Polymers for gas separation membranes

Abstract

The present disclosure relates to gas separation membranes which may be used for separating carbon dioxide from a gas stream. Methods for separating carbon dioxide from a gas stream using these membranes are also provided.

Description

[0001] POLYMERS FOR GAS SEPARATION MEMBRANES

[0002] Inventors: Yuta Takenouchi, Brett T. Harding, Weiping Lin, Isamu Kitahara

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims priority to U.S. Provisional Application No. 63 / 571,363, filed March 28, 2024, and U.S. Provisional Application No. 63 / 663,684, filed June 24, 2024, which are incorporated by reference in their entirety.

[0005] Field

[0006] This disclosure relates to a polymer which may be used in gas separation membranes.

[0007] Description of the Related Art

[0008] Membranes for separation of gases in a gas mixture, known as gas separation membranes, are based on the physical and / or chemical interaction of the gases in the gas mixture with the membrane material. A wide variety of gas separation membranes are known, and the use thereof frequently depends on the specific design of the membrane. For instance, the choice of membrane material may impact the membrane performance in terms of permeability and selectivity for specific gases, allowing some gases to pass through the membrane while others are prevented from passing through. Further, the membrane material may include pores and / or further components to provide a specific gas permeability.

[0009] Gas separation membranes are used in many diverse applications such as gas purification or recovery, air separation, natural gas sweetening, vapor recovery, separation of by-products, in oil and gas related industries, etc. Membrane separation technologies are considered as energy-efficient and compact solutions compared to conventional absorption-desorption technologies.

[0010] Traditional polymeric membranes have increased the commercial market for separations such as C ^and CO2 / CH4. These gas separation membranes include a polymer or mixture of polymers as membrane material and have been found to be economically and technologically useful. However, there is often a limit on their performance known as the Robeson limit, relating to a trade-off between selectivity and permeability. Mixed matrix membranes, such as polymeric membranes with inorganic fillers, may have improved properties compared to pure polymer membranes. However, providing gas separation membranes which maintain or increase selectivity and mechanical strength remains a challenge.

[0011] Thus, there is a need for additional contributions in this area of technology.

[0012] SUMMARY

[0013] In one or more embodiments, a polymer which may be used in gas separation membranes to remove a target gas from a media stream is provided. In some embodiments, a membrane including a polymer described herein may exhibit desired strength and desired gas selectivity. In some embodiments, a method for selectively removing carbon dioxide gas from a mixed media stream is provided.

[0014] In one embodiment, a graft copolymer includes a backbone of repeating units, at least a first polymeric side-chain which includes a polysiloxane, and at least a second polymeric side-chain which includes a polyether. The first polymeric side-chain accounts for about 3 wt% to about 50 wt% of the graft copolymer and the second polymeric sidechain accounts for about 97% wt% to about 50 wt% of the graft copolymer. In one or more forms, the backbone may include a polyacrylate, the first polymeric side chain may include an alkyl siloxane or a polydimethyl siloxane, and / or the second polymeric side chain may include a polyethylene glycol.

[0015] In some forms, the graft copolymer may be according to the following formula (1): (Formula I)

[0016] In Formula (1), each of m and n2 is an integer greater than or equal to 1 , x is the first polymeric side chain and y is the second polymeric side chain. In some forms, the graft copolymer may further include a third polymeric side-chain When present, the third polymeric side chain may include at least one of acrylamide, a vinylimidazole, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, 5-oxotetrahydrofuran-3-yl methacrylate, glycidyl methacrylate, and polyethylene glycol diacrylate.

[0017] In another form, the graft copolymer may be according to the following formula (2):

[0018] (Formula 2).

[0019] In Formula (2), each of m and n2 is an integer greater than or equal to 1 , the first sidechain (x) may account for about 2 wt% to about 40 wt% of the graft copolymer; the second side-chain (y) may account for about 60 wt% to about 98 wt% of the graft copolymer; and the third side-chain (z) may account for about 0.1 wt% to about 5 wt% of the graft copolymer.

[0020] In yet another form, the graft copolymer may be according to the following formula (3): (Formula 3). In Formula (3), each of m and n2 is an integer greater than or equal to 1 , the first sidechain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer; the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer, and the third side-chain (z) accounts for about 0.1 wt% to about 38 wt% of the graft copolymer.

[0021] In still another, the graft copolymer may be according to the following formula (4):

[0022] (Formula 4)

[0023] In Formula (4), each of m and n2 is an integer greater than or equal to 1 , the first sidechain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer, the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer, and the third side-chain (z) accounts for about 0.1 wt% to about 38 wt% of the graft copolymer.

[0024] In another form, the graft copolymer may be according to the following formula (5): (Formula 5)

[0025] In Formula (5), each of m and n2 is an integer greater than or equal to 1 , the first side- chain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer, the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer, and the third side-chain (z) accounts for about 0.1 wt% to about 38 wt% of the graft copolymer.

[0026] In some forms, the polyether of the second polymeric side-chain may include at least one of polyoxyethylene methyl ether methacrylate monomer (POEM) and PEG methyl ether acrylate (PEGMEA). In another embodiment, a casting solution includes a graft copolymer as described herein and a polyethylene glycol diacrylate. In another embodiment, a membrane includes a graft copolymer as described herein. In another embodiment, a gas separation membrane includes a graft copolymer as described herein. In some forms, the gas separation membrane may provide CO2 gas selectivity over IX^ gas. In one embodiment, a membrane includes a porous substrate, a first layer including a silicon containing polymer, and a gas selective layer including a graft copolymer described herein. In some forms, the gas separation membrane may further include a polysiloxane protective layer, and the polysiloxane protective layer may be disposed upon the gas selective layer.

[0027] In another embodiment, a method for making a gas membrane includes providing a graft copolymer including a backbone of repeating units, at least a first polymeric sidechain which includes a polysiloxane, and at least a second polymeric side-chain which includes a polyether. The first polymeric side-chain accounts for about 3 wt% to about 40 wt% of the sidechain polymers and the second polymeric side-chain accounts for about 97% wt% to about 60 wt% of the total weight of the side-chain polymers. The method further includes creating a casting solution including the graft copolymer, casting the casting solution onto a substrate to form a film, and annealing the film to form a gas membrane. In some forms, the graft copolymer may further include a third polymer sidechain, and the third side-chain may account for about 38 wt% of the graft copolymer. In some forms, the third polymer side-chain may include polyethylene glycol diacrylate, a vinylimidazole, tetrahydrofurfuryl methacrylate, or acrylamide.

[0028] These and other embodiments are described in greater detail below.

[0029] BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Fig. 1 is a schematic illustration of a gas separation membrane.

[0031] Figs. 2 and 3 are 1 H nuclear magnetic resonance spectra of a polymer described herein.

[0032] Fig. 4 is a schematic illustration of an apparatus for testing gas selectivity.

[0033] FIG. 5 is bar graph showing the gas selectivity of membranes with different polymers described herein.

[0034] DETAILED DESCRIPTION

[0035] For purposes of promoting an understanding of the present disclosure, reference will now be made to the following embodiments and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended, such alterations and further modifications in the described subject matter, and such further applications of the disclosed principles as described herein being contemplated as would normally occur to one skilled in the art to which the disclosure relates. As used herein, the term “graft copolymer” refers to the copolymers and terpolymers described herein. A “graft copolymer” may include forms where each monomer includes a polymeric side-chain, i.e. each monomer may be a macromonomer, and may also include forms including a polymerization product of multiple (i.e. two or more) distinct macromonomers and one / or more distinct small molecule monomers.

[0036] In one embodiment, a graft copolymer for use in selective gas separation membranes may be provided. Other embodiments relate to a casting solution including a graft polymer as described herein. In some forms, the casting solution may include polyethylene glycol diacrylate. Other embodiments relate to a gas separation membrane including a graft copolymer as described herein. In another embodiment, a method for making a gas separation membrane including a graft copolymer described herein is provided. Further embodiments relate to a method for selectively removing carbon dioxide from a media stream. In some embodiments, a gas separation membrane may provide CO2 selectivity over N2.

[0037] In one embodiment, a graft copolymer includes a backbone of repeating units, at least a first polymeric side-chain and at least a second polymeric side-chain. The first polymeric side-chain may include one or more of a polysiloxane, a polysiloxane anologue, a silicon-containing polymer, a polyalkylsiloxane, and polydimethyl siloxane, and the second polymeric side chain may include a polyether. In some forms, the graft copolymer may further include a third polymeric side-chain which may include one or more of acrylamide, a vinylimidazole, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, 5-oxotetrahydrofuran-3-yl methacrylate, glycidyl methacrylate, and polyethylene glycol diacrylate. In some forms, the first polymeric side-chain may account for about 3 wt% to about 40 wt% of the graft copolymer, the second polymeric side-chain may account for about 97% wt% to about 60 wt% of the graft copolymer, and the third side-chain may account for about 0.1 wt% to about 40 wt% of the graft copolymer.

[0038] In one embodiment, a graft copolymer includes a backbone of repeating units. In some forms, the backbone of repeating units may include a chain of carbon-carbon bonds. In some forms, the backbone may include a homopolymer, copolymer or terpolymer of a polyacrylate, a polymethyacrylate and / or a polyvinyl such as polyacrylate.

