CLAIM OF PRIORITY

[0001] This application claims the benefit of priority of U.S. Patent Application Serial No. 61/579,146, entitled "SILICONE-BASED IONIC LIQUIDS AND

APPLICATIONS THEREOF," filed on December 22, 201 1 , which application is incorporated by reference herein in its entirety.

[0002] Ionic liquids are salts containing poorly coordinated ions, which can render the melting point of the salts equal to or close to room temperature. Many ionic liquids have even been developed in recent years for applications such as solvents, lubricants, anti-microbial agents, homogeneous and heterogeneous catalysis, treatment of high-level nuclear waste, and metal ion removal.

SUMMARY OF THE INVENTION

[0003] Embodiments of the present invention provide silicone-based ionic liquids and methods of making the same, curable compositions that include the same, materials such as membranes made therefrom, and methods of using those materials. Various embodiments of the present invention provide a curable composition that includes a polysiloxane having an average of at least about one quaternary phosphonium group or quaternary ammonium group per molecule, a cured product of the curable composition, a supported or unsupported membrane including the cured product, and a method of separating gas components in a feed gas mixture using the membrane.

[0004] Various embodiments of the present invention provide a curable composition. The curable composition includes Component (A), an organic compound having at least one free-radical polymerizable group per molecule. The curable composition also includes Component (B), a mercapto-functional organic compound having an average of at least about three mercapto groups per molecule. The curable composition also includes Component (C), a polysiloxane having an average of at least about one quaternary phosphonium group or quaternary ammonium group per molecule, wherein the polysiloxane has an average of at least about five Si atoms per molecule. Additionally, the curable composition includes a catalytic amount of a free-radical initiator.

[0005] Various embodiments of the present invention provide a method of separating gas components in a feed gas mixture. The method includes contacting a first side of a membrane with a feed gas mixture. The membrane includes a cured product of a curable composition. The feed gas mixture includes at least a first gas component and a second gas component. The contacting produces a permeate gas mixture on a second side of the membrane. The contacting also produced a retentate gas mixture on the first side of the membrane. The permeate gas mixture is enriched in the first gas component. The retentate gas mixture is depleted in the first gas component. The curable composition includes Component (A), an organic compound having at least one free-radical polymerizable group per molecule. The curable composition also includes Component (B), a mercapto-functional organic compound having an average of at least about three mercapto groups per molecule. The curable composition also includes Component (C), a polysiloxane having an average of at least about one quaternary phosphonium group or quaternary ammonium group per molecule, wherein the polysiloxane has an average of at least about five Si atoms per molecule. Additionally, the curable composition includes a catalytic amount of a free-radical initiator.

[0006] Various embodiments of the present invention have certain advantages over other ionic liquids or products such as membranes made therefrom, at least some of which are unexpected. In some examples, the ionic liquids of the present invention are neither known nor suggested in the art. In some examples, the present invention advantageously combines the high gas permeability of silicones with the exceptional selectivity of ionic liquids to form new materials that can have a variety of beneficial properties. Some embodiments of the membrane of the present invention have higher permeability or selectivity for particular components in a gas mixture than other membranes. In some examples, membranes of the present invention exhibit higher CO2/N2 or CO2/CH4 selectivity, while retaining high permeability, as compared to other membranes. In various embodiments, the silicone-based ionic liquids, or materials such as membranes made therefrom, can be made more efficiently than materials or membranes made using other methods. In various embodiments, the membranes or materials of the present invention made from silicone-based ionic liquids can have properties that are more difficult to achieve in membranes or materials made by other methods.

