl" refers to a monovalent group that is a radical of an alkane, which is a saturated hydrocarbon. An alkyl can be straight-chained, branched, cyclic, or a combination thereof, and typically has 1 to 20 carbon atoms. In some embodiments, an alkyl group contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, and ethylhexyl.

[0040] The term "alkylene" refers to a divalent group that is a radical of an alkane. Alkylene may be straight chain, branched chain, cyclic, or a combination thereof. Alkylene often has 1 to 20 carbon atoms. In some embodiments, alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of the alkylene may be on the same carbon atom (i.e., an alkylidene) or on different carbon atoms.

[0041] The term "alkoxy" refers to a monovalent group of formula -OR where R is an alkyl group.

[0042] The term "alkoxycarbonyl" refers to a monovalent group of formula -(CO)OR where R is an alkyl group and (CO) denotes a carbonyl group where the carbon is attached to the oxygen with a double bond.

[0043] The term "aralkyl" refers to a group of the formula -R a -Ar, where R a is an alkylene and Ar is an aryl group, i.e., an aralkyl is an alkyl substituted with an aryl.

[0044] The term "aralkylene" refers to a group of the formula -R a -Ar a -[wherein, R a is alkylene, and Ar a refers to a divalent group in which the alkyl group is an arylene (i.e., an alkylene is bonded to an arylene).

[0045] The term "aryl" refers to a monovalent group that is aromatic and carbocyclic. An aryl can have from 1 to 5 rings that are connected or fused to the aromatic ring. Other ring structures can be aromatic, non-aromatic, or combinations thereof. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, terphenyl, anthryl, naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl, pyrenyl, perylenyl, and fluorenyl.

[0046] The term "arylene" refers to a divalent group that is carbocyclic and aromatic. The group has 1 to 5 rings that are connected, fused, or a combination thereof. The other rings may be aromatic, non-aromatic, or a combination thereof. In some embodiments, the arylene group has up to 5 rings, up to 4 rings, up to 3 rings, up to 2 rings, or one aromatic ring. For example, the arylene group may be phenylene.

[0047] The term "aryloxy" refers to a monovalent group of formula -OAr where Ar is an aryl group.

[0048] The term "carbonyl" refers to a divalent group of formula -(CO)- where a carbon atom is attached to an oxygen atom with a double bond.

[0049] The term "halo" refers to fluoro, chloro, bromo, or iodo.

[0050] The term "haloalkyl" refers to an alkyl in which at least one hydrogen atom is replaced with halo. Some haloalkyl groups are fluoroalkyl, chloroalkyl, or bromoalkyl groups.

[0051] The term "heteroalkylene" refers to a divalent group that includes at least two alkylene groups connected by thio, oxy, or -NR-, where R is alkyl. The heteroalkylene can be linear, branched, cyclic, or a combination thereof and can include up to 60 carbon atoms and up to 15 heteroatoms. In some embodiments, the heteroalkylene includes up to 50 carbon atoms, up to 40 carbon atoms, up to 30 carbon atoms, up to 20 carbon atoms, or up to 10 carbon atoms. Some heteroalkylenes are polyalkylene oxides, where the heteroatoms are oxygen.

[0052] The term "oxalyl" refers to a divalent group of formula -(CO)-(CO)-, where each (CO) denotes a carbonyl group.

[0053] The terms "oxalylamino" and "aminooxalyl" are used interchangeably and refer to a divalent group of formula -(CO)-(CO)-NH-, where each (CO) is a carbonyl.

[0054] The term "aminooxalylamino" refers to a group of the formula -NH-(CO)-(CO)-NR d [wherein each (CO) represents a carbonyl group; Rd refers to a divalent group of hydrogen, alkyl, or both which, together with the attached nitrogen, are part of a heterocyclic group. d is hydrogen or alkyl. In many embodiments, R d is hydrogen.

[0055] The terms "polymer" and "polymeric material" refer to both a material prepared from one type of monomer, such as a homopolymer, or a material prepared from two or more types of monomers, such as a copolymer, terpolymer, etc. Similarly, the term "polymerizing" refers to the process of making a polymeric material, which can be a homopolymer, copolymer, terpolymer, etc. The terms "copolymer" and "copolymeric material" refer to a polymeric material prepared from at least two types of monomers.

[0056] The term "polydiorganosiloxane" refers to divalent blocks or segments of the formula: [ka] In the formula, each R 1 is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy or halo; each Y is independently alkylene, aralkylene, or combinations thereof; and the subscript n is independently an integer from 0 to 1500.

[0057] The term "hollow fiber membrane" means an artificial semipermeable barrier in the form of open tubular filaments of indefinite length.

[0058] The term "asymmetric" with respect to hollow fiber membranes means that the membrane has two major surfaces, an internal lumen surface, and an external sheath surface, that are composite and / or structurally and / or functionally distinct.

[0059] The term "homogeneous" means exhibiting only a single phase of material when observed on a macroscopic scale.

[0060] The term "microporous" with respect to hollow fiber membranes means that the membrane is formed from a solid matrix having defined, generally circular openings or holes (pores) formed therein, where the pores generally have a diameter of at least 10 nm and less than 1 mm.

[0061] The term "non-porous" refers to a dense film in which the permeant is transported by diffusion under the driving forces of concentration, pressure, or potential gradients.

[0062] The term "nucleating agent" means a material that promotes crystallization (nucleation) of semicrystalline polymers during melt processing.

[0063] The term "annealing" for crystalline or semi-crystalline (co)polymers means heating the (co)polymer material at a particular temperature for a time sufficient to change the crystal microstructure and reduce crystalline defects. The annealing temperature is typically below the melting point of the (co)polymer and the duration is long enough to achieve thermal refinement of the crystal structure.

[0064] The term "adjacent" with respect to a particular layer means that the two layers are adjacent (i.e., adjacent) and in direct contact with one another, or are joined or attached to another layer in a position that is adjacent but not in direct contact with one another (i.e., there are one or more additional layers interposed between the layers).

[0065] For the location of various elements in the disclosed coated articles, orientation terms such as "atop," "on," "over," "covering," "uppermost," "overlaying," "underlying," etc. are used to refer to the relative position of the elements with respect to a horizontally disposed, upward-facing substrate. However, unless otherwise indicated, it is not intended that the substrate or article should have any particular spatial orientation during or after manufacture.

[0066] Use of the term "overcoated" to describe the location of a layer relative to a substrate or other element of the articles of the present disclosure refers to the layer being on top of the substrate or other element, but not necessarily in close proximity to the substrate or other element.

[0067] By using the term "separated by" to describe the location of a layer relative to other layers, we are referring to the layer being located between two other layers, but not necessarily adjacent or contiguous to either layer.

[0068] The terms "about" or "approximately" with reference to a numerical value or shape mean ±5 percent of the numerical value or property or characteristic, but expressly include the exact numerical value. For example, a viscosity of "about" 1 Pa·sec refers to a viscosity between 0.95 and 1.05 Pa·sec, but also expressly includes a viscosity of exactly 1 Pa·sec. Similarly, a "substantially square" perimeter is intended to describe a geometric shape having four lateral edges, each lateral edge having a length that is between 95% and 105% of the length of any other lateral edge, but is also intended to include geometric shapes in which each lateral edge has the exact same length.

[0069] The term "substantially" with respect to a property or characteristic means that the property or characteristic is exhibited to a greater extent than the opposite of the property or characteristic is exhibited. For example, a "substantially" transparent substrate refers to a substrate that transmits more radiation (e.g., visible light) than it does not transmit (e.g., absorbs and reflects). In this case, a substrate that transmits more than 50% of the visible light incident on its surface is substantially transparent, while a substrate that transmits 50% or less of the visible light incident on its surface is not substantially transparent.

[0070] The terms "room temperature" and "ambient temperature" are used interchangeably and refer to a temperature in the range of 20°C to 25°C.

[0071] As used herein and in the accompanying embodiments, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a microfiber containing a "compound" includes a mixture of two or more compounds. As used herein and in the accompanying embodiments, the term "or" is generally used in its sense including "and / or" unless the context clearly dictates otherwise.

[0072] As used herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

[0073] Unless otherwise indicated, all numbers expressing quantities or ingredients, measurements of properties, and the like used in the specification and embodiments are to be understood in all instances as being modified by the term "about". Thus, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and the accompanying enumeration of embodiments may vary depending on the desired properties one of ordinary skill in the art would obtain using the teachings of the present disclosure. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques, which is not intended to limit the application of the doctrine of equivalents to the scope of the claimed embodiments.

[0074] Various exemplary embodiments of the present disclosure will be described below with specific reference to the drawings. Various modifications and changes may be made to the exemplary embodiments of the present disclosure without departing from the spirit and scope of the present disclosure. Therefore, it should be understood that the embodiments of the present disclosure are not limited to the exemplary embodiments described below, but are controlled by the limitations set forth in the claims and any equivalents thereof.

[0075] Asymmetric hollow fiber membrane Referring now to FIG. 2, in one embodiment, the present disclosure describes an asymmetric hollow fiber membrane 202 that includes a porous substrate 204 having a plurality of pores and a skin layer 206 covering the porous substrate 204.