[0039] In some forms, the first polymeric side-chain may be a pendant side-chain and / or may be covalently bound to the backbone. In some forms, the first polymeric side-chain may be linked to the backbone by an alkyl group, non-limiting examples of which include a C2 to C5 alkyl group such as a C3 alkyl group. In some forms, the first polymeric sidechain may include a soft monomer. In some forms, the first polymer side chain may include an alkyl siloxane such as a polyalkyl siloxane or polydimethyl siloxane (PDMS) and / or any analogue or salt thereof, although other variations are possible and contemplated. In some forms, the first polymeric side-chain (e.g., PDMS) may have a molecular weight in the range of 1 ,000 to 10,000 grams per mole. While not wanting to be bound by theory, it is believed that if the molecular weight is too high, it may be difficult to polymerize. If the molecular weight is too low, it may provide insufficient coating properties on the substrate, and it could result in becoming damaged by applying a protective layer upon it. Amongst other things, where the first polymeric side chain is a PDMS side chain it may provide increased compatibility and / or adherence to a substrate (“gutter layer”) that includes some PDMS or to a protective layer topcoat that includes some PDMS. Further, while not wanting to be bound by any particular theory, it is believed that PDMS may be difficult to coat with hydrophilic polymers. Conversely, it is believed that hydrophilic polymers may not contain enough PDMS and may be difficult to coat with silicones PDMS also imparts a high gas permeability to the layer, and may naturally allow a high gas transport property. If PDMS content is too small, the gas permeance or gas permeability may be too low. This relates not just to the PDMS chain length of the macromonomer, but also the total weight amount of PDMS (grams of PDMS per gram of polymer). In some forms, the first polymer side-chain may account for about 2.0 wt%, about 2.5 wt%, about 3 wt%, about 4 wt%, about 5 wt%, about 8 wt%, about 10 wt%, about 15 wt%, about 20 wt%, about 25 wt%, about 33 wt%, or about 40 wt% or any range of values bound by the foregoing (e.g., 10-20 wt%) of the weight of the graft copolymer, and / or the weight of the polymeric side-chains of the graft copolymer

[0040] In some forms where the first polymeric side chain is a polymeric PDMS sidechain, it may have a molecular weight which is greater than about 100 g / mol, about 4000 g / mol, or about 9000 g / mol, just to provide a few possibilities. In some forms where the first polymeric side chain is a polysiloxane side chain, it may have a molecular weight from about 500 to about 7500, about 8000, about 9000, about 10,000, about 11 ,000, or about 12,500 grams per mole and / or any permutation of the aforementioned values, e.g., about 5,000 to about 10,000 grams per mole. In some forms In some forms where the first polymeric side chain is a polymeric PDMS side-chain, the total weight amount of PDMS may be about 2.0%, about 5.0%, about 7.5 %, about 8.0%, about 10.0%, or about 12.5% to about 15%, about 17.5%, about 20.0%, about25%, or about 30% of the weight of the side chain including the PDMS and polymer, and / or any permutation of the aforementioned values, e.g., about 0.1 to about 0.2 grams PDMS per gram of polymer. While not wanting to be bound by any particular theory, it is believed that too low a mass percentage of polysiloxane in the graft copolymer may reduce the gas permeability below desired levels, e.g., below 1000 GPU. Further, it is believed that below a certain threshold of PDMS content, e.g. below about 3 wt%, the surface properties of the polymer layer (such as the water contact angle for example) become unsuitable for forming a defect- free polysiloxane protective layer on top of it. In some forms, it is believed that increasing levels of PDMS beyond a certain limit, e.g. above about 30 wt%, may cause a reduction in the selectivity of CO2 gas over N2 gas.

[0041] T urning now to the second polymeric side-chain, it may be covalently bound to the backbone. In some forms, the second polymeric side-chain may be linked to the backbone by an alkyl group such as a C2 to C5 alkyl group, e.g., a C3 alkyl group. In some forms, the second polymeric side chain may include a polyether such as a polyoxyethylene methyl ether methacrylate monomer (POEM) having a molecular weight between about 500 and about 950 and / or a polyethylene glycol monomethyl ether acrylate (PEGMEA) having a molecular weight of about 480. In some forms, the second polymeric side-chain may include polyethylene glycol, such as polyethylene glycol monomethyl ether. In forms where the second polymeric side-chain includes a polyether it may have a molecular weight between about 150 g / mole to about 600 g / mol, about 750 g / mol, about 900 g / mol, about 1000 g / mol, about 1500 g / mol, and / or about 2000 g / mol or any permutation of these ranges, e.g., about 300 to about 1000 g / mol. In some forms, the total weight of the polyether may be about 98%, about 97%, about 90%, about 88%, about 85%, about 80%, about 78%, about 75%, about 70%, about 65%, about 60%, about 55% and / or about 50% by weight of the graft copolymer and / or the total weight polymer side-chains, or any permutation of the aforementioned values, e.g. about 0.7 to about 0.9 grams of polyether per gram of graft copolymer. While not wanting to be bound by any particular theory, it is believed that if a polyethylene glycol (PEG) side chain is too short the selectivity of a membrane including the graft copolymer for CO2 over N2 transport may be too low since the overall content of the polyether would be undesirably reduced. It is further believed that if a polyether side chain is too short, the polyether chains may not be sufficiently interconnected throughout the body of the selective layer resulting in a poorly defined diffusion path for CO2 gas transport and undesirable reduced permeance and selectivity. If the polyether side chain is too long, the polyether chains may tend to be too crystalline which may reduce the gas permeance of the membrane. In some forms, the gas permeability of the gas selective layer including a graft copolymer described herein may be greater than about 300 gas permeation units (GPU) (1 GPU = 10"6cm3(STP) / (cm2s cm Hg)), greater than about 500 GPU, greater than about 800 GPU, greater than about 1 ,000 GPU, greater than about 2,000 GPU, greater than about 3,000 GPU, greater than about 5,000 GPU, greater than about 7,000 GPU, or greater than about 10,000 GPU. In some forms, the gas permeability of the gas selective layer including a graft copolymer described herein may be between about 500 GPU and about 5,000 GPU.

[0042] In some forms, the graft copolymer may include a third polymeric side chain, and the third polymeric side-chain may be covalently bound to the backbone. In some forms, the third polymeric side-chain may be linked to the backbone by an alkyl group such as a C2 to C5 alkyl group, e.g., a C3 alkyl group. In some forms, the third polymeric side-chain may be a cross-linker. In some forms, the third side chain may include a glassy monomer, a hard monomer, a crosslinker, and / or a polyethylene glycol diacrylate (PEGDA). When the polyethylene glycol diacrylate is present, it may have a molecular weight from about 50 g / mol, about 75 g / mol, about 100 g / mol, about 200g / mol to about 10,000 g / ml, about 15000 g / mol, about 40,000 g / mol, about 50,000 g / mol, about 75,000 g / mol, and / or about 100,000 g / mol or any permutation of the aforementioned values, e.g., about 100 g / mol to about 40,000 g / mol. In some forms, the third polymeric side-chain may include one or more of a polyethylene glycol diacrylate having molecular weight from about 400 grams per mole to about 40,000 grams per mole, acrylamide (AcAm), glycidyl methacrylate (GMA), tetrahydrofurfuryl methacrylate (THFMA), tetrahydrofurfuryl acrylate (THFA), a vinyl imidazole, N-vinyl imidazole (Vim), and 5-oxotetrahydrofuran-3-yl-methacrylate (OXOTHFMA, 5-OxoTHFMA). In some forms, the total weight amount of the third side chain may account for about 0.1%, about 1%, about 2%, about 4%, about 5%, about 8%, about 10%, about 12%, about 15%, about 20%, about 22%, about 25%, about 30%, about 38%, or about 40% of the total weight of the graft copolymer or the total weight of the polymeric side-chains and / or any permutation of the aforementioned ranges, e.g., about 0.01 to about 0.2 grams of the third side chain per gram of graft copolymer. While not wanting to be bound by any particular theory, it is believed that the inclusion of a third side chain may impart certain characteristics to the graft copolymer such as improved mechanical strength, elasticity, ease of solubility and processing, viscosity control, improved interlayer compatibility in multilayer membranes, improved film forming characteristics, enhanced selectivity and / or permeance of carbon dioxide transport, enhanced microphase domain separation leading to higher gas permeance and / or selectivity of gas transport.

[0043] In some forms, the graft copolymer may be according to the following formula (1):

[0044] Formula (1)

[0045] In Formula (1), x and y represent the relative mole fractions of each macromonomer in the graft copolymer; e.g. x + y = 1 , and each of m and n2 independently represents the average number of repeating units according to the number average molecular weight or Mnof the respective macromonomer and are each independently an integer greater than or equal to 1.