[0007] Some procedures of making ionic liquids suffer from problems including pre-made salt-groups being immiscible in any solvent conditions with polysiloxanes. The difficulty and limitations of other procedures can discourage one of skill in the art from pursuing membrane applications of silicon-based ionic liquids. In various embodiments, the method of making silicone-based ionic liquids solves these limitations and problems, for example via a different synthetic route. In some examples, the method allows access silicone-based ionic liquids that are neither known nor suggested in the art. In various embodiments, the method of making ionic liquids is superior to other methods, including because it has fewer and simpler synthetic steps, uses cheaper starting materials than other methods, allows access to a greater number of ionic liquids such as by giving greater control over the linking group between the salt-group and the polysiloxane, and by giving greater control over the number of silicon-atoms in the polysiloxane that are connected to a salt-group. In some embodiments, the method of making ionic liquids, and the ionic liquids produced thereby, can advantageously be better suited for membrane applications than other ionic liquids or methods of making the same. Better control and greater options for the chemical group that links the salt-group to the polymer, or better control over the proportion of silicon atoms in a polysiloxane polymer that are bound to a salt-group, allows for finer control over the properties of the resulting membrane. In some examples, the method of the present invention can allow synthesis of polysiloxanes having silicon-pendant salt-groups on a greater number of siloxane units, and with a higher degree of control, than other methods.

DETAILED DESCRIPTION OF THE INVENTION

[0008] Reference will now be made in detail to certain claims of the disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that the exemplified subject matter is not intended to limit the claims to the disclosed subject matter.

[0009] Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of "about 0.1 % to about 5%" or "about 0.1 % to 5%" should be interpreted to include not just about 0.1 % to about 5%, but also the individual values (e.g., 1 %, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1 % to 0.5%, 1 .1 % to 2.2%, 3.3% to 4.4%) within the indicated range. The statement "about X to Y" has the same meaning as "about X to about Y," unless indicated otherwise. Likewise, the statement "about X, Y, or about Z" has the same meaning as "about X, about Y, or about Z," unless indicated otherwise.

[0010] In this document, the terms "a," "an," or "the" are used to include one or more than one unless the context clearly dictates otherwise. The term "or" is used to refer to a nonexclusive "or" unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Any use of section headings is intended to aid reading of the document and is not to be interpreted as limiting; information that is relevant to a section heading may occur within or outside of that particular section. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0011] In the methods of manufacturing described herein, the steps can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited.

[0012] Furthermore, specified steps can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed step of doing X and a claimed step of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

[0013] The term "about" can allow for a degree of variability in a value or range, for example, within 10%, within 5%, or within 1 % of a stated value or of a stated limit of a range.

[0014] The term "organic group" as used herein refers to but is not limited to any carbon-containing functional group. Examples include acyl, cycloalkyl, aryl, aralkyl, heterocyclyl, heteroaryl, or heteroarylalkyl, linear and/or branched groups such as alkyl groups, fully or partially halogen-substituted haloalkyl groups, alkenyl groups, alkynyl groups, acrylate and methacrylate functional groups; and other organic functional groups such as ether groups, cyanate ester groups, ester groups, carboxylate salt groups, and masked isocyano groups. [0015] The term "substituted" as used herein refers to an organic group as defined herein or molecule in which one or more hydrogen atoms contained therein are replaced by one or more non-hydrogen atoms. The term "functional group" or "substituent" as used herein refers to a group that can be or is substituted onto a molecule, or onto an organic group. Examples of substituents or functional groups include, but are not limited to, any organic group, a halogen (e.g., F, CI, Br, and I); a sulfur atom in groups such as thiol groups, alkyl and aryl sulfide groups, sulfoxide groups, sulfone groups, sulfonyl groups, and sulfonamide groups; a nitrogen atom in groups such as amines, hydroxylamines, nitriles, nitro groups, N-oxides, hydrazides, azides, and enamines; and other heteroatoms in various other groups.

[0016] The term "alkyl" as used herein refers to straight chain and branched alkyl groups and cycloalkyi groups having from 1 to about 20 carbon atoms, and typically from 1 to 12 carbons or, in some embodiments, from 1 to 8 carbon atoms. Examples of straight chain alkyl groups include those with from 1 to 8 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl, n- heptyl, and n-octyl groups. Examples of branched alkyl groups include, but are not limited to, isopropyl, isobutyl, sec-butyl, t-butyl, neopentyl, isopentyl, and 2,2-dimethylpropyl groups. As used herein, the term "alkyl" encompasses all branched chain forms of alkyl. Representative substituted alkyl groups can be substituted one or more times with any functional group, for example, amino, hydroxy, cyano, carboxy, nitro, thio, alkoxy, and halogen groups.