[0076] As shown in FIG. 3, a surface 310 of the porous substrate has a plurality of pores 308. In certain currently preferred embodiments, the plurality of pores comprises micropores. In some such embodiments, the micropores have diameters between 0.01 micrometers and 1.0 micrometers. In other embodiments, the micropores have diameters between 0.02 micrometers and 0.5 micrometers. In further exemplary embodiments, the asymmetric hollow fiber membrane exhibits a porosity between 5% and 80%. In other embodiments, the asymmetric hollow fiber membrane exhibits a porosity between 10% and 50%.

[0077] In certain currently preferred embodiments, the skin layer completely covers the porous substrate. In some exemplary embodiments, the skin layer is less porous than the porous substrate and constitutes the outer surface of the asymmetric hollow fiber membrane. In some such embodiments, the porous substrate constitutes the luminal surface and the skin layer constitutes the outer sheath surface of the asymmetric hollow fiber membrane. In certain currently preferred embodiments, the skin layer is non-porous.

[0078] In some exemplary embodiments, the skin layer has a thickness of less than 20 micrometers, or even less than 5 micrometers. In certain such exemplary embodiments, the porous substrate has a thickness of between 5 micrometers and 200 micrometers, between 10 micrometers and 100 micrometers, between 20 micrometers and 50 micrometers, or even between 5 micrometers and 10 micrometers.

[0079] In further exemplary embodiments, the asymmetric hollow fiber membrane is a heterogeneous asymmetric hollow fiber membrane. In certain such embodiments, the skin layer is non-porous or exhibits small diameter pores and the porous substrate exhibits larger diameter pores. In some such embodiments, the membrane morphology is radially isotropic.

[0080] In one particular exemplary embodiment, the asymmetric microporous hollow fiber membrane exhibits the following properties: 2 Gas permeation rate (1GPU=10 -6 seconds / cm 2 -sec-cmHg; CO of 10-12 (e.g., 11.2) 2 / N 2 selectivity, a skin thickness of 2.6 μm; a fiber outer diameter (OD) of approximately 280 μm; a fiber wall thickness of 29 μm; and a total coverage of the skin layer on the porous substrate (ie, 100%).

[0081] Materials for producing asymmetric hollow fiber membranes The present disclosure describes an asymmetric hollow fiber membrane comprising a porous substrate having a multitude of pores and a skin layer covering the porous substrate. The porous substrate comprises at least one semi-crystalline thermoplastic polyolefin (co)polymer resin, and the skin layer comprises at least two repeating units of formula I: [ka] [In the formula, Each R 1 is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is the formula R 3 HN-G-NHR 3 Two from -NHR 3 is a divalent residue equivalent to a diamine excluding the R 3 is hydrogen or alkyl, or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; q is an integer equal to or greater than 1. The composition comprises at least one polydiorganosiloxane polyoxamide copolymer resin comprising:

[0082] Preferably, n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer. In such embodiments, n, p, and q are selected such that the polydiorganosiloxane blocks comprise no more than 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer.

[0083] porous base resin The porous substrate 204 is composed of at least one semi-crystalline thermoplastic polyolefin copolymer, which can be linear or branched.

[0084] The linear or branched semi-crystalline thermoplastic alpha olefin monomer may be selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, isobutylene, vinylcyclohexane, 3-ethyl-1-pentene, 1,3-methyl-1-pentene, cyclobutene, cyclopentane, 2-norbornene, 3-methyl-2-norbornene, 5-methyl-2-norbornene, tetracyclododecene, methyltetracyclododecene, dimethyltetracyclododecene 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, or combinations thereof.

[0085] In certain currently preferred embodiments, the semi-crystalline thermoplastic polyolefin (co)polymer advantageously comprises polyethylene, polypropylene, or a combination thereof.

[0086] Suitable crystalline thermoplastic polypropylene homopolymer porous substrate resins are available from Total Petrochemicals (Houston, TX) under the trade name FINA, such as FINA 3271, FINA 3276, FINA 3281, FINA 3371, FINA 3462, FINA 3480Z, or other trade names such as PPR 3260. Other suitable polypropylene homopolymers are available from Lyondel-Basell Industries (Pasadena, TX) under the trade name PRO-FAX, such as PRO-FAX 1280, PRO-FAX 814, PRO-FAX 1282, PROFAX 1283, or other trade names such as ADFLUEX X500F, ADSYL 3C30F, HP403G, TOPPYL SP 2103. Further suitable polypropylene homopolymers are available from INEOS Olefins & Polymers, USA (Carson, Calif.), such as INEOS H01-00, INEOS H02C-00, INEOS H04G-00, and INEOS H12G-00. Further suitable polypropylene homopolymers are available from Exxon-Mobil Chemical Co. (Spring, Tex.), such as PP1024E4, PP2252E3, PP4292E1, and PP4612E2.

[0087] Suitable crystalline thermoplastic polyethylene (PE) homopolymer porous substrate resins are available from Exxon-Mobil Chemical Co. (Spring, TX), such as HDPE 6908. Suitable polyethylene homopolymers are also available from Total Petrochemicals (Houston, TX), such as HDPE9458, HDPE9460, HL428, HL717, and Total 6480. Other suitable polyethylene homopolymers are available from Braskem Chemical and Plastics Company (LaPorte, TX), such as HF0144, HF0150, HF0147, and FH35.

[0088] In some embodiments, the substrate resin can also include one or more poly(methyl)pentene (PMP) copolymer resins. Suitable grades of PMP copolymer resins having low contents of linear or branched α-olefin comonomers useful as porous substrate resins are available from Mitsui Chemical (Minato-Ku, Tokyo, Japan) under the general trade name TPX, e.g., resin grades DX470, RT18, DX820, and DX845.

[0089] A suitable crystalline thermoplastic polybutene-1 (PB-1) homopolymer porous substrate resin is available under the trade name Akoalit, such as Akoalit PB 4268, from Lyondel-Basell Industries (Pasadena, TX).

[0090] In further exemplary embodiments, the porous substrate can have a thickness ranging from 5 μm to 200 μm, 10 μm to 100 μm, 15 μm to 75 μm, 20 μm to 50 μm, or 25 μm to 35 μm. In some exemplary embodiments, the substrate can have an even smaller thickness (e.g., less than 25 μm, <20 μm, <15 μm, <10 μm, or even about 5 μm) in various film and / or flat sheet exemplary embodiments.

[0091] Skin Layer Resin The skin layer 206 is composed of a polydiorganosiloxane polyoxamide ("PDSP") copolymer that includes at least two repeating units of Formula I below: [ka]

[0092] In this formula, each R 1is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo. Each Y is independently alkylene, aralkylene, or a combination thereof. Subscript n is independently an integer from 0 to 1500, subscript p is an integer from 1 to 10, and subscript q is an integer of 1 or greater.

[0093] The group G has the formula R 3 HN-G-NHR 3 2 pieces of -NHR 3 The R group is a divalent group that is a residue unit equivalent to the diamine without the R group. 3 is hydrogen or alkyl (e.g., alkyl having 1 to 10, 1 to 6, or 1 to 4 carbon atoms), or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group (e.g., R 3 HN-G-NHR 3 is piperazine, etc.). * ) indicates the site at which the repeat unit is attached to another group within the copolymer, such as another repeat unit of formula I.

[0094] R in Formula I 1 Suitable alkyl groups for R typically have 1 to 10, 1 to 6, or 1 to 4 carbon atoms. Exemplary alkyl groups include, but are not limited to, methyl, ethyl, isopropyl, n-propyl, n-butyl, and isobutyl. 1 Suitable haloalkyl groups often have only a portion of the hydrogen atoms of the corresponding alkyl group replaced with halogen.

[0095] Exemplary haloalkyl groups include chloroalkyl and fluoroalkyl groups having 1 to 3 halo atoms and 3 to 10 carbon atoms. 1Alkenyl groups suitable for R often have 2 to 10 carbon atoms. Exemplary alkenyl groups such as ethenyl, n-propenyl, and n-butenyl often have 2 to 8, 2 to 6, or 2 to 4 carbon atoms. 1 Suitable aryl groups for often have 6 to 12 carbon atoms. Phenyl is an exemplary aryl group. The aryl group can be unsubstituted or substituted with alkyl (e.g., alkyl having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms), alkoxy (e.g., alkoxy having 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms), or halo (e.g., chloro, bromo, or fluoro). 1 Suitable aralkyl groups for typically have an alkylene group having 1 to 10 carbon atoms and an aryl group having 6 to 12 carbon atoms.

[0096] In some exemplary aralkyl groups, the aryl group is phenyl and the alkylene group has 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms (i.e., the aralkyl structure is alkylene-phenyl, where the alkylene is attached to a phenyl group).

[0097] In some repeat units of formula I, R 1 At least 50 percent of the groups are methyl. For example, R 1 At least 60 percent, at least 70 percent, at least 80 percent, at least 90 percent, at least 95 percent, at least 98 percent, or at least 99 percent of the groups may be methyl. 1 The groups may be selected from alkyl having at least 2 carbon atoms, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy or halo.