[0046] In some forms, the graft copolymer may be according to the following formula (2):

[0047] In Formula (2), x, y, and z represent the relative mole fractions of each monomer or macromonomer in the graft copolymer, e.g. x + y + z = 1 , and each of ni, n2, and ns independently represents the average number of repeating units according to the number average molecular weight or Mnof the respective macromonomer and are each an integer greater than or equal to 1. In some forms, x may be from about 0.0005 to about 0.6, y may be from about 0.997 to about 0.4, z may be from about 0.001 to about 0.05, may be from about 2 to about 200, n2 may be from about 2 to about 50, and ns may be from about 2 to about 1000. In one particular but non-limiting form, x is 0.0133, y is 0.9697, z is 0.0172, ni is 64, n2 is 9, and ns is 10. In some forms, the values of x, y, z, ni, n2, and ns are selected such that their combination results in a mass percentage content of PDMS of about 2% to about 40% by weight of the overall graft copolymer, a mass percentage of polyether content of about 60% to about 98% by weight of the overall graft copolymer, and an amount of cross-linking monomers of about 0.1 % to about 5% by weight of the overall graft copolymer. In some forms, the first side-chain (x) may account for about 2 wt% to about 40 wt% of the graft copolymer; the second side-chain (y) may account for about 60 wt% to about 98 wt% of the graft copolymer; and the third side-chain (z) may account for about 0.1 wt% to about 5 wt% of the graft copolymer.

[0048] In some forms, the graft copolymer may be according to the following formula (3): Formula (3)

[0049] In Formula (3), x, y, and z represent the relative mole fractions of each monomer or macromonomer in the graft copolymer, e.g. x + y + z = 1 , and each of ni, and n2 independently represents the average number of repeating units according to the number average molecular weight or Mnof the respective macromonomer and are each independently an integer greater than or equal to 1 . In some forms, x may be from about 0.0005 to about 0.6, y may be from about 0.997 to about 0.2, z may be from about 0.8 to about 0.001 , ni may be from about 2 to about 200, and n2 may be from about 2 to about 50. In one particular but non-limiting form, x is 0.0082, y is 0.660, z is 0.332, n1 is 64, and n2 is 9. In another particular but non-limiting form, x is 0.0069, y is 0.7249, z is 0.2682, ni is 64, and n2 is 9. In still another particular but non-limiting form, x is 0.0026, y is 0.5295, z is 0.4679, ni is 64, and n2 is 9. In another particular but non-limiting form, x is 0.0118, y is 0.6954, z is 0.2928, m is 64, and n2 is 9. In yet another particular but non-limiting form, x is 0.0118, y is 0.5652, z is 0.4230, m is 64, and n2 is 9. In still another particular but nonlimiting form, x is 0.0095, y is 0.6329, z is 0.3576, m is 64, and n2 is 9. In some forms, the values of x, y, z, m , and n2 are selected such that their combination results in a mass percentage content of PDMS of about 2% to about 40% by weight of the overall graft copolymer, a mass percentage of polyether content of about 60% to about 98% by weight of the overall graft copolymer, and a mass percentage of the third side-chain of about 0.1 % to about 40% by weight of the overall graft copolymer. In some forms, the first side- chain (x) may account for about 2 wt% to about 40 wt% of the graft copolymer; the second side-chain (y) may account for about 60 wt% to about 98 wt% of the graft copolymer; and the third side-chain (z) may account for about 0.1 wt% to about 38 wt% of the graft copolymer.

[0050] In some forms, the graft copolymer may be according to the following formula (4): Formula (4)

[0051] In the Formula (4), x, y, and z represent the relative mole fractions of each monomer or macromonomer in the graft copolymer, e.g. x + y + z = 1 , and each of and n2 independently represents the average number of repeating units according to the number average molecular weight or Mnof the respective macromonomer and are each independently an integer greater than or equal to 1. In some forms, the first side-chain (x) may account for about 2 wt% to about 40 wt% of the graft copolymer; the second sidechain (y) may account for about 60 wt% to about 98 wt% of the graft copolymer; and the third side-chain (z) may account for about 0.1 wt% to about 38 wt% of the graft copolymer.

[0052] In some forms, the graft copolymer may be according to the following formula (5): Formula (5)

[0053] In Formula (5), x, y, and z represent the relative mole fractions of each monomer or macromonomer in the graft copolymer, e.g. x + y + z = 1 , and each of ni, and n2 independently represents the average number of repeating units according to the number average molecular weight or Mnof the respective macromonomer and are each independently an integer greater than or equal to 1. In some forms, the values of x, y, z, ni, and n2 are selected such that their combination results in a mass percentage content of PDMS of about 2% to about 40% by weight of the overall graft copolymer, a mass percentage of polyether content of about 60% to about 98% by weight of the overall graft copolymer, and a mass percentage of the third side-chain of about 0.1% to about 40% by weight of the overall graft copolymer. In some forms, the first side-chain (x) may account for about 2 wt% to about 40 wt% of the graft copolymer; the second side-chain (y) may account for about 60 wt% to about 98 wt% of the graft copolymer; and the third side-chain (z) may account for about 0.1 wt% to about 38 wt% of the graft copolymer.

[0054] As schematically illustrated in FIG. 1 , a gas separation membrane 10 includes a porous substrate or support layer 12, a first layer (gutter) layer 14, a gas selective membrane 16, and a protective layer 18. In some forms, the gas selective membrane 10 may include a graft copolymer as described herein. In some forms, the first or gutter layer 14 may be disposed upon, layered upon and / or contacted with the porous substrate 12. Further, the gas selective membrane 16 may be disposed upon, layered upon and / or contacted with the first or gutter layer 14. The protective layer 18 may be disposed upon, layered upon and / or contacted with the gas membrane 16. In some forms, the first or gutter layer 14 may include a silicon containing polymer such as a siloxane. A more particular example of the siloxane includes a polyalkyl siloxane. In some forms, the polyalkyl siloxane may be PDMS, and / or a PDMS acrylate.

[0055] In some forms, the porous substrate or support layer 12 may be produced by a phase inversion method. In some forms, the porous substrate or support layer 12may exhibit a pore size from about 10nm to about 5000nm. In some forms, the pore size can be about 200nm. The porous substrate or support layer 12 may exhibit a pore size distribution that is typical of porous membranes used for ultrafiltration, nanofiltration, reverse osmosis, and the like. In some forms, the thickness of the porous substrate or support layer 12may be from about 10 microns to about 300 microns. In some forms, the porous substrate or support layer 12 may have a gas permeability of greater than about 3,000 gas permeation units (GPU) (1 GPU = 10"6cm3(STP) / (cm2s cm Hg)), about 5,000 GPU, about 7,000 GPU, about 10,000 GPU, or about 20,000 GPU. By way of example, porous substrate or support layer 12 may include one or more of polysulfone (PSf), poly(ether sulfone), polyvinylidene difluoride (PVDF), polytetrafluoroethylene (PTFE), a perfluoropolymer, a partially fluorinated polymer, polyacrylonitrile (PAN), a polyvinylamide, polyurethane (PU), a polyurea, polydimethylsiloxane (PDMS), polyethylene, polypropylene, poly(ethylene terephthalate) (PET) and polyimide. In one particular but non-limiting form, the porous substrate or support layer 12 may include a polysulfone-coated PET porous sheet.

[0056] The membrane 10 may include a siloxane and / or silicone layer. In some forms, the first layer 14 may include a siloxane. In some forms, the first layer 14 may include PDMS. In some forms, the first layer 14 may include a siloxane homopolymer. In some forms, the first layer 14 may be a gutter layer. While not wanting to be bound by any particular theory, it is believed that insertion of a first layer 14, e.g., a gutter layer, between the porous substrate 12 and the gas selective membrane 16 increases adherence of the gas selective membrane 16 to the porous substrate 12. Further, it is believed that insertion of a gutter layer 14 between the porous substrate 12 and the gas selective membrane 16 may increase the efficiency of the membrane 10. In some forms, the gutter layer 14 may have a permeability greater than the gas selective membrane 16. In some forms, the gutter layer 14 may be a homopolymer layer, although other variations are possible and contemplated. In some forms, the gutter layer 14 may include at least poly (1-trimethyl-1-propyne) (PTMSP), polydimethyl siloxane (PDMS) and / or a silicone resin. In one form, the gutter layer may include a blend of PTMSP and / or PDMS and / or a silicone resin with at least one other polymer selected from polysulfone, poly(ether sulfone), polyvinylidene diflouroide (PVDF), polytetrafluoroethylene (PTFE), a perfluoropolymer, polyacrylonitrile (PAN), polyurethane (Pll), polyethylene, polypropylene, poly(ethylene terephthalate) (PET) and polyimide. In some forms, the gas selective membrane may include a first polymer side-chain that is at least 90% similar to a component of the gutter layer material 14. For example, if the gutter layer 14 includes PDMS, then the first polymer side-chain may include PDMS. While not wanting to be bound by any particular theory, it is believed that the coordination of such elements may increase attachment strength, shear strength at the gutter layer 14 and gas selective membrane 16 interface, and reduce the incidence of coating defects. In some forms, the gutter layer 14 may have a gas permeability of greater than about 1 ,000 GPU, about 3,000 GPU, about 5,000 GPU, about 7,000 GPU, or about 10,000 GPU.