[0017] The term "aryl" as used herein refers to cyclic aromatic hydrocarbons that do not contain heteroatoms in the ring. Thus aryl groups include, but are not limited to, phenyl, azulenyl, heptalenyl, biphenyl, indacenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, naphthacenyl, chrysenyl, biphenylenyl, anthracenyl, and naphthyl groups. In some embodiments, aryl groups contain about 6 to about 14 carbons in the ring portions of the groups. Aryl groups can be unsubstituted or substituted, as defined herein. Representative substituted aryl groups can be mono-substituted or substituted more than once, such as, but not limited to, 2-, 3-, 4-, 5-, or 6-substituted phenyl or 2-8 substituted naphthyl groups, which can be substituted with carbon or non-carbon groups.

[0018] The term "resin" as used herein refers to polysiloxane material of any viscosity that includes at least one siloxane monomer that is bonded via a Si-O- Si bond to three or four other siloxane monomers. In one example, the polysiloxane material includes T or Q groups, as defined herein. [0019] The term "radiation" as used herein refers to energetic particles travelling through a medium or space. Examples of radiation are visible light, infrared light, microwaves, radio waves, very low frequency waves, extremely low frequency waves, thermal radiation (heat), and black-body radiation.

[0020] The term "cure" as used herein refers to exposing to radiation in any form, heating, or allowing to undergo a physical or chemical reaction that results in hardening or an increase in viscosity.

[0021] The term "pore" as used herein refers to a depression, slit, or hole of any size or shape in a solid object. A pore can run all the way through an object or partially through the object. A pore can intersect other pores.

[0022] The term "free-standing" or "unsupported" as used herein refers to a membrane with the majority of the surface area on each of the two major sides of the membrane not contacting a substrate, whether the substrate is porous or not. In some embodiments, a membrane that is "free-standing" or

"unsupported" can be 100% not supported on both major sides. A membrane that is "free-standing" or "unsupported" can be supported at the edges or at the minority (e.g. less than about 50%) of the surface area on either or both major sides of the membrane.

[0023] The term "supported" as used herein refers to a membrane with the majority of the surface area on at least one of the two major sides contacting a substrate, whether the substrate is porous or not. In some embodiments, a membrane that is "supported" can be 100% supported on at least one side. A membrane that is "supported" can be supported at any suitable location at the majority (e.g. more than about 50%) of the surface area on either or both major sides of the membrane.

[0024] The term "enrich" as used herein refers to increasing in quantity or concentration, such as of a liquid, gas, or solute. For example, a mixture of gases A and B can be enriched in gas A if the concentration or quantity of gas A is increased, for example by selective permeation of gas A through a membrane to add gas A to the mixture, or for example by selective permeation of gas B through a membrane to take gas B away from the mixture.

[0025] The term "deplete" as used herein refers to decreasing in quantity or concentration, such as of a liquid, gas, or solute. For example, a mixture of gases A and B can be depleted in gas B if the concentration or quantity of gas B is decreased, for example by selective permeation of gas B through a membrane to take gas B away from the mixture, or for example by selective permeation of gas A through a membrane to add gas A to the mixture.

[0026] The term "solvent" as used herein refers to a liquid that can dissolve a solid, liquid, or gas. Nonlimiting examples of solvents are silicones, organic compounds, water, alcohols, ionic liquids, and supercritical fluids.

[0027] The term "selectivity" or "ideal selectivity" as used herein refers to the ratio of permeability of the faster permeating gas over the slower permeating gas, measured at room temperature. Unless otherwise designated, "selectivity" as used herein designates ideal selectivity.

[0028] The term "permeability" as used herein refers to the permeability coefficient (P _x ) of substance X through a membrane, where q _mx = P _x ^* A ^* Δρ _χ

^* (1 /δ), where q _mx is the volumetric flow rate of substance X through the membrane, A is the surface area of one major side of the membrane through which substance X flows, Δρ _χ is the difference of the partial pressure of substance X across the membrane, and δ is the thickness of the membrane. P _x can also be expressed as V-5/(A-t-Ap), wherein P _x is the permeability for a gas

X in the membrane, V is the volume of gas X which permeates through the membrane, δ is the thickness of the membrane, A is the area of the membrane, t is time, Δρ is the pressure difference of the gas X at the retente and permeate side. Permeability is measured at room temperature, unless otherwise indicated.