[0098] Each Y in formula I is independently an alkylene, an aralkylene, or a combination thereof. Suitable alkylene groups typically have up to 10 carbon atoms, up to 8 carbon atoms, up to 6 carbon atoms, or up to 4 carbon atoms. Exemplary alkylene groups include methylene, ethylene, propylene, and butylene. Suitable aralkylene groups typically have an arylene group having 6 to 12 carbon atoms bonded to an alkylene group having 1 to 10 carbon atoms. In some exemplary aralkylene groups, the arylene moiety is phenylene. That is, the divalent aralkylene group is a phenylene-alkylene, where the phenylene is bonded to an alkylene having 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. As used herein, with respect to the Y group, "combinations thereof" refers to a combination of two or more groups selected from alkylene groups and aralkylene groups. For example, the combination can be a single aralkylene bonded to a single alkylene (e.g., alkylene-arylene-alkylene). In one exemplary alkylene-arylene-alkylene combination, the arylene is phenylene and each alkylene has 1 to 10, 1 to 6, or 1 to 4 carbon atoms.

[0099] Each subscript n in formula I is independently an integer from 0 to 1500. For example, subscript n can be an integer from at most 1000, at most 500, at most 400, at most 300, at most 200, at most 100, at most 80, at most 60, at most 40, at most 20, or at most 10. The value of n is often at least 1, at least 2, at least 3, at least 5, at least 10, at least 20, or at least 40. For example, subscript n can be in the range of 40 to 1500, 0 to 1000, 40 to 1000, 0 to 500, 1 to 500, 40 to 500, 1 to 400, 1 to 300, 1 to 200, 1 to 100, 1 to 80, 1 to 40, or 1 to 20.

[0100] The subscript p is an integer from 1 to 10. For example, the value of p is often an integer at most 9, at most 8, at most 7, at most 6, at most 5, at most 4, at most 3, or at most 2. The value of p can be in the range of 1 to 8, 1 to 6, or 1 to 4.

[0101] Preferably, n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer. In such embodiments, n, p, and q are selected such that the polydiorganosiloxane blocks comprise no more than 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer.

[0102] The group G in formula I is of the formula R 3 HN-G-NHR 3 to two amino groups (i.e., -NHR 3 The diamine may have primary or secondary amino groups. 3 is hydrogen or alkyl (e.g., alkyl having 1 to 10, 1 to 6, or 1 to 4 carbon atoms), or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group (e.g., R 3 HN-G-NHR 3 is piperazine). In most embodiments, R 3 is hydrogen or alkyl. In many embodiments, both of the amino groups of the diamine are primary amino groups (i.e., R 3 The diamine has the formula H 2 NG-NH 2 It is a diamine.

[0103] In some embodiments, G is an alkylene, heteroalkylene, polydiorganosiloxane, arylene, aralkylene, or a combination thereof. Suitable alkylenes often have 2 to 10, 2 to 6, or 2 to 4 carbon atoms. Exemplary alkylene groups include ethylene, propylene, butylene, and the like. Suitable heteroalkylenes often are polyoxyalkylenes, such as polyoxyethylene having at least two ethylene units, polyoxypropylene having at least two propylene units, or copolymers thereof.

[0104] Suitable polydiorganosiloxanes include the polydiorganosiloxane diamines described below minus two amino groups. Exemplary polydiorganosiloxanes include, but are not limited to, polydimethylsiloxanes having alkylene Y groups. Suitable aralkylene groups typically contain an arylene group having 6 to 12 carbon atoms bonded to an alkylene group having 1 to 10 carbon atoms. Some exemplary aralkylene groups are phenylene-alkylenes, where the phenylene is bonded to an alkylene having 1 to 10 carbon atoms, 1 to 8 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. As used herein, "combinations thereof" with respect to the group G refers to combinations of two or more groups selected from alkylene, heteroalkylene, polydiorganosiloxane, arylene, and aralkylene. The combination may be, for example, an aralkylene bonded to an alkylene (e.g., alkylene-arylene-alkylene). In one exemplary alkylene-arylene-alkylene combination, the arylene is phenylene and each alkylene has 1 to 10, 1 to 6, or 1 to 4 carbon atoms.

[0105] The polydiorganosiloxane polyoxamide has the formula -R a -(CO)-NH-[wherein, R ais alkylene. All of the carbonylamino groups along the backbone of the copolymer material are part of an oxalylamino group (i.e., a -(CO)-(CO)-NH- group). That is, every carbonyl group along the backbone of the copolymer material is bonded to another carbonyl group and is part of an oxalyl group. More specifically, polydiorganosiloxane polyoxamides have multiple aminooxalylamino groups.

[0106] Polydiorganosiloxane polyoxamides are linear block copolymers and can be elastomeric materials. Unlike many known polydiorganosiloxane polyamides, which are generally formulated as brittle solids or hard plastics, polydiorganosiloxane polyoxamides can be formulated to contain more than 50 weight percent polydiorganosiloxane segments based on the weight of the copolymer. The weight percent of diorganosiloxane in polydiorganosiloxane polyoxamides can be increased by using higher molecular weight polydiorganosiloxane segments, providing more than 60 weight percent, more than 70 weight percent, more than 80 weight percent, more than 90 weight percent, more than 95 weight percent, or more than 98 weight percent polydiorganosiloxane segments in the polydiorganosiloxane polyoxamide. By using higher amounts of polydiorganosiloxane, elastomeric materials can be prepared that have a lower modulus while still maintaining adequate strength.

[0107] Some of the polydiorganosiloxane polyoxamides can be heated to temperatures up to 200° C., up to 225° C., up to 250° C., up to 275° C., or up to 300° C. without significant decomposition of the material. For example, when heated in a thermogravimetric analyzer in the presence of air, the copolymers often have a weight loss of less than 10 percent when scanned at a rate of 50° C. per minute over the range of 20° C. to about 350° C. Furthermore, the copolymers can often be heated in air at temperatures such as 250° C. for an hour without appreciable degradation, as measured by no detectable loss of mechanical strength upon cooling.

[0108] Optionally, non-reactive additives such as, for example, fillers, pigments, stabilizers, antioxidants, flame retardants, compatibilizers, and the like, can be added to the copolymer material.

[0109] The polydiorganosilane polyoxamides are soluble in many common organic solvents, such as, for example, toluene, tetrahydrofuran, dichloromethane, aliphatic hydrocarbons (eg, alkanes such as hexane), or mixtures thereof.

[0110] The polydiorganosiloxane polyoxamides can be cast from a solvent as a film, molded or embossed into various shapes, or extruded into a film. The high temperature stability of the copolymer materials makes them well suited for extrusion methods of film formation.

[0111] In some exemplary embodiments, each Y is an alkylene having 1 to 10 carbon atoms, a phenylene bonded to an alkylene having 1 to 10 carbon atoms, or a phenylene bonded to a first alkylene having 1 to 10 carbon atoms and a second alkylene having 1 to 10 carbon atoms.

[0112] In further exemplary embodiments, G is an alkylene, heteroalkylene, arylene, aralkylene, polydiorganosiloxane, or combinations thereof. 3is advantageously chosen to be H or methyl.

[0113] In some currently preferred embodiments, R 1 At least 50 percent, at least 60 percent, at least 70 percent, at least 80 percent, at least 90 percent, or even 100 percent of the groups are methyl.

[0114] In additional currently preferred embodiments, n is at least 40, at least 50, at least 75, at least 100, at least 250, at least 500, at least 750, at least 1,000, or even up to 1500. In some such exemplary embodiments, n can be 1400 or less, 1300 or less, 1200 or less, 1100 or less, 1000 or less, 750 or less, 500 or less, 250 or less, or even 100 or less.

[0115] Suitable polydiorganosiloxane polyoxamide copolymers (PDSPs) and methods for making such PDSP copolymers are disclosed in US Pat. No. 7,501,184, the entire disclosure of which is incorporated herein by reference in its entirety.

[0116] In various implementations involving multi-layer microporous membranes, a skin layer can be disposed as any layer of a multi-layer asymmetric hollow fiber; for example, a PDSP skin can constitute one or more outer and / or inner layers of a multi-layer asymmetric hollow fiber that includes multiple layers, e.g., three or more layers.

[0117] In various exemplary embodiments, the PDSP skin can be the outer exposed surface of a hollow fiber, or the luminal surface of a hollow fiber, or an internal layer sandwiched between two other layers in a multi-layer hollow fiber membrane.

[0118] Furthermore, in the case of asymmetric hollow fibers, the PDSP skin may be advantageously disposed on the shell side or cavity side of such hollow fibers.

[0119] Additionally, the temperature stability of the membranes described herein may be improved compared to other known membranes because the softening point of the PDSP copolymer may add temperature stability to the asymmetric hollow fibers.

[0120] The PDSP copolymer can be subjected to further post-treatments to increase the chemical resistance and mechanical strength of the film. For example, the PDSP copolymer can be optionally treated with actinic radiation, for example with ultraviolet, visible, or infrared radiation, or ionizing radiation, for example with electron beam radiation or gamma radiation, to react and / or chemically crosslink the copolymer with one or more radiation-curable materials.