[0057] In some forms, the gas selective membrane 16 may include a polymer matrix, and the polymer matrix may include a graft copolymer as described herein. By way of example, the polymer matrix may include a polyether, a polysiloxane, a block copolymer, and / or a surfactant. Non-limiting examples of a polyether include, but are not limited, to polyethylene glycol, polyethylene oxide, polypropylene glycol, polypropylene oxide, polydioxolane, polytetramethylene oxide, random copolymers of any of these, block copolymers of any of these, and the like. The protective layer 18 may include a silicone, and / or a polysiloxane such as polydimethyl siloxane (PDMS). In some forms, the protective layer 18 may have a gas permeation rate of at least about 500, about 750, about 1000, about 1250, about 2000, about 3000, about 5000, or about 10000 GPU. In some forms, the protective layer 18 may have a thickness of less than about 2000 nm, about 1000 nm, about 900 nm, about 800 nm, about 700 nm, about 600 nm, about 500 nm, about 400 nm, about 300 nm, about 200 nm, about 100 nm, or about 50 nm.

[0058] In some forms, the gas selective membrane 16 may provide a CO2 gas over N2 gas selectivity of greater than about 10, greater than about 15, greater than about 20, greater than about 25, greater than about 30, greater than about 35, or greater than 40, although other variations are possible. Those skilled in the art may recognize that the gas selective membrane 16 described herein may be useful for separation of other gases, e.g. gas separations involving methane, C1-C5 hydrocarbons, hydrogen, and others.

[0059] In one embodiment, a method for making a gas membrane includes providing a graft copolymer which includes a backbone of repeating units, at least a first polymeric side-chain which includes a polysiloxane such as PDMS, and at least a second polymeric side-chain which includes a polyether. The first polymeric side-chain may have a sidechain wt % of about 3 wt% to about 40 wt% of the total weight of the sidechain polymers and the second polymeric side-chain may have a side-chain wt% of about 97% wt% to about 60 wt% of the total weight of the side-chain polymers. The method also includes creating a casting solution having a solids content from 0.1 to about 5 wt% of the graft copolymer in a suitable solvent, casting the solution on top of a first or gutter layer to form a film of the casting solution, annealing or heating the film after casting forming a selective polymer layer, and forming a gas separation membrane. In some forms, the graft copolymer may include a third side-chain which includes at least one of acrylamide, a vinylimidazole, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, 5- oxotetrahydrofuran-3-yl methacrylate, and polyethylene glycol diacrylate. In some forms, the first polymeric side-chain may account for about 3 wt% to about 40 wt% of the graft copolymer, the second polymeric side-chain may account for about 97% wt% to about 60 wt% of the graft copolymer, and the third side-chain may account for about 0.1 wt% to about 40 wt% of the graft copolymer.

[0060] In a further embodiment, a method for removing carbon dioxide includes providing a media stream including carbon dioxide and from which carbon dioxide is to be removed, contacting and / or passing the carbon dioxide media stream over, through, and / or in contact with a membrane which includes a graft copolymer as described herein, and selectively retaining and / or dividing out or removing the carbon dioxide while passing the treated media stream.

[0061] EXAMPLES

[0062] Polymer Synthesis Procedures

[0063] Synthesis of Polymer-1

[0064] Step 1

[0065] Polymerization: A 3-liter, 3-neck round bottom flask was cleaned with ethyl acetate. Polyoxyethylene methyl ether methacrylate (CAS 26915-72-0, average Mn = 500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.) monomer (236.73 g, 78 wt%) was added to the flask. Monomethyacryloxypropyl terminated polydimethylsiloxane (Gelest, Inc., MCR- M17, 5000 g / mol, CAS 146632-07-7), monomer (60.7 g, 20 wt%) was also added to the flask. Polyethlylene glycol diacrylate (PEGDA575, Sigma-Aldrich, 437441 , CAS 26570- 48-9, average Mn = 575 g / mol), difunctional monomer (6.1 g, 2 wt%) was added. A large magnetic stir bar (63.5 x 19 mm, egg shape) was added. Ethyl acetate (1200 ml) was added. Azobisisobutyronitrile (AIBN, Sigma Aldrich Millipore, St. Louis, Mo) initiator (0.606 g, 0.2 wt%) was added. The flask was placed in a 3-liter aluminum heating block on a hotplate stirrer. The mixture was stirred at room temperature with a stirring speed of 600 RPM. An air-cooled condenser (Al fin type, Radleys, Findenser R010197) was attached to the center neck, and a temperature probe (OMEGA; Data logger, model no. OM-DAQ PRO-5300, Omega Engineering, Stamford CT, USA) was inserted into the solution through a Polytetrafluoroethylene (PTFE) stopper for temperature monitoring. The third neck of the flask and the condenser were sealed with a rubber septum. An inlet needle (stainless steel) carrying argon gas was inserted through the lower septum, and an outlet needle was inserted into the upper (condenser) septum to allow for streaming argon. The inlet needle was inserted into the solution to bubble argon for degassing. An hour later, the degassing needle was moved out of the solution, and remained in the head space of the flask. The hotplate was set to 82°C* with a time setting of 12 hours. The stirring rate was reduced to 300 RPM. Upon reaching the setpoint temperature, the outlet needle was removed, and the inlet needle continuously supplied a slight positive pressure of argon for the duration of the polymerization.

[0066] *The temperature setting of the hotplate with the 3L flask had previously been calibrated using the OMEGA temperature probe in pure ethyl acetate (1500 ml). During this calibration experiment, a hotplate temperature setting of 82 °C resulted in a stable solution internal temperature around 70.0-71.0 °C.

[0067] Precipitation and Purification: The reaction mixture was viscous but no gels could be visualized. An aliquot of the reaction mixture was diluted with CDCI3 and an 1 H nuclear magnetic resonance (HNMR) spectrum was obtained. Related results are illustrated in FIG. 3. Regarding the proton signal integrations, 91% of the monomers were consumed as evidenced by the relative integral of the alkene protons compared to the integral of the monomethyl ether protons. The reaction mixture was separated into three 500ml portions. Each of the three portions was precipitated separately by the following procedure steps:

[0068] 1) A stir bar (63.5 mm x 19 mm egg shaped) and 3.3 L of hexane were added into a 4-L conical flask and placed on top of a magnetic stirrer. The stirrer was set to 400 RPM.

[0069] 2) The 500 ml portion of reaction solution was poured into a 1-L separatory funnel (Chemglass) with a PTFE stopcock, and the funnel was clamped directly above the 4-L flask.

[0070] 3) The stopcock of the separatory funnel was opened to allow the reaction solution to be slowly added to the stirring hexane. Upon completion, residual reaction solution was rinsed into the hexane with a minimal quantity of ethyl acetate.

[0071] 4) After stirring for approximately 10-30 minutes, the suspension was transferred to 1-L centrifuge canisters (polypropylene, Beckman Product No: C31597) and centrifuged at 4,500 RPM for 10 minutes. (Beckman Centrifuge model # Avanti JXN-30; with rotor ID J LA-9.1000)

[0072] 5) The solvents were decanted and pellets were washed with 2.0 L of 3:7 (isopropyl ether : hexane) by shaking vigorously in a sealed polypropylene centrifuge canister for about 1 minute, followed by settling and resting for about 10-20 minutes. The pellets were centrifuged again at 4500 RPM for 6 minutes.

[0073] The solvent was decanted, and all pellets from each precipitation batch were combined together in a glass crystallizing dish (150 mm diameter, 75 mm height). The dish was covered loosely with a glass plate, and the combined wet product was stored in a forced air oven at 50°C for about 1 hour. (VWR Forced Air Oven, catalog # 89511-410)

[0074] The partially dried product was moved into a vacuum oven set to 60°C (Across International model # ATO9 Vacuum Oven equipped with a Vacuubrand #MD 1C vacuum pump; rated to 2.0 mbar). The polymer was dried overnight at 60 °C in the vacuum oven to complete the drying process.

[0075] The dried product was transferred with a stainless steel spatula and razor blade to a clean, pre-weighed 500 ml glass jar with screw cap. 199.63 g of a white rubbery solid was obtained as Polymer 1. The 1 H nuclear magnetic resonance (HNMR) spectrum in CDCh was consistent with a polymer material including the monomers used in polymerization. Related results are illustrated in see FIG. 4. The PDMS content was calculated based on the relative proton signal integrations and found to be approximately 10-11% PDMS.

[0076] Synthesis of Polymer- 2

[0077] Polymer 2 was prepared in a manner consistent with Polymer 1 with the following modifications: The amount of polyoxyethylene methyl ether methacrylate used was 290.4 g, the amount of Monomethyacryloxypropyl terminated polydimethylsiloxane used was 33 g, the amount of PEGDA575 used was 6 g, the amount of Al BN used was 0.66 g, and the amount of ethyl acetate used was 1320 ml. The purification and drying procedure was the same as Polymer 1. After drying, 284.01 g of a white rubbery solid was obtained as Polymer 2.

[0078] Synthesis of Polymer-3

[0079] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (9.0 g, 90 wt% monomers) (CAS 26915-72-0, average Mn = 500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (1.0g, 10wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), ethyl acetate (40ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 6 hours and 30 minutes, an additional portion of AIBN (10 mg) was added, and the solution was held at 70 °C for an additional 16 hours. The reaction mixture was allowed to cool to room temperature, and then the solution was poured into an excess of diisopropyl ether, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diisopropyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C overnight. After drying, Polymer 3 was obtained as a white rubbery solid.

[0080] Synthesis of Polymer-4

[0081] The synthesis of Polymer-4 was carried out in a manner consistent with Polymer-3 with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 7.0 g (70 wt% monomers), and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 3.0 g (30 wt% monomers). After drying, Polymer 4 was obtained as a white rubbery solid.

[0082] Synthesis of Polymer-5

[0083] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (8.0 g, 80 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M22, 10000 g / mol, CAS 146632-07-7), ethyl acetate (40 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 6 hours and 30 minutes, an additional portion of AIBN (10 mg) was added, and the solution was held at 70 °C for an additional 16 hours. The reaction mixture was allowed to cool to room temperature, and then the solution was poured into an excess of diisopropyl ether, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diisopropyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C overnight. After drying, Polymer 5 was obtained as a white, viscous thixotropic liquid.

[0084] Synthesis of Polymer-6

[0085] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (6.0 g, 60 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 2 0wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), tetrahydrofurfuryl acrylate (2.0 g, 20 wt% monomers) (Sigma Aldrich Millipore, St. Louis, Mo., catalog number 408271 , CAS 2399-48-6), ethyl acetate (40 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 30 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 5 hours, an additional portion of AIBN (10 mg) was added, and the solution was held at 70 °C for an additional 19 hours. The reaction mixture was allowed to cool to room temperature, and then the solvent was evaporated under reduced pressure. The residue was washed sequentially with hexane, methanol, and water. The washing solvent was decanted, and the washed residues were dried in a vacuum oven at 60 °C for overnight. After drying, Polymer 6 was obtained as a white rubbery solid.

[0086] Synthesis of Polymer-7

[0087] Polymer 7 was prepared in a manner consistent with Polymer 6 with the following differences: Polyoxyethylene methyl ether methacrylate was replaced with polyethylene glycol methyl ether acrylate (product number 454990, CAS 32171-39-4, average Mn 480 g / mol, Sigma Aldrich Millipore, St. Louis, Mo), and tetrahydrofurfuryl acrylate was replaced with tetrahydrofurfuryl methacrylate (Sigma Aldrich Millipore, St. Louis, Mo., product number 409456, CAS 2455-24-5). After drying, Polymer 7 was obtained as a white rubbery solid.

[0088] Synthesis of Polymer-8

[0089] Polymer 8 was prepared in a manner consistent with Polymer 6 with the following difference: Polyoxyethylene methyl ether methacrylate was replaced with polyethylene glycol methyl ether acrylate (product number 454990, CAS 32171-39-4, average Mn 480 g / mol, Sigma Aldrich Millipore, St. Louis, Mo). After drying, Polymer 8 was obtained as a white rubbery solid.

[0090] Synthesis of Polymer-9

[0091] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (8.0 g, 80 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), ethyl acetate (25 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 16 hours the reaction mixture was allowed to cool to room temperature, the products were concentrated by partial evaporation of the solvent, and then the residue was poured into an excess of diisopropyl ether, producing a precipitate. The solvent was decanted, and then the precipitates were washed with diisopropyl ether. The washing solvent was decanted, and then the precipitates were dried in a vacuum oven at 60 ° for overnight. Polymer 9 was obtained as a white rubbery solid.

[0092] Synthesis of Polymer-10

[0093] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (8.0 g, 80 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), ethyl acetate (40 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 19 hours, another portion of AIBN (10 mg) was added and the mixture was maintained at an internal temperature of 70 °C for another 22 hours. After cooling to room temperature, the product was concentrated by evaporation of the solvent under reduced pressure, and then the residue was poured into hexane to produce a precipitate. The solvent was decanted, and the precipitate was further washed with diisopropyl ether. The washing solvent was decanted, and the precipitate was dried in a vacuum oven at 60 °C overnight. Polymer 10 was obtained as a rubbery white solid.

[0094] Synthesis of Polymer-11

[0095] Polymer 11 was prepared in the same manner as Polymer 10 with the following difference: polyoxyethylene methyl ether methacrylate (CAS 26915-72-0, average Mn = 500 g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.) was replaced with polyoxyethylene methyl ether methacrylate having average Mn = 950 (product number 447951 , CAS 26915-72-0, average Mn = 950g / mol, Sigma Aldrich Millipore, St. Louis, Mo.). Polymer 11 was obtained as a white waxy solid.

[0096] Synthesis of Polymer-12

[0097] A 100 ml 2-neck round bottom flask was oven dried, placed in an aluminum heating block on a hot plate stirrer and charged with polyoxyethylene methyl ether methacrylate (8.0 g, 80 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (1.5 g, 15 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), a magnetic stirrer, acrylamide (0.5 g, 5 wt% monomers) (product number 01700, CAS 79-06-1 , Sigma Aldrich Millipore, St. Louis, Mo.), azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo), and ethyl acetate (40 ml). The two necks of the flask were capped with rubber septa. The mixture was stirred until a homogeneous solution was obtained, and then argon gas was sparged into the solution through a stainless steel needle for 30 minutes. The needle was moved to the headspace of the flask and the gas outlet needle was removed. The heating block was heated to 75 °C for 18 hours. The mixture was allowed to cool to room temperature, and then the product was concentrated by partial removal of the solvent under reduced pressure on a rotary evaporator. The resulting viscous solution was poured into an excess of hexane (about 400 ml), and a precipitate was formed. The solvents were decanted, and then the precipitates were washed by two more cycles of washing with hexane and decanting of the washing solvent. The precipitates were dried in a vacuum oven at 60 °C overnight, and Polymer 12 was obtained as 6.1 grams of a firm, white, rubbery solid.

[0098] Synthesis of Polymer-13

[0099] A 100 ml 2-neck round bottom flask was oven dried, placed in an aluminum heating block on a hot plate stirrer and charged with polyoxyethylene methyl ether methacrylate (7.0 g, 70 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), a magnetic stirrer, acrylamide (1.0 g, 10 wt% monomers) (product number 01700, CAS 79-06-1 , Sigma Aldrich Millipore, St. Louis, Mo.), azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo), and ethyl acetate (40 ml). The two necks of the flask were capped with rubber septa. The mixture was stirred until a homogeneous solution was obtained, and then argon gas was sparged into the solution through a stainless steel needle for 30 minutes. The needle was moved to the headspace of the flask and the gas outlet needle was removed. The heating block was heated to 75 °C for 18 hours. T o the resulting thixotropic viscous solution was added N,N-dimethylformamide (40 ml) while keeping the heater at 75 °C with stirring to reduce the viscosity. The resulting hazy, viscous solution was poured into about 600 ml of a mixture of 15 vol% isopropanol in hexane. A precipitate was formed. The precipitate was separated from the solvent by means of centrifugation (Beckman Centrifuge model # Avanti JXN-30; with rotor ID JA-10) at 5,000 RPM for 6 minutes. After decanting the solvents, the precipitate was further washed with another 600 ml portion of 15 vol% isopropanol in hexane, and then it was centrifuged again in the same conditions. After decanting the solvents, the precipitates were partially dried under a dry nitrogen gas stream, and then transferred to a glass jar. The product was dried in a vacuum oven at 60 °C overnight, and Polymer 13 was obtained as 7.0 grams of a firm, white, rubbery solid.

[0100] Synthesis of Polymer-14

[0101] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (9.1 g, 91 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (0.7 g, 7 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), polyethylene glycol diacrylate (0.2 g, 2 wt% monomers) (PEGDA575, Sigma-Aldrich, 437441 , CAS 26570-48-9, average Mn = 575 g / mol), ethyl acetate (40 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 16 hours, an additional portion of AIBN (10 mg) was added, and the solution was held at 70 °C for an additional 8 hours. The reaction mixture was allowed to cool to room temperature, and then was poured into an excess of hexane, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diethyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C overnight. Polymer 14 was obtained as a rubbery white solid. Synthesis of Polymer-15

[0102] Polymer 15 was prepared in the same manner as polymer 14, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 9.3 g (93 wt% monomers), and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 0.5 g (5 wt%) monomers. Polymer 15 was obtained as a white rubbery solid.

[0103] Synthesis of Polymer-16

[0104] Polymer 16 was prepared in the same manner as polymer 14, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 9.5 g (95 wt% monomers), and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 0.3 g (3 wt%) monomers. Polymer 16 was obtained as a white rubbery solid.

[0105] Synthesis of Polymer-17

[0106] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (9.3 g, 93 wt% monomers) (CAS 26915-72-0, average Mn = 500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (0.7 g, 7 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), ethyl acetate (40 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78- 67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 16 hours of heating, the reaction mixture was allowed to cool to room temperature, and then was poured into an excess of hexane, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diethyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C overnight. Polymer 17 was obtained as a rubbery white solid.

[0107] Synthesis of Polymer-18

[0108] Polymer 18 was prepared in the same manner as polymer 17, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 9.5 g (95 wt% monomers) and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 0.5 g (5 wt% monomers). Polymer 18 was obtained as a white thixotropic liquid.