[0121] Additionally, asymmetric hollow fibers formed from PDSP skin layers and PE or PP microporous substrate layers can offer the benefit of having higher gas permeability than other membranes due to the high porosity of the microporous substrate. In various implementations described herein, microporous substrates having porosity greater than 20%, or greater than 25%, or greater than 35%, or greater than 40% can be used.

[0122] The PDSP copolymer skin is advantageously selected to provide a non-porous skin, such as a solid skin that does not contain pores (or a skin that is impermeable to liquids but is permeable to gases) disposed on a microporous substrate. Images of example non-porous skins are provided in Figures 4A and 4B. Figure 4A provides a first image of an exemplary non-porous PDSP copolymer skin on a porous substrate. Figure 4B provides a second image of an exemplary non-porous PDSP copolymer skin on a porous substrate. As can be seen, the PDSP skin is substantially free of defects.

[0123] The properties of the PDSP skin layer can be attributed in part to the dry stretch process (or CELGARD® process) by which the instant microporous membrane is produced. An exemplary dry stretch process includes providing a polydiorganosiloxane polyoxamide ("PDSP") copolymer and a substrate resin, coextruding the PDSP copolymer and the substrate resin to form an asymmetric hollow fiber membrane precursor, and stretching the asymmetric hollow fiber membrane precursor to form an asymmetric hollow fiber having a PDSP skin on a porous substrate.

[0124] No solvents or phase inversions are used in the dry-draw process to form the asymmetric hollow fibers. Similarly, in the various implementations of the CELGARD® process described herein, no porosity is introduced into the PDSP skin layers.

[0125] The thickness of the PDSP skin can depend on the particular application in which the microporous asymmetric hollow fiber is used. In exemplary implementations, the PDSP skin can be 20 micrometers (μm) or less in thickness, 15 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, 7 μm or less, 6 μm or less, 5 μm or less, 3 μm or less, or even approximately 2 μm in thickness. In various implementations, reducing the thickness of the PDSP skin results in a more efficient asymmetric microporous asymmetric hollow fiber membrane.

[0126] In some embodiments, the PDSP skin can have a thickness in the range of 1 μm to 50 μm, 2 μm to 40 μm, 3 μm to 30 μm, 4 μm to 20 μm, 5 μm to 15 μm, or 5 μm to 10 μm. In some implementations, the substrate can have even smaller thicknesses (e.g., less than 5 μm, 4 μm, 3 μm, 2 μm, or even 1 μm) in various film and / or flat sheet implementations.

[0127] In certain exemplary embodiments, some of the skin layer PDSP material may penetrate into the substrate layer and become physically entangled with the at least one semi-crystalline thermoplastic polyolefin copolymer.

[0128] Any nucleating agent In certain exemplary embodiments, the porous substrate resin advantageously further comprises a nucleating agent in an amount effective to achieve nucleation. Suitable nucleating agents are known to those skilled in the art and include alpha-nucleating agents and beta-nucleating agents.

[0129] Alpha-nucleating agents can be either melt nucleating agents or insoluble nucleating agents. Melt nucleating agents are nucleating agents that melt during blending of the melt blend, but recrystallize before the polymer separates from the mixture and crystallizes. Exemplary melt nucleating agents include, but are not limited to, arylalkanoic acid compounds, benzoic acid compounds, dicarboxylic acid compounds, and sorbitol acetal compounds.

[0130] Exemplary melt nucleating agents include, but are not limited to, dibenzylidine sorbitol, adipic acid, benzoic acid, and sorbitol acetal compounds. Exemplary commercially available melt nucleating agents include, but are not limited to, MILLAD® 3988 and MILLAD® NX8000 available from Milliken Chemical (Spartanburg, SC), or NA-806A available from Amfine Chemical Corporation (Hasbrouck Heights, NJ).

[0131] An insoluble alpha nucleating agent is one that does not melt during blending of the melt blend. In general, a material can be useful as an insoluble nucleating agent if it can be uniformly dispersed in the melt blend as discrete particles that can act as heterogeneous nucleation sites for the polymer components.

[0132] Exemplary insoluble nucleating agents include, but are not limited to, inorganic particulate materials and pigments. Exemplary inorganic particulate materials include bicyclo[2.2.1]heptane-2,3-dicarboxylic acid, disodium salt (available under the trade name HYPERFORM® HPN-20E from Milliken & Company, Spartanburg, SC), TiO 2Examples of suitable inorganic fillers include, but are not limited to, talc, fine metal particles, or fine particles of polymeric materials such as polytetrafluoroethylene.

[0133] Exemplary pigments include, but are not limited to, copper phthalocyanine blue or green pigments, as well as D&C Red 6 (disodium salt). The particular nucleating agent used can be selected based on one or more criteria, such as the polyolefin (co)polymer used in the porous substrate, the desired pore size in a particular zone of the porous membrane, etc.

[0134] Alpha nucleating agents only aid in the formation of alpha crystals (monoclinic crystal structure). There are also useful beta nucleating agents that are effective in producing beta crystals (hexagonal unit cell crystal structure). Exemplary beta nucleating agents include, but are not limited to, quinacridone dyes, aluminum salts of 6-quinazolinesulfonic acid, disodium salts o-phthalic acid, isophthalic acid and terephthalic acid, and N,N'-dicyclohexyl-2,6-naphthalenedicarboximide compounds. Exemplary commercially available beta nucleating agents include, but are not limited to, MPM 2000 available from Mayzo, Inc. (Suwanee, GA).

[0135] Suitable nucleating agents for polyethylene (PE) porous substrate resins include, but are not limited to, inorganic nano-sized (i.e., having a particle size or diameter of less than 1 micrometer) fillers such as calcium carbonate, titanium dioxide, barium sulfate, silicon dioxide, graphite, carbon nanotubes, montmorillonite clay, talc, halloysite, or organic fillers such as ultra-high molecular weight PE, polymer fibers, anthracene, potassium hydrogen phthalate, benzoic acid type compounds, sodium benzoate type compounds, and zinc monoglycerolate. Other suitable melt nucleating agents are listed in Polymer Engineering & Science, Vol. 5, (2016), page 541.

[0136] In some exemplary embodiments, a molten nucleating agent can be used alone. In other exemplary embodiments, an insoluble nucleating agent can be used alone. In some particular embodiments, a molten nucleating agent can be advantageously used in combination with an insoluble nucleating agent.

[0137] The nucleating agent is used in the melt blend in an amount sufficient to initiate crystallization of the polymer at the nucleation sites during fiber formation. The amount of nucleating agent required will depend at least in part on one or more of the particular (co)polymer used, the desired porosity and pore size, the particular nucleating agent used, and the like. In some exemplary embodiments, the melt blend can advantageously include 5% or less by weight of nucleating agent based on the total weight of the melt blend. In other exemplary embodiments, the melt blend can include between about 100 parts per million (ppm) and less than 5% by weight of nucleating agent based on the total weight of the melt blend. In further exemplary embodiments, the melt blend can include between 2% or less by weight of nucleating agent based on the total weight of the melt blend. In other exemplary embodiments, the melt blend can include between about 200 ppm and less than 2% by weight of nucleating agent based on the total weight of the melt blend.

[0138] Method for producing asymmetric hollow fiber member In a further embodiment, the present disclosure describes a method of making an asymmetric hollow fiber membrane comprising providing at least one substrate resin and at least one skin layer resin, co-extruding the substrate resin and the skin layer resin to form an asymmetric hollow fiber membrane precursor, and stretching the asymmetric hollow fiber membrane precursor to form an asymmetric hollow fiber membrane having a skin layer made from the skin layer resin covering a porous substrate made from the substrate resin and having a multitude of pores.

[0139] The substrate resin comprises at least one semi-crystalline thermoplastic polyolefin (co)polymer and the skin layer comprises at least two repeating units of formula I: [ka] [In the formula, Each R 1is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is the formula R 3 HN-G-NHR 3 Two from -NHR 3 is a divalent residue equivalent to a diamine excluding the R 3 is hydrogen or alkyl, or R 3 together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; q is an integer equal to or greater than 1. The polydiorganosiloxane polyoxamide copolymer resin comprises

[0140] Preferably, n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent (wt%), at least 60 wt%, at least 80 wt%, at least 85 wt%, at least 90 wt%, or even at least 95 wt% of the polydiorganosiloxane polyoxamide copolymer. In such embodiments, n, p, and q are selected such that the polydiorganosiloxane blocks comprise no more than 99.9 wt%, 99.8 wt%, 99.7 wt%, or even 99.5 wt% of the polydiorganosiloxane polyoxamide copolymer.

[0141] The semi-crystalline thermoplastic polyolefin (co)polymers are derived by polymerizing one or more branched or linear alpha olefin monomers selected from the group consisting of ethylene, propylene, 1-butene, 1-pentene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, or combinations thereof.

[0142] The semi-crystalline thermoplastic polyolefin (co)polymer preferably comprises polyethylene, polypropylene, or a combination thereof, and more preferably the polyolefin (co)polymer consists or consists essentially of polypropylene.