[0109] Synthesis of Polymer-19

[0110] Polymer 19 was prepared in the same manner as polymer 17, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 9.7 g (97 wt% monomers) and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 0.3 g (3 wt% monomers). Polymer 19 was obtained as a white soft rubbery solid.

[0111] Synthesis of Polymer-20

[0112] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (9.3 g, 93 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (0.7 g, 7 wt% monomers) (Gelest, Inc., MCR-M22, 10000 g / mol, CAS 146632-07-7), ethyl acetate (40ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 18 hours of heating, another portion of AIBN (10 mg) was added, and the heating continued for another 23 hours. The reaction mixture was allowed to cool to room temperature, and then was poured into an excess of hexane, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diethyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C for overnight. Polymer 20 was obtained as a rubbery white solid.

[0113] Synthesis of Polymer-21

[0114] Polymer 21 was prepared in the same manner as polymer 20, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 9.5 g (95 wt% monomers) and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 0.5 g (5 wt% monomers). Polymer 21 was obtained as a white rubbery solid. Synthesis of Polymer-22

[0115] Polymer 22 was prepared in the same manner as polymer 20, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 9.7 g (97 wt% monomers) and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 0.3 g (3 wt% monomers). Polymer 22 was obtained as a white thixotropic liquid.

[0116] Synthesis of Polymer-23

[0117] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate (5.0 g, 50 wt% monomers) (CAS 26915-72-0, average Mn = 500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (5.0 g, 50 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), ethyl acetate (50 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 19 hours of heating, another portion of AIBN (10 mg) was added, and the heating continued for another 19 hours. The reaction mixture was allowed to cool to room temperature, the solvent was removed under reduced pressure, and then the concentrated product was poured into an excess of diisopropyl ether, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diethyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C overnight. Polymer 23 was obtained as a white thixotropic liquid.

[0118] Synthesis of Polymer-24

[0119] Polymer 24 was prepared in the same manner as Polymer 23, with the following differences: the monomethyacryloxypropyl terminated polydimethylsiloxane used was MCR-M22 (Gelest, Inc.) having molecular weight 10,000 g / mol, and the amount of ethyl acetate used was 60 ml. Polymer 24 was obtained as a white thixotropic liquid.

[0120] Synthesis of Polymer-25

[0121] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyoxyethylene methyl ether methacrylate 7.0 g, 70 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), tetrahydrofurfuryl methacrylate (1.0 g, 10 wt% monomers) (Sigma Aldrich Millipore, St. Louis, Mo., product number 409456, CAS 2455-24-5), ethyl acetate (40 ml), and Azobisisobutyronitrile (50 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 30 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 14 hours of heating, the reaction mixture was allowed to cool to room temperature and the product was concentrated by partially removing the solvent under reduced pressure. The concentrated product was poured into hexane, and a precipitate was formed. The solvent was decanted, and then the precipitate was dried in a vacuum oven at 60 °C overnight. Polymer 25 was obtained as a white rubbery solid.

[0122] Synthesis of Polymer-26

[0123] Polymer 26 was prepared in a manner consistent with Polymer 4, with the following differences: polyoxyethylene methyl ether methacrylate was replaced with polyethylene glycol methyl ether acrylate (product number 454990, CAS 32171-39-4, average Mn 480 g / mol, Sigma Aldrich Millipore, St. Louis, Mo), and the additional portion of AIBN (10 mg) was added after 15 hours of heating. After the second portion of AIBN was added, the reaction was held at a temperature setting of 85 °C for 15 hours. After being allowed to cool to room temperature, the solvent was removed under reduced pressure, and the concentrated product was poured into a 7:3 mixture of hexane and isopropanol to produce a precipitate. The solvent was decanted and the product was dried in a vacuum oven at 60 °C overnight. Polymer 26 was obtained as a waxy white solid.

[0124] Synthesis of Polymer-27

[0125] Polymer 27 was prepared in a manner consistent with Polymer 4, with the following differences: polyoxyethylene methyl ether methacrylate was replaced with polyethylene glycol methyl ether acrylate (product number 454990, CAS 32171-39-4, average Mn 480 g / mol, Sigma Aldrich Millipore, St. Louis, Mo), and monomethyacryloxypropyl terminated polydimethylsiloxane (Gelest, Inc., MCR-M11 , 1000 g / mol, CAS 146632-07-7) was used in place of MCR-M17. The second portion of AIBN (10 mg) was added after 15 hours of heating. After cooling to room temperature, the solvent was removed under reduced pressure and the concentrated product was poured into hexane to produce a precipitate. The solvents were decanted, and the precipitate was further washed with diisopropyl ether. After decanting the washing solvent, the precipitate was dried in a vacuum oven at 60 °C overnight. Polymer 27 was obtained as a highly viscous liquid.

[0126] Synthesis of Polymer-28

[0127] A 100 ml 2-neck round bottom flask equipped with an air-cooled condenser was charged with a magnetic stirrer, polyethylene glycol methyl ether acrylate (7.8 g, 78 wt% monomers) (product number 454990, CAS 32171-39-4, average Mn 480 g / mol, Sigma Aldrich Millipore, St. Louis, Mo), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M11 , 1000 g / mol, CAS 146632-07-7), polyethylene glycol diacrylate (0.2 g, 2 wt% monomers) (PEGDA575, Sigma-Aldrich, 437441 , CAS 26570-48-9, average Mn=575 g / mol), ethyl acetate (40 ml), and Azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo). The mixture was heated to 40 °C with stirring while nitrogen gas was sparged into the liquid through a needle for 30 minutes. Then, the nitrogen needle was moved out of the solution, and the temperature setting was increased to 85 °C, which resulted in a solution temperature of 70 °C. After 18 hours, an additional portion of AIBN (10 mg) was added, and the solution was held at 70 °C for an additional 24 hours. The reaction mixture was allowed to cool to room temperature, and then the solvent was removed by evaporation under reduced pressure. The concentrated residue was poured into an excess of hexane, producing a precipitate. The liquid was decanted, and the precipitates were further washed with diisopropyl ether. The washing solvent was decanted, and the washed precipitates were dried in a vacuum oven at 60 °C overnight. After drying, Polymer 28 was obtained as a viscous, thixotropic liquid.

[0128] Synthesis of Polymer-29

[0129] Polymer 29 was prepared in the same manner as Polymer 28, with the following differences: the amount of polyethylene glycol methyl ether acrylate used was 7.5 g (75 wt% monomers) and the amount of polyethylene glycol diacrylate used was 0.5 g (5 wt% monomers). Polymer 29 was obtained as a thixotropic liquid.

[0130] Synthesis of Polymer-30

[0131] A 100 ml 2-neck round bottom flask was oven dried, placed in an aluminum heating block on a hot plate stirrer and charged with polyoxyethylene methyl ether methacrylate (8.0 g, 80 wt% monomers) (CAS 26915-72-0, average Mn=500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (1.0 g, 10 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), a magnetic stirrer, 1-vinylimidazole (1.0 g, 10 wt% monomers) (product number 235466, CAS 1072-63-5, Sigma Aldrich Millipore, St. Louis, Mo.), azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo), and ethyl acetate (40 ml). The two necks of the flask were capped with rubber septa. The mixture was stirred until a homogeneous solution was obtained, and then argon gas was sparged into the solution through a stainless steel needle for 30 minutes. The needle was moved to the headspace of the flask and the gas outlet needle was removed. The heating block was heated to 75 °C for 22 hours. Upon cooling to room temperature, the reaction mixture was poured into 600 ml of hexane and a precipitate was formed. The precipitate was separated from the solvent by means of centrifugation (Beckman Centrifuge model # Avanti JXN-30; with rotor ID JA-10) at 5,000 RPM for 6 minutes. After decanting the solvents, the precipitate was further washed with 600 ml of diethyl ether, and then it was centrifuged again in the same conditions. After decanting the solvents, the precipitates were transferred to a glass jar. The product was dried in a vacuum oven at 60 °C overnight, and Polymer 30 was obtained as 8.6 grams of an off- white translucent soft rubbery solid.

[0132] Synthesis of Polymer-31

[0133] Polymer 31 was prepared in the same manner as Polymer 30, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 7.0 g, the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 2.0 g, and the heating time for polymerization was 24 hours. Polymer 31 was obtained as 4.85 grams of an off-white translucent soft rubbery solid.

[0134] Synthesis of Polymer-32

[0135] Polymer 32 was prepared in the same manner as Polymer 30, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 7.0 g, the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 1.5 g, the amount of 1-vinylimidazole used was 1.5 g, and the heating time for polymerization was 18 hours. Polymer 32 was obtained as 8.5 grams of an off-white translucent soft rubbery solid.

[0136] Synthesis of Polymer-33

[0137] A 100 ml 2-neck round bottom flask was oven dried, placed in an aluminum heating block on a hot plate stirrer and charged with polyoxyethylene methyl ether methacrylate (8.0 g, 80 wt% monomers) (CAS 26915-72-0, average Mn = 500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (1.5 g, 15 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), a magnetic stirrer, 1-vinylimidazole (0.5 g, 5 wt% monomers) (product number 235466, CAS 1072-63-5, Sigma Aldrich Millipore, St. Louis, Mo.), azobisisobutyronitrile (10mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo), and ethyl acetate (40 ml). The two necks of the flask were capped with rubber septa. The mixture was stirred until a homogeneous solution was obtained, and then argon gas was sparged into the solution through a stainless steel needle for 43 minutes. The needle was moved to the headspace of the flask and the gas outlet needle was removed. The heating block was heated to 75 °C for 24 hours. Upon cooling to room temperature, the reaction mixture was poured into 600 ml of hexane and a precipitate was formed. The precipitate was separated from the solvent by means of centrifugation (Beckman Centrifuge model # Avanti JXN-30; with rotor ID JA-10) at 5,000 RPM for 6 minutes. After decanting the solvents, the precipitate was re-dissolved in 20 ml of ethyl acetate. The ethyl acetate solution was poured into 600 ml of hexane, forming a precipitate. The solid was separated from the solvent by means of centrifugation (Beckman Centrifuge model # Avanti JXN-30; with rotor ID JA-10) at 5,000 RPM for 6 minutes. After decanting the solvents, the precipitate was transferred to a pre-weighed glass jar and dried in a vacuum oven (Across International model # ATO9 Vacuum Oven equipped with a Vacuubrand #MD 1C vacuum pump; rated to 2.0 mbar) at 60°C overnight. Polymer 33 was obtained as 6.36 g of a translucent rubbery solid.

[0138] Synthesis of Polymer-34

[0139] Polymer 34 was prepared in the same manner as Polymer 33, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 7.5 g, and the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 2.0 g. Polymer 34 was obtained as 1.29 g of a translucent rubbery solid.

[0140] Synthesis of Polymer-35

[0141] Polymer 35 was prepared in the same manner as Polymer 33, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 7.5 g, the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 1.7 g, and the amount of 1-vinylimidazole used was 0.8 g. Polymer 35 was obtained as 3.72 g of a translucent rubbery solid. Synthesis of Polymer-36

[0142] A 100 ml 2-neck round bottom flask was oven dried, placed in an aluminum heating block on a hot plate stirrer and charged with polyoxyethylene methyl ether methacrylate (6.0 g, 60 wt% monomers) (CAS 26915-72-0, average Mn = 500g / mol, product number 447943, Sigma Aldrich Millipore, St. Louis, Mo.), monomethyacryloxypropyl terminated polydimethylsiloxane (2.0 g, 20 wt% monomers) (Gelest, Inc., MCR-M17, 5000 g / mol, CAS 146632-07-7), a magnetic stirrer, tetrahydrofurfuryl methacrylate (2.0 g, 20 wt% monomers) (product number 409456, CAS 2455-24-5, Sigma Aldrich Millipore, St. Louis, Mo.), azobisisobutyronitrile (10 mg) (AIBN, CAS 78-67-1 , 441090, Sigma Aldrich Millipore, St. Louis, Mo), and ethyl acetate (40 ml). The two necks of the flask were capped with rubber septa. Argon gas was sparged into the solution through a stainless steel needle for 30 minutes. The needle was moved to the headspace of the flask and the gas outlet needle was removed. The heating block was heated to 75 °C for 24 hours. Upon cooling to room temperature, the reaction mixture was poured into 600 ml of hexane and a precipitate was formed. The precipitate was separated from the solvent by means of centrifugation (Beckman Centrifuge model # Avanti JXN-30; with rotor ID JA-10) at 5,000 RPM for 6 minutes. After decanting the solvents, the precipitate was further washed with 600 ml of hexane, and then it was centrifuged again in the same conditions. After decanting the solvents, the precipitates were transferred to a glass jar. The product was dried in a vacuum oven at 60 °C for about 17 hours, and Polymer 36 was obtained as 5.28 grams of a tacky white solid.

[0143] Synthesis of Polymer-37

[0144] Polymer 37 was prepared in the same manner as Polymer 36, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 7.0 g, and the amount of tetrahydrofurfuryl methacrylate used was 1.0 g. Polymer 37 was obtained as 6.01 g of a tacky white solid.

[0145] Synthesis of Polymer-38

[0146] Polymer 38 was prepared in the same manner as Polymer 36, with the following differences: the amount of polyoxyethylene methyl ether methacrylate used was 8.0 g, the amount of monomethyacryloxypropyl terminated polydimethylsiloxane used was 1.5 g, and the amount of tetrahydrofurfuryl methacrylate used was 0.5 g. Polymer 38 was obtained as 7.79 g of a tacky white solid. Preparation of Support Layer-1

[0147] Material

[0148] A PTMSP polymer solution was prepared by dissolving 3 grams of poly(trimethylsilyl)propyne PTMSP (Gelest Inc.) in 150 grams of cyclohexane (Sigma Aldrich), and stirring it overnight.

[0149] The PTMSP cyclohexane solution was coated on a polysulfone porous substrate (Hydranautics, SWC product line) on a vacuum coating stage using an applicator with a blade gap of 3 mm (1 mm = 25.4 microns) or 4 mm.

[0150] The coating was dried in air at room temperature for 5 minutes to form the Support Layer- 1.

[0151] Preparation of Selective Layer / Membrane-1, Examples 1-A, 1-B, 1-C

[0152] 0.3 g of Polymer 1 and 15 g of ethanol (KOPTEC, 190 proof pure ethanol) were combined in a glass vial and stirred using a magnetic stirrer at 500 rpm overnight to prepare a casting solution.

[0153] The solution of Polymer 1 in ethanol was coated on Support Layer 1 using an applicator, and the membrane was dried at 70°C for 10 minutes to form Examples 1-A, 1-B, and 1- C. For Example 1-A, the applicator blade height was 2 mm. For Example 1-B, the applicator blade height was 1 mm. For Example 1-C, the casting solution was further diluted to 1 wt% polymers, and the applicator blade height was 1 mm.

[0154] For the purpose of organizing data for multiple membranes, a value of selective layer thickness was calculated by the formula:

[0155] L = p * h * 25.4 * f

[0156] In this formula, L is selective layer dry thickness in microns, p is casting solution concentration (for a 2 wt% solution, p is 0.02), h is the gap or height of the applicator in mm, and f = 0.7, where f is a factor obtained from cross-section microscope analysis of a few exemplary membranes.

[0157] In the preparation of other examples, the procedure was similar to that of preparation of Examples 1-A, 1-B, and 1-C, but the drying procedure was varied. In some examples, the membranes were dried at room temperature, e.g. they were allowed to stand in ambient air for 1-4 hours until the casting solvent evaporated. In other examples, the membranes were dried by storing in a vacuum chamber for about 2 hours to cause evaporation of the casting solvent. In examples 30-35, the polymers were dissolved to 1 wt% in pure isopropanol to form their respective casting solutions. Gas Separation Measurement Procedure:

[0158] The Gas Separation Membranes of Example 1 were cut to size and installed into a permeance cell (CF016A-FO, by Sterlitech) between the feed side and sweep side. The testing area of the sample was 20.6 cm2. A schematic illustration of an apparatus for testing gas selectivity / separation measurement is provided in Fig. 4. In this apparatus, the feed side was supplied with 100 ml / min of CO2 / N2 mixed gas in a 10 / 90 ratio by setting the mass flow controllers to 10 ml / min for CO2 and 90ml / min for N2. The sweep side of the cell was fed with helium at 30ml / min. The gasses were allowed to flow for 10 minutes and then the sweep gas was injected into a Shimadzu GC-2010 to measure the amount of CO2 and N2 that passed through the membrane.

[0159] F1-F3 represent mass flow controllers which may be Masterflex® Mass Flowmeter Controllers for Gas, although other variations are possible. Results from the gas separation measurements are provided in the following table.

[0160]

[0161] Comparative Example C1 : Pebax Membrane

[0162] A solvent mixture was prepared by mixing 70 weight % ethanol and 30 weight % water. Pebax MH 1657 (hereafter, “Pebax”, Arkema) was added to the solvent mixture to produce a 2 weight% solution of Pebax. The mixture was stirred with heating to 80 °C for 2 hours and a homogeneous solution was obtained. The solution was cooled to room temperature and filtered through a syringe filter with a 1 micron pore size. The solution was cast on Support Layer 1 by using an applicator blade. The applicator blade height for examples C1-A, C1-B, and C1-C was 1 mm, 2 mm, and 4 mm, respectively. The casted film was then dried in an oven at 85 °C for 30 minutes.

[0163] PEBAX film

[0164] _ CO2 Select. N2

[0165] Sample ID Thickness -

[0166] - GPU CO2 / N2 GPU

[0167] C1-A 0.36 urn 166 38 4.3

[0168] C1-B 0.71 urn 111 42 1.9

[0169] C1-C 1.42 urn 78 47 2.4

[0170] Example Procedure of Forming a Protective Layer

[0171] A selective layer was formed according to the procedure for preparation of a selective layer, and a portion of the membrane was cut out and evaluated using the Gas Separation Measurement Procedure. A silicone emulsion casting solution was prepared by combining 2.5 g POLON-56-T (Shin Etsu) and 17.5 g of purified water (MilliQ) in a 40 ml vial. The mixture was stirred with a magnetic stirrer for at least 1 hour.