[0143] In some exemplary embodiments, the skin layer resin is substantially free of any pore-forming material in an amount effective to cause pore formation, hi some such embodiments, co-extruding the substrate resin and the skin layer resin to form the asymmetric hollow fiber membrane precursor comprises co-extruding the substrate resin and the skin layer resin through an annular co-extrusion die to form the asymmetric hollow fiber membrane precursor.

[0144] In certain exemplary embodiments, the method further comprises annealing the asymmetric hollow fiber membrane precursor prior to stretching the asymmetric hollow fiber membrane precursor. Annealing is preferably performed by exposing the asymmetric hollow fiber membrane precursor to a heat source, such as an oven or infrared heat lamp, for a specified period of time. Annealing can be performed either under relaxed conditions with minimal tension imposed on the asymmetric hollow fiber membrane precursor, or under tensioned conditions. Annealing can be performed in a continuous, semi-continuous, or batch process.

[0145] The microporous membranes described herein can be produced from a variety of production methods, depending on the desired asymmetric hollow fiber structure and the desired asymmetric hollow fiber composition. The microporous membranes can be produced according to a variety of production techniques, such as the wet process, the dry stretch process (also known as the CELGARD process), and the particle stretch process.

[0146] Generally, in wet processes (also known as phase inversion, extraction, or TIPS processes), a polymeric feedstock is mixed with oil, processing oil, solvent, and / or other materials, the mixture is extruded, and pores are then formed when such oil, processing oil, solvent, and / or other materials are removed. These films may be stretched before or after removal of the oil, solvent, and / or other materials.

[0147] Generally, the microporous membranes are preferably formed via the CELGARD® process, also referred to as the "extrusion, annealing, stretch" or "dry stretch" process, whereby a semi-crystalline polymer is extruded to provide an asymmetric hollow fiber membrane precursor and porosity is induced in the microporous substrate by stretching the extruded precursor.

[0148] Generally, in the particle stretching process, polymer raw materials are mixed with particles, and the mixture is extruded, and pores are formed during stretching when the interface between the polymer and the particulates is fractured due to the stretching force. Dry processes are different from wet and particle stretching processes by producing porous asymmetric hollow fibers, typically without adding processing oils, oils, solvents, plasticizers, etc., or particulate materials. Generally, dry stretching processes refer to processes in which pore formation results from stretching a non-porous precursor.

[0149] Although the membranes produced by the dry stretching process have met with great commercial success, there is a need to improve their physical attributes so that they can be used in a wider range of applications. Thus, asymmetric hollow fibers are described that include a PDSP copolymer skin disposed on a porous polyolefin substrate to provide functionality that may be suitable for, for example, battery separators (useful in consumer electronics applications and electric or hybrid electric vehicle applications), blood oxygenation applications, blood filtration applications, various applications where liquids need to be degassed, and inkjet printing applications for degassing or degassing inks, and that may be well suited for use in hollow fiber asymmetric hollow fiber contactors or modules.

[0150] The method may also advantageously include a step of annealing the asymmetric hollow fiber membrane precursor prior to the stretching step. In an exemplary implementation, the annealing step may include heating the asymmetric hollow fiber membrane precursor at a temperature of about 150° C. for about 10 minutes.

[0151] The step of co-extruding a PDSP copolymer skin layer resin and a polyolefin substrate resin to form an asymmetric hollow fiber membrane precursor may include extruding the skin resin and substrate resin through a co-extrusion die to form the PDSP skin layer on a porous polyolefin substrate layer. The co-extrusion die may be configured based on the desired thickness of the PDSP skin layer and the polyolefin substrate layer. Thus, in an exemplary embodiment, the substrate layer is thicker than the PDSP skin layer.

[0152] Another exemplary method for making an asymmetric hollow fiber having a PDSP skin and a porous polyolefin substrate as described herein can include providing a skin layer resin and a substrate resin, coextruding the skin layer resin and the substrate resin to form an asymmetric hollow fiber membrane precursor, and stretching the asymmetric hollow fiber membrane precursor to form an asymmetric microporous asymmetric hollow fiber having a skin layer on the porous substrate. The method can also include annealing the asymmetric hollow fiber membrane precursor prior to the stretching step.

[0153] Another exemplary method for producing an asymmetric hollow fiber having a PDSP copolymer skin and a porous polyolefin substrate as described above can include the steps of providing a PDSP copolymer resin and a substrate resin, co-extruding the PDSP copolymer resin and the substrate polyolefin resin to form an asymmetric hollow fiber membrane precursor, and stretching the asymmetric hollow fiber membrane precursor to form an asymmetric hollow fiber comprising a PDSP skin layer on a porous polyolefin substrate. The substrate resin can include one or more polyolefins, such as polyethylene (PE), polypropylene (PP), or a combination thereof. The method can also include annealing the asymmetric hollow fiber membrane precursor of the hollow fiber prior to the stretching step.

[0154] Preferably, the annealing temperature is selected below the melting point of the substrate polymer, for example, a PP substrate is preferably annealed at a temperature of 100° C. to 150° C. Annealing times can be from a few seconds to a few hours, preferably 1 to 30 minutes, more preferably 5 to 20 minutes. Higher annealing temperatures generally allow the use of shorter annealing times.

[0155] The drawing can be advantageously carried out using a single or multiple stage cold drawing, optionally followed by a single or multiple stage hot drawing. Preferably, the temperature of the cold drawing is below the glass transition temperature (T g The hot stretching temperature is preferably selected to be 5°C to 70°C, more preferably 10°C to 50°C higher than the melting temperature of the base polymer. For example, the PP substrate is preferably stretched at 20°C to 30°C (PP glass transition temperature is -10°C). The hot stretching temperature is preferably selected to be 10°C to 120°C, more preferably 20°C to 60°C lower than the melting temperature of the base polymer. For example, the PP substrate is preferably stretched at 100°C to 140°C.

[0156] The hollow fibers are advantageously stretched by uniaxial elongation of at least 5% and up to 500%, more preferably at least 10% and up to 300%, to form an open porous structure.

[0157] The drawn hollow fibers can be advantageously exposed to a step of heat-setting to reduce stresses within the fiber. The heat-setting temperature is typically selected to be at least 5° C., at least 10° C., or even at least 15° C. higher than the hot drawing temperature. The heat-setting duration is typically selected to be at least 30 seconds, at least 1 minute.

[0158] Alternatively, the hollow fibers after drawing may be advantageously exposed to a relaxation step by allowing the fiber length to shrink to a certain extent, advantageously at least 2%, or even at least 5%. Heat setting and relaxation can be used alone or in combination.

[0159] Hollow Fiber Membrane Contactor Referring again to the figures, Figure 1 shows an exemplary hollow fiber membrane contactor component 100 in which a plurality of asymmetric hollow fiber membranes 102 are arranged substantially parallel in an array pattern, in this case fastened together by braiding or tying the individual hollow fiber membranes 102 using strings, threads, yarns, or the like 104. Thus, in a further exemplary embodiment, the present disclosure describes a separation article including a multiplicity of asymmetric hollow fiber membranes according to any of the foregoing embodiments.

[0160] In some exemplary embodiments, multiple asymmetric hollow fiber membranes are arranged in an array, and in certain such embodiments, the array is pleated, folded, or rolled into a cylinder or cassette.

[0161] In some exemplary embodiments, the separation article is 2 or CH 4 More than CO 2 Preferably, the separation article is selectively permeable to at least 8, 9, 10, 11, or even 12 CO 2 / N 2 In another exemplary embodiment, the filtration article exhibits selectivity. 2 More than O 2It is selectively permeable to

[0162] In a further aspect, the disclosure describes a method of using any of the aforementioned separation articles, wherein the separation article is used to separate a gas phase from a liquid phase. In some embodiments, the gas phase is N 2 , O 2 , CO 2 , C.H. 4 or a combination thereof.

[0163] In certain embodiments, the gas phase comprises water vapor. In some such embodiments, the separation article is selectively permeable to water vapor relative to air. In certain such embodiments, the separation article may be useful for humidifying or dehumidifying the gas phase.

[0164] In certain embodiments, the gas phase includes one or more volatile organic compounds. In such embodiments, the separation article can be useful in removing the volatile organic compounds from the gas phase.

[0165] In some embodiments, the liquid phase comprises liquid water. Optionally, the liquid phase is an aqueous printing ink or an aqueous brine. In some embodiments, the liquid phase comprises one or more organic compounds. For example, the liquid phase may contain one or more organic alcohols, ketones, ethers, esters, or hydrocarbon solvents. In some such embodiments, the liquid phase may comprise one or more surfactants. For example, the liquid phase may comprise one or more nonionic, anionic, cationic, or amphoteric surfactants.

[0166] A hollow fiber membrane contactor typically includes a cylindrical bundle or mat of asymmetric hollow fibers and a rigid cylindrical shell or housing that encloses the fiber bundle. The shell can include multiple ports, for example, four fluid ports, an inlet for introducing a first fluid, an outlet for discharging the first fluid, an inlet for introducing a second fluid, and an outlet for discharging the second fluid. The hollow fibers can be embedded at both ends within the housing to form a polymeric tubesheet with fiber holes that open at each end into first and second end cap portions of the shell.