[0172] The emulsion casting solution was coated on the selective layer by means of an applicator with a blade clearance of 1 mm, followed by drying at 125 °C in an oven for 15 minutes to form a composite gas separation membrane including a protective layer. A portion of the composite gas separation membrane was cut out and evaluated using the Gas Separation Measurement Procedure to assess any differences in gas permeance and selectivity before and after depositing the protective layer.

[0173] The procedure for forming a protective layer was applied to polymers 2, 3, 4, 5, and polymers 14-24. The percentage change in selectivity for CO2 over N2 as measured by the Gas Separation Measurement Procedure after the emulsion coating as compared to the selectivity of the membrane without the protective layer is shown in Fig. 5. The data demonstrates that polymers including PDMS side-chains in quantities greater than about 3 wt% are generally able to maintain at least 80% of their gas separation selectivity after coating with a silicone protective layer.

[0174] As used herein, unless otherwise specified the use of the ordinal adjectives “first” and “second,” to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

[0175] Use of the term “may” or “may be” should be construed as shorthand for “is” or “is not” or, alternatively, “does” or “does not” or “will” or “will not,” etc. For example, the statement “a first polymeric side-chain may include a polysiloxane” should be interpreted as, for example, “In some embodiments, a first polymeric side-chain includes a polysiloxane,” or “In some embodiments, a first polymeric side-chain does not include a polysiloxane.”

[0176] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties, such as, molecular weight, reaction conditions, and so forth used in the specification and embodiments are to be understood as being modified in all instances by the term “about.” The term “about” as used herein, can include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” also discloses the range defined by the absolute values of the two endpoints. The term “about” may refer to plus or minus 10% of the indicated number.

[0177] Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached embodiments are approximations that may vary depending upon the desired properties sought to be obtained. At the very least, and not as an attempt to limit the application of the doctrine of equivalents. To the scope of the embodiments, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0178] For the processes and / or methods disclosed, the functions performed in the processes and methods may be implemented in differing order, as may be indicated by context. Furthermore, the outlined steps and operations are only provided as examples and some of the steps and operations may be optional, combined into fewer steps and operations, or expanded into additional steps and operations.

[0179] This disclosure may sometimes illustrate different components contained within, or connected with, different other components. Such depicted architectures are merely examples, and many other architectures may be implemented which achieve the same or similar functionality.

[0180] The terms used in this disclosure and in the appended embodiments, (e.g., bodies of the appended embodiments) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including, but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes, but not limited to,” etc.). In addition, if a specific number of elements is introduced, this may be interpreted to mean at least the recited number, as may be indicated by context (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations of two or more recitations). As used in this disclosure, any disjunctive word and / or phrase presenting two or more alternative terms should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phase “A or B”: will be understood to include the possibilities of “A” or “B” or “A and B.”

[0181] The terms and words used are not limited to the bibliographical meanings but are merely used to enable a clear and consistent understanding of the disclosure. The terms “a,” “an,” “the” and similar referents used in the context of describing the present disclosure (especially in the context of the following embodiments) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples, or representative language (e.g., “such as”) provided herein is intended merely to better illuminate the present disclosure and does not pose a limitation on the scope of any embodiments. No language in the specification should be construed as indicating any non-embodied element essential to the practice of the present disclosure.

[0182] Groupings of alternative elements or embodiments disclosed herein are not to be construed as limitations. Each group member may be referred to and embodied individually or in any combination with other members of the group or other elements found herein. It is anticipated that one or more members of a group may be included in, or deleted from, a group for reasons of convenience and / or patentability. When any such inclusion or deletion occurs, the specification is deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended embodiments.

[0183] Certain embodiments are described herein, including the best mode known to the inventors for carrying out the present disclosure. Of course, variations on these described embodiments, will become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor expects skilled artisans to employ such variations as appropriate, and the inventors intend for the present disclosure to be practiced otherwise than specifically described herein. Accordingly, the embodiments include all modifications and equivalents of the subject matter recited in the embodiments as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is contemplated unless otherwise indicated herein or otherwise clearly contradicted by context. In closing, it is to be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments. Other modifications that may be employed are within the scope of the embodiments. Thus, by way of example, but not of limitation, alternative embodiments may be utilized in accordance with the teachings herein. Accordingly, the embodiments are not limited to the embodiments precisely as shown and described.

[0184] By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those skilled in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0185] Aspects of the present disclosure may be embodied in other forms without departing from its spirit or essential characteristics. The described aspects are to be considered in all respects illustrative and not restrictive. The embodied subject matter is indicated by the appended embodiments rather than by the foregoing description. All changes, which come within the meaning and range of equivalency of the embodiments, are to be embraced within their scope.

Claims

CLAIMSWhat is claimed is:1 . A graft copolymer, comprising: a backbone of repeating units; and at least a first polymeric side-chain, wherein the first polymeric side-chain includes a polysiloxane; at least a second polymeric side-chain, wherein the second polymeric side-chain includes a polyether; and wherein the first polymeric side-chain accounts for about 3 wt% to about 50 wt% of the graft copolymer and the second polymeric side-chain accounts for about 97% wt% to about 50 wt% of the graft copolymer.

2. The graft copolymer of claim 1 , wherein the backbone includes a polyacrylate.

3. The graft copolymer of claim 1 , wherein the first polymeric side chain includes an alkyl siloxane.

4. The graft copolymer of claim 1 , wherein the first polymeric side chain includes a polydimethyl siloxane.

5. The graft copolymer of claim 1 , wherein the second polymeric side chain includes a polyethylene glycol.

6. The graft copolymer of claim 1, wherein the graft copolymer is according to the following formula (1):(Formula I), wherein each of m and n2 is an integer greater than or equal to 1.

7. The graft copolymer of any one of claims 1-6, further including a third polymeric side-chain.

8. The graft copolymer of claim 7, wherein the third polymeric side chain includes at least one of acrylamide, a vinylimidazole, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, 5-oxotetrahydrofuran-3-yl methacrylate, glycidyl methacrylate, and polyethylene glycol diacrylate.

9. The graft copolymer of claim 8, wherein the graft copolymer is according to the following formula (2) :(Formula 2), wherein the first side-chain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer;wherein the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer; and wherein the third side-chain (z) accounts for about 0.1 wt% to about 5 wt% of the graft copolymer.

10. The graft copolymer of claim 8, wherein the graft copolymer is according to the following formula (3):(Formula 3) wherein each of m and n2 is an integer greater than or equal to 1 ; wherein the first side-chain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer; wherein the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer; and wherein the third side-chain (z) accounts for about 0.1 wt% to about 38 wt% of the graft copolymer.

11. The graft copolymer of claim 8, wherein the graft copolymer is according to the following formula (4):(Formula 4)wherein each of ni and n2 is an integer greater than or equal to 1 ; wherein the first side-chain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer; wherein the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer; and wherein the third side-chain (z) accounts for about 0.1 wt% to about 38 wt% of the graft copolymer.

12. The graft copolymer of claim 8, wherein the graft copolymer is according to the following formula (5):(Formula 5) wherein each of m and n2 is an integer greater than or equal to 1 ; wherein the first side-chain (x) accounts for about 2 wt% to about 40 wt% of the graft copolymer; wherein the second side-chain (y) accounts for about 60 wt% to about 98 wt% of the graft copolymer; and wherein the third side-chain (z) accounts for about 0.1 wt% to about 38 wt% of the graft copolymer.

13. The graft copolymer of claim 1 , wherein the polyether includes at least one of polyoxyethylene methyl ether methacrylate monomer (POEM) and PEG acrylate (PEGMEA).

14. A casting solution comprising a graft copolymer of any one claims 1-13.

15. The casting solution of claim 14, wherein the casting solution includes polyethylene glycol diacrylate.

16. A membrane comprising a graft copolymer of any one of claims 1-13.

17. A gas separation membrane, comprising a graft copolymer of any one of embodiments 1-13 and exhibits selectivity of CO2 over N2.

18. The gas separation membrane of claim 17, wherein the membrane includes: a porous substrate; a first layer including a silicon containing polymer; and a gas selective layer including a graft copolymer according to any one of claims 1-14.

19. The gas separation membrane of claim 18 further comprising a polysiloxane protective layer disposed upon the gas selective layer.

20. A method for making a gas membrane, comprising: providing a graft copolymer including: a backbone of repeating units; at least a first polymeric side-chain, wherein the first polymeric side-chain includes a polysiloxane; at least a second polymeric side-chain, wherein the second polymeric sidechain includes a polyether; wherein the first polymeric side-chain accounts for about 3 wt% to about 40 wt% of the sidechain polymers and the second polymeric side-chain accounts for about 60% wt% to about 97 wt% of the side-chain polymers; creating a casting solution including the graft copolymer; casting the casting solution onto a substrate to form a film; and annealing the film to form a gas membrane.

21. The method of claim 20, wherein the graft copolymer further comprises a third polymer side-chain, and the third side-chain accounts for less than about 38 wt% of the graft copolymer.

22. The method of claim 21 , wherein the third polymer side-chain includes at least one of polyethylene glycol diacrylate, vinylimidazole, tetrahydrofurfuryl methacrylate, and acrylamide.

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