[0167] The number of windings or layers of the hollow fiber array or fabric determines the depth of the panel. The end result is a hollow fiber array with height X, width Y, and depth Z. The hollow fiber array may be embedded directly into a square or rectangular frame in a shape similar to an HVAC air filter. In at least one embodiment, the gas to be treated passes through the contactor array on the shell side (outside the hollow fibers) in a cross-flow pattern, and the liquid (hot, cold, humidified, or absorbent liquid) passes through the lumen side (inside the hollow fibers) of the contactor array.

[0168] In at least certain embodiments, the present disclosure is directed to a method of producing or manufacturing an asymmetric hollow fiber membrane contactor. In at least one embodiment, a hollow fiber panel contactor is produced by a method that includes winding a hollow fiber membrane array around a paddle to form a square or rectangular fiber bundle. The number of windings or layers determines the depth or thickness of the panel. The end result is a fiber array having a height X, width Y, and depth Z. The wound array is then removed from the paddle and directly embedded into a square or rectangular frame similar in size and shape to a heating, ventilation, and air conditioning (HVAC) air filter.

[0169] If necessary, the ends of the hollow fibers are opened and a lumen-side fluid headspace is created or added at each end. Such panel contactors are adapted so that air passes through the array on the shell side (outside the hollow fibers) in a cross-flow pattern and liquid (hot, cold, humidified, and / or absorbent liquid) passes through the lumen side (inside the hollow fibers) of the contactor array or a vacuum is applied to the lumen side.

[0170] In at least one other embodiment, the panel contactor is produced by a method that includes pleating or folding (e.g., z-folding, accordion folding, or pleating, and then optionally rolling) a hollow fiber membrane array to form a fiber bundle in a square or rectangular format. The number of folds or layers can determine the depth of the panel. The end result is a fiber array having height X, width Y, and depth Z. The folded or pleated array is then embedded into a square or rectangular frame in a shape similar to an HVAC air filter.

[0171] If necessary, the ends of the hollow fibers are opened and a lumen-side fluid headspace is created or added at each end. Such panel contactors are adapted so that air passes through the array on the shell side (outside the hollow fibers) in a cross-flow pattern and liquid (hot, cold, humidified, and / or absorbent liquid) passes through the lumen side (inside the hollow fibers) of the contactor array or a vacuum is applied to the lumen side.

[0172] In at least certain embodiments, the present disclosure is directed to uses or methods of using flat panel hollow fiber array contactors. In at least one embodiment, the panel contactors are used in a method that includes passing air to be treated through the contactor array on the shell side (outside the hollow fibers) in a cross-flow pattern while simultaneously passing a liquid (hot, cold, humidified, and / or absorbent liquid) through the cavity side (inside the hollow fibers) of the contactor array. Thus, the contactor is a cavity side liquid contactor.

[0173] In at least one other embodiment, the panel contactor is used by or in a method that includes passing a liquid to be treated through the contactor array on the shell side (outside the hollow fibers) in a cross-flow pattern at the same time that a second liquid or gas passes through the lumen side (inside the hollow fibers) of the contactor array, and thus the contactor is a shell-side liquid contactor.

[0174] Other uses of the disclosed panel contactors include: 2 Scrub, greenhouse gas scrub, SO x Scrubs, no x Examples include scrubbing, HCl scrubbing, ammonia scrubbing, gas humidification, gas dehumidification, absorption of moisture and latent heat for energy recovery in HVAC systems, air emission control of off-flavors (e.g., on cattle or swine farms), and / or gas temperature control by changing humidity levels (such as in evaporative cooling or swamp coolers).

[0175] Thus, in accordance with at least selected embodiments of the present disclosure, the new or improved hollow fiber membrane contactors of the present invention address the shortcomings of conventional contactors, are effective for several applications, are specifically adapted for particular conditions, are capable of rapid customer familiarity and acceptance, are free of metals or other corrosive materials, are PVC-free, are modular, are replaceable, have standard air filter sizes, accommodate high air flow velocities, have low shell-side pressure drop, are commercially manufacturable, and the like.

[0176] In at least one embodiment, a self-contained hollow fiber membrane contactor, filter, or cartridge may include at least a first hollow fiber array including a plurality of at least a first hollow fiber membranes, each having a first end and a second end that are both open, at least one rectangular frame, shell, casing, or housing, and potting at each end. The first and second membrane ends are open, for example, to allow liquid to pass therethrough. It may be preferred that the hollow fibers are polyolefin, the frame is ABS, and the potting is made of epoxy, with the ends of the potting being cut to form the first and second hollow fiber ends that are open after potting.

[0177] According to at least selected embodiments, a flat panel contactor combination or system includes two or more hollow fiber membrane panel contactors connected in series or parallel. According to at least embodiments, a flat panel contactor combination or system includes two or more hollow fiber membrane panel contactors connected in series with the frames of adjacent contactors abutting and aligned with each other (optional gaskets can be placed between the abutting frames and / or between the end frames and the piping to provide an airtight seal therebetween).

[0178] According to at least selected possibly preferred embodiments, the present panel membrane contactor (or membrane cartridge) preferably uses thousands of asymmetric microporous hollow fibers woven into an array that is wound, pleated, folded, and / or a combination thereof, for example, into a paddle or similar configuration. During preferred operation, air to be treated flows into the shell side (outside) of the hollow fibers, while liquid desiccant flows through or into the lumen side or lumen side (inside) of the hollow fibers. Due to its hydrophobic nature, the membrane acts as an inert support, allowing direct contact between the gas and liquid phases without dispersion.

[0179] In accordance with certain embodiments of the present invention, novel contactors, contactor systems, and methods for treating one fluid with another fluid are provided.

[0180] Typical applications include oxygen removal from boiler water, beverage carbonation, nitrification, and ink degassing. The systems used for gas generation / degassing are also known as membrane contactors. A gas-liquid interface is formed on the surface of a microporous membrane due to the hydrophobicity and small pore size of the fibers. The efficiency of hollow fiber membrane contactors is determined primarily by the membrane gas transfer rate, which depends on the fiber permeability and available fiber surface area within the module.

[0181] A typical hollow fiber membrane contactor consists of hundreds to thousands of asymmetric hollow fibers with a porosity of at least 40%. The smaller fiber diameter allows for higher fiber packing density, which can provide a higher total membrane surface area compared to flat sheet membranes.

[0182] How to use hollow fiber membrane contactor The present disclosure also describes methods of using any of the aforementioned separation articles, where the separation articles are used to separate a gas phase from a liquid phase. Thus, in a further exemplary embodiment, the present disclosure is directed to methods of using asymmetric hollow fiber membrane contactors. Such asymmetric hollow fiber membrane contactors and / or uses can address one or more of the above-mentioned needs or shortcomings of conventional hollow fiber membranes.

[0183] In certain embodiments, the gas phase is N 2 , O 2 , CO 2 , C.H. 4 or a combination thereof. In some such embodiments, the liquid phase comprises liquid water. In certain currently preferred embodiments, the liquid phase is a water-based printing ink, or a water-based brine (e.g., a water-based well injection brine used in oil recovery).

[0184] In accordance with at least another embodiment of the present invention, a contactor system includes a liquid source, an air or gas source, at least one flat panel contactor including a plurality of asymmetric hollow fibers, and a rectangular frame, shell, housing, or vessel. The liquid source is preferably in fluid communication with the sheath of the hollow fibers. Air or gas is preferably passed over or across the fibers through the contactor.

[0185] Asymmetric hollow fiber membrane contactors may be used for many purposes, including but not limited to, removing entrained gas from liquids, degassing liquids, filtering liquids, and adding gas to liquids. More specifically, asymmetric hollow fiber membrane contactors may be advantageously used in removing entrained gas from inks used in printing.

[0186] In the gassing / degassing process, a continuous liquid / gas interface is created on the surface of the microporous fibers. In aqueous solutions, the liquid does not destroy the fibers due to the hydrophobicity and small pore size (50 nm to 100 nm) of polypropylene. The surface porosity allows for high-velocity gas transport across the fiber surface. However, typical hollow fiber membrane contactors can only process aqueous solutions.

[0187] In organic solvents or aqueous mixtures of water with high proportions (e.g., greater than 50 wt%, at least 60 wt%, 70 wt%, 80 wt%, or even 90 wt%) of organic solvent, wetting of the polyolefin pore walls is inevitable due to the low surface energy of the organic solvent and the polyolefin. Under such process conditions, hollow fiber membrane contactors may fail due to liquid collapse.

[0188] One approach to degassing organic solvents is the use of asymmetric hollow fibers containing a PDSP copolymer skin disposed on a porous polyolefin substrate. The thin, non-porous skin layer prevents collapse of the liquid while maintaining substantial gas permeability.

[0189] Asymmetric hollow fiber membrane contactors according to the present disclosure may also provide a means to achieve gas / gas, gas / liquid, and liquid / liquid (which may include liquid / dissolved solids) separation, transfer, or addition. Membrane contactors are typically used to bring two immiscible fluid phases, e.g., a first liquid and a second liquid, or a gas and a liquid, into contact with each other to separate and / or transfer one or more components from one fluid to the other.

[0190] The operation of the present disclosure will be further described with reference to the following detailed examples. These examples are provided to further illustrate various specific preferred embodiments and techniques. However, it should be understood that many variations and modifications can be made while remaining within the scope of the present disclosure. EXAMPLES

[0191] These examples are merely illustrative and are not intended to unduly limit the scope of the appended claims. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the present disclosure are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. At the very least, each numerical parameter should be construed by at least applying ordinary rounding techniques in light of the number of reported significant digits, but this is not intended to limit the application of the doctrine of equivalents to the scope of the claims.

[0192] Material Summary Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and elsewhere in the specification are by weight. In the comparative examples and examples below, the following materials are used: Polypropylene PPH3271, Total Petrochemicals USA, Inc. (Houston, Texas); PMP-polyolefin copolymer resin DX470, Mitsui Chemical (Minato-Ku, Tokyo, Japan); PMP-polyolefin copolymer resin MX002, Mitsui Chemical (Minato-Ku, Tokyo, Japan); PDSP15K, a polydiorganosiloxane polyoxamide copolymer (15 kDa weight average molecular weight for the organosiloxane blocks), prepared according to Example 16 of U.S. Pat. No. 7,501,184, the entire disclosure of which is incorporated herein by reference in its entirety. KAPTON Film tape, 3M Company (St Paul, MN); 1 / 4” nylon tubing, Grainger, Inc. (Minooka, IL); DP100 epoxy adhesive, Scotch-Weld DP100 Plus Clear, 3M Company (St Paul, MN); CO 2 pure gas, Oxygen Service Company (St. Paul, MN); N 2 Pure gas, Oxygen Service Company (St. Paul, MN).

[0193] Test Method The following test methods were used in evaluating some of the embodiments of the present disclosure.

[0194] Gas Permeability Test: The gas permeability test is used as an integrity test for the non-porous skin layers as well as a performance test for the hollow fiber membranes.

[0195] Loop modules were prepared by sealing the hollow fibers together with ¼” OD nylon tubing using DP100 epoxy adhesive. After at least partial curing, the fiber lumen was exposed by cutting the sealing tube with a razor blade. Each loop module contained 10 fibers with an effective length of 4”.

[0196] Gas permeability testing was performed using a custom designed test stand. The stand contained a pure gas (CO 2 and N 2 The fiber loop modules were equipped with a 1000 psi (1.0 psi) cylinder, a pressure gauge, and an in-line gas flow meter. The principle of the test is to supply pure gas to the fiber lumen and measure the rate at which the gas escapes through the fiber wall to the surrounding environment. Both gas pressure and gas flow are monitored by data acquisition software, and data is acquired when both pressure and gas flow have stabilized. Gas pressure in the fiber lumen was typically set at approximately 30 psi. Each fiber loop module was fitted with a CO 2 and N 2 Each was tested.

[0197] The gas permeability (GPU) of each fiber membrane was calculated as follows:

number

[0198] Textile CO 2 / N 2 Selectivity was calculated from the gas permeation rate of each gas using the following formula:

number

[0199] Fiber gas selectivity has been used as an indicator of skin integrity. PMP selectivity typically ranges from 11 to 13 according to literature reports (Polymer, 1989, 30, 1357). Silicone gas selectivity is 10 to 12 (Journal of Membrane Science, 1991, 55, 131). Any fiber with a gas selectivity below 8 was considered to have a defective skin.

[0200] Optical microscopy The hollow fiber membrane precursors were embedded in epoxy adhesive (DP100 Plus) and cut into short stubs (<5 mm) after curing. The embedded precursors were visualized under an optical microscope (Carl Zeiss "AXIO" stereo microscope, Pleasanton, CA) to measure the fiber OD, fiber wall thickness, and individual layers.

[0201] Scanning Electron Microscope (SEM) Testing Fiber samples were filleted with a razor blade to expose the inner surface and then imaged by a Phenom Desktop SEM (NanoScience Instruments Company, AZ).

[0202] Apparatus and method Apparatus for producing coextruded hollow fiber membranes The bilayer hollow fiber membrane precursors were coextruded through a two orifice annular ring die with a central air hole (custom-designed coextrusion die) using two Haake single screw extruders available from ThermoFisher Scientific (Grand Island, NY). The substrate resin was extruded through the central core of the die and the skin layer resin was extruded through the annular rings of the die.

[0203] After exiting the die, the molten hollow fibers were solidified through a quench ring and the hollow fiber membrane precursor was collected by passing it over motor-driven godet rollers and winding it onto a tension-controlled spooler.

[0204] Co-extrusion hollow fiber membrane manufacturing process Hollow fiber membrane precursor extrusion molding The skin layer resin (e.g., PDSP 15K) and the porous substrate resin (e.g., PPH 3721) were fed into two single screw extruders. The porous substrate resin was extruded using a 3 / 4" (1.91 cm) extruder with 24 L / D, and the skin layer resin was extruded using a 1 / 2" (1.27 cm) extruder with a smaller output. The three-zone porous substrate resin extruder was controlled at temperatures ranging from 200°C to 260°C from zone 1 to zone 3, while the three-zone skin layer extruder was controlled at temperatures ranging from 220°C to 250°C in zones 1 to 3. The extrusion die temperature was set at 220°C to 260°C.

[0205] The two melt resin streams were metered by pumps into a two orifice die (custom-designed coextrusion die) with a central air hole. The two melt streams converge inside the die at a distance of <5 mm from the die face. To ensure uniformity of the walls and layers of the bilayer hollow fiber membrane, the orifices in the die were fine-tuned to maintain good concentricity. The extrusion rate of the skin layer resin was kept significantly lower than that of the substrate resin to reduce the skin layer thickness.

[0206] A low volume air flow was supplied to the central hole to prevent the fibers from collapsing or being blown down. The molten fibers were solidified by passing through an air quench ring. The diameter of the hollow fiber membrane precursor was controlled by drawing using a motor-driven godet roll. The drawing speed was set in the range of 50 meters to 100 meters per minute. The resulting hollow fiber membrane precursor was collected using a low tension spooler.

[0207] Hollow fiber membrane annealing A 10" (25.4 cm) hollow fiber membrane precursor bundle was fabricated and each end was taped together using high temperature tape. The bundle was annealed in a convection oven set at a temperature of 140°C to 160°C. The annealing time for each fiber membrane precursor bundle was 10 minutes.

[0208] Hollow fiber membrane stretching (cold / hot) and heat curing Well-separated fiber bundles were clamped in the temperature-controlled environmental chamber of an Instron Mechanical Tester (Model #1122, Morwood, MA). The fibers were cold-stretched at 25°C-45°C and then hot-stretched at 120°C-150°C. The total elongation was 45%-105%. The fibers were held under tension during the temperature increase from low to high temperature. No fiber relaxation was observed after hot stretching. After the chamber temperature was cooled to below 40°C, the fibers were released from the Instron Mechanical Tester. The specific process conditions used in the examples and comparative examples are shown in Tables 1 and 2.

[0209] Comparative example A In Comparative Example A, PMP-PO(co)polymer / PMP-PO(co)polymer coextruded hollow fiber membrane, DX470 grade resin was used in the porous substrate, and MX002 grade resin was used in the skin layer to produce the coextruded hollow fiber membrane precursor. The process conditions are shown in Tables 1 and 2.

[0210] After annealing and stretching, the microporous hollow fiber membrane showed good CO 2 / N 2 Selectivity and CO up to 35.9 GPU 2 Both the gas flux and the pressure were measured.

[0211] [Table 1]

[0212] [Table 2]

[0213] [Table 3]

[0214] Examples 1 to 6 Coextruded hollow fiber membranes were produced using PDSP(15K) as the skin material and PPH3271 as the porous substrate material (Examples 1-3). PDSP is an AB diblock copolymer with silicone segments and polyoxamide linkages. The silicone segment molecular weight of PDSP 15K used in the examples is 15K Daltons. The PDSP / PP coextruded hollow fiber membranes in Examples 1-6 were processed similarly to the PMP / PMP coextruded hollow fiber membrane of Comparative Example A, except that different materials were used for both the skin layer and the porous substrate layer, and various process conditions were used.

[0215] The process conditions for these membranes are shown in Tables 1 and 2, and the membrane compositions are shown in Table 3. It is noted that the PDSP skin became sticky under high temperature annealing and hot stretching. The hollow fibers need to be well separated to prevent them from sticking to each other during processing. As a result, defects in the fiber skin can be avoided.

[0216] In Example 1, the PP substrate was extruded at 260°C in both the melt stream and the extrusion die. The substrate melt stream had a similar processing temperature as the skin melt stream. The PDSP / PP coextruded hollow fiber membrane was 2 / N 2 While the selectivity is below 8 (considered the threshold for indicating good skin integrity), excellent CO 2 The gas flux (693 GPU) was obtained.

[0217] In Examples 2-3, the PP substrate was extruded at 220°C in both the melt stream and extrusion die while the substrate melt stream was maintained at the same processing temperature as that of Example 1. The PDSP / PP co-extruded hollow fiber membrane precursor in Example 3 was wound at a faster speed than the precursor in Example 2. The fiber membrane precursor obtained in Example 3 has a smaller outer diameter, as shown in Table 1.

[0218] Figure 4A shows a visual image of the hollow fiber membrane precursor in Example 2. The PDSP skin was uniformly located on top of the PPH3271 substrate. Figure 4B provides a second image of the non-porous PDSP copolymer skin on the porous PPH3271 substrate after dry stretching the hollow fiber membrane precursor. As can be seen, the PDSP skin is substantially free of defects and pores.

[0219] By changing these process conditions, both the annealed and stretched PDSP / PP coextruded hollow fiber membranes showed excellent CO 2 Gas flux of 1000 m and good CO 2 / N 2 In particular, the membrane in Example 3 provided both a CO 2 The gas flux is 21 times higher than that of the PMP / PMP coextruded hollow fiber membrane in Comparative Example A.

[0220] In Examples 4-6, the PP substrate was extruded in the melt stream at 260°C with various substrate melt pump outputs, while the coextrusion die was controlled at 220°C. The processing conditions for the skin layer PDSP remained the same. Two interesting findings were observed from this set of experiments. First, the CO2 emission of the coextruded hollow fiber membranes in Examples 4-6 was significantly improved compared to the membrane in Example 1 by controlling only the coextrusion die temperature. 2 / N 2 Second, increasing the substrate melt pump output dramatically improved the gas selectivity. 2 No change in gas flux was observed, which means that the skin layer is the determining factor for gas flux in coextruded hollow fiber membranes.

[0221] Both the PDSP / PP coextruded hollow fiber membrane precursor and the membrane in Example 4 were analyzed by optical microscopy and scanning electron microscopy. The images are shown in Figures 2-4. Figure 2 is a cross-sectional view of the PDSP / PP coextruded hollow fiber membrane precursor. The elliptical shape of the fiber membrane precursor was caused by the sample preparation. This fiber membrane precursor shows a PDSP layer thickness of 8.3 um and a PP substrate layer thickness of 26.0 um. Figure 4C is a cross-sectional view of the hollow fiber membrane after annealing and stretching. Interestingly, stretching the coextruded hollow fiber caused little change in the thickness of the substrate layer (28.9 μm). However, while maintaining a solid dense film, the skin layer had a dramatic change in thickness, changing from 8.3 μm to 2.6 μm in thickness.

[0222] Without being bound to any particular theory, it is believed that the dry stretching process creates micropores in the substrate layer, which subsequently expands the material volume along the fiber direction, decreasing the density of the substrate layer. As a result, the dimensions across the fiber direction can remain consistent. In contrast, since no pores are created, conservation of mass or volume is applied to the skin layers. The elongation in the fiber direction can be compensated for by the reduced skin layer thickness.

[0223] This thinning of the skin is beneficial for improving membrane gas flux by controlling its thickness. The pore morphology of the PP substrate layer was further confirmed by imaging the intrafiber surface (Figure 4C). A typical dry-stretched membrane pore morphology is seen in the substrate layer with well-oriented lamellae and micropores between separated lamellae.

[0224] Throughout this specification, references to "one embodiment," "a particular embodiment," "one or more embodiments," or "an embodiment" mean that the particular feature, structure, material, or characteristic described in connection with that embodiment is included in at least one of the particular exemplary embodiments of the disclosure, regardless of whether the term "embodiment" is preceded by the term "embodiment." Thus, the appearances of phrases such as "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in an embodiment" in various places throughout this specification do not necessarily refer to the same particular exemplary embodiments of the disclosure. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0225] Although some exemplary embodiments have been described in detail herein, it is understood that those skilled in the art can easily imagine modifications, variations, and equivalents of these embodiments after understanding the above description. Therefore, it should be understood that the present disclosure is not unduly limited to the exemplary embodiments described so far. In particular, as used herein, the recitation of numerical ranges by endpoints is intended to include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5). In addition, all numbers used herein are intended to be modified by the term "about."

[0226] Furthermore, all publications and patents referenced in this specification are incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference. Various exemplary embodiments have been described. These and other embodiments are within the scope of the following claims.

Claims

1. An asymmetric hollow fiber membrane, an artificial semi-permeable barrier in the form of an open tubular filament, said barrier comprising: A porous substrate having a plurality of pores surrounding a lumen, the porous substrate comprising at least one semi-crystalline thermoplastic polyolefin (co)polymer; a skin layer covering the porous substrate; The skin layer comprises at least two repeat units of formula I: 【Chemistry 1】 [In the formula, Each R １ is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is a divalent group, R ３ is hydrogen or alkyl, or R ３ together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 1 to 1500; p is an integer from 1 to 10; and q is an integer of 1 or more. wherein n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent of the polydiorganosiloxane polyoxamide copolymer.

2. The R １ 2. The asymmetric hollow fiber membrane of claim 1, wherein at least 50 percent of the groups are methyl.

3. each Y is an alkylene having 1 to 10 carbon atoms, a phenylene bonded to an alkylene having 1 to 10 carbon atoms, or a phenylene bonded to a first alkylene having 1 to 10 carbon atoms and a second alkylene having 1 to 10 carbon atoms; G is an alkylene, heteroalkylene, arylene, aralkylene, polydiorganosiloxane, or a combination thereof; R ３ The asymmetric hollow fiber membrane of claim 1 , wherein is H or methyl.

4. 2. The asymmetric hollow fiber membrane of claim 1, wherein n is at least 40.

5. 2. The asymmetric hollow fiber membrane of claim 1, wherein the porous substrate comprises a luminal surface of the asymmetric hollow fiber membrane.

6. 2. The asymmetric hollow fiber membrane of claim 1, wherein the skin layer comprises an outer sheath surface of the asymmetric hollow fiber membrane.

7. 2. The asymmetric hollow fiber membrane of claim 1, wherein the skin layer comprises a luminal surface of the asymmetric hollow fiber membrane.

8. 2. The asymmetric hollow fiber membrane of claim 1, wherein the semi-crystalline thermoplastic polyolefin (co)polymer comprises polyethylene, polypropylene, polymethylpentene, or a combination thereof.

9. 2. The asymmetric hollow fiber membrane of claim 1, wherein the plurality of pores comprises a plurality of micropores, the plurality of micropores having a diameter from 0.01 micrometers to 1.0 micrometers.

10. 2. The asymmetric hollow fiber membrane of claim 1, wherein the asymmetric hollow fiber membrane exhibits a porosity of 5% to 80%.

11. 2. The asymmetric hollow fiber membrane of claim 1, wherein the skin layer is less porous than the porous substrate and comprises an outer sheath surface of the asymmetric hollow fiber membrane.

12. 12. The asymmetric hollow fiber membrane of claim 11, wherein the skin layer is non-porous.

13. 2. The asymmetric hollow fiber membrane of claim 1, wherein the skin layer has a thickness of less than 20 micrometers.

14. 2. The asymmetric hollow fiber membrane of claim 1, wherein the porous substrate has a thickness of from 5 micrometers to 200 micrometers.

15. 13. A separation article comprising a plurality of the asymmetric hollow fiber membranes of claim 1 arranged in a substantially parallel array and fastened together.

16. 16. The separation article of claim 15, wherein the array is pleated, folded, or rolled into a cylinder or cassette.

17. The separation article is N ２ More than CO ２ In contrast, CH ４ More than CO ２ 16. The separation article of claim 15, which is selectively permeable to water vapor rather than to air, or to one or more volatile organic compounds rather than to air.

18. The separation article comprises at least 8 CO ２ / N ２ Or CO ２ / CH ４ 20. The separation article of claim 17, which exhibits selectivity.

19. 1. A method for producing an asymmetric hollow fiber membrane, comprising: A substrate resin and a skin layer resin are provided, the substrate resin comprising at least one semi-crystalline thermoplastic polyolefin (co)polymer and the skin layer resin comprising at least two repeating units of formula I: 【Chemistry 2】 [In the formula, Each R １ is independently alkyl, haloalkyl, aralkyl, alkenyl, aryl, or aryl substituted with alkyl, alkoxy, or halo; each Y is independently an alkylene, an aralkylene, or a combination thereof; G is a divalent group, R ３ is hydrogen or alkyl, or R ３ together with G and the nitrogen to which they are both attached form a heterocyclic group; n is independently an integer from 0 to 1500; p is an integer from 1 to 10; and q is an integer of 1 or more. and optionally n, p, and q are selected such that the polydiorganosiloxane blocks comprise at least 50 weight percent of the polydiorganosiloxane polyoxamide copolymer; co-extruding the substrate resin and the skin layer resin to form an asymmetric hollow fiber membrane precursor; and stretching the asymmetric hollow fiber membrane precursor to form an asymmetric hollow fiber membrane having a substantially non-porous skin layer comprised of the skin layer resin overlying a porous substrate comprised of the base resin, the porous substrate comprising a plurality of pores.

20. 20. The method of claim 19, further comprising annealing the asymmetric hollow fiber membrane precursor.

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