[0029] The term "Barrer" or "Barrers" as used herein refers to a unit of permeability, wherein 1 Barrer = 10 ^" ^ (cm ³ gas) cm cm ^-2 s ^~ 1 mmHg ^"' ' , or 10 ^"

^{1 0} (cm ³ gas) cm cm ^-2 s ^"1 cm Hg ^~1 , where "cm ³ gas" represents the quantity of the gas that would take up one cubic centimeter at standard temperature and pressure.

[0030] The term "air" as used herein refers to a mixture of gases with a composition approximately identical to the native composition of gases taken from the atmosphere, generally at ground level.

[0031] The term "room temperature" as used herein refers to ambient temperature, which can be, for example, between about 15 °C and about 28 °C.

[0032] The term "coating" refers to a continuous or discontinuous layer of material on the coated surface, wherein the layer of material can penetrate the surface and can fill areas such as pores, wherein the layer of material can have any three-dimensional shape, including a flat or curved plane. In one example, a coating can be formed on one or more surfaces, any of which may be porous or nonporous, by immersion in a bath of coating material.

[0033] The term "surface" refers to a boundary or side of an object, wherein the boundary or side can have any perimeter shape and can have any three- dimensional shape, including flat, curved, or angular, wherein the boundary or side can be continuous or discontinuous.

[0034] The term "mil" as used herein refers to a thousandth of an inch, such that 1 mil = 0.001 inch = 25.4 microns.

[0035] The present invention relates to silicone-based ionic liquids and methods of making the same, curable compositions that include the same, materials such as membranes made therefrom, and methods of using those materials. Various embodiments of the present invention provide a curable composition. The curable composition includes Component (A), an organic compound having at least one free-radical polymerizable group per molecule. The curable composition also includes Component (B), a mercapto-functional organic compound having an average of at least about three mercapto groups per molecule. The curable composition also includes Component (C), a polysiloxane having an average of at least about one phosphonium group or ammonium group per molecule, wherein the polysiloxane has an average of at least about five Si atoms per molecule. Additionally, the curable composition includes a catalytic amount of a free-radical initiator. The curable composition can be cured via any suitable method, for example via thiol-ene chemistry. In some embodiments, the present invention provides a method of separating gas components in a feed gas mixture using a membrane that includes a cured product of the curable composition.

[0036] In some examples, Component (A), the organic compound having at least one free-radical polymerizable group per molecule, can be present in from about 5 wt% to about 50 wt%, about 10 wt % to about 35 wt%, or about 20 wt% to about 25 wt% of the curable composition. Wt% in this paragraph refers to the percent by weight based on the total weight of Components (A), (B), (C), and (D).

[0037] In some examples, Component (B), the mercapto-functional organic compound having an average of at least about three mercapto groups per molecule can be present in from about 1 wt% to about 30 wt%, about 3 wt % to about 15 wt%, or about 5.5 wt% to about 7.5 wt% of the curable composition. Wt% in this paragraph refers to the percent by weight based on the total weight of Components (A), (B), (C), and (D).

[0038] In some examples, Component (C), the polysiloxane having an average of at least about one phosphonium group or ammonium group per molecule, can be present in from about 10 wt% to about 99 wt%, about 40 wt% to about 90 wt%, or about 55 wt% to about 75 wt% of the curable composition. Wt% in this paragraph refers to the percent by weight based on the total weight of Components (A), (B), (C), and (D).

[0039] In some examples, Component (D), the free-radical initiator can be present in from about 0.1 wt% to about 6 wt%, or about 1 wt % to about 3 wt% of the curable composition, based on the weight based on the total weight of Components (A), (B), (C), and (D).

Component (A). Organic Compound having at least One Free-Radical Polymerizable Group per Molecule.

[0040] The curable composition includes Component (A), an organic compound having at least one free-radical polymerizable group per molecule. Component (A) can be any suitable organic compound having any suitable number of independently selected suitable free-radical polymerizable group per molecule, such that the composition is curable.

[0041 ] The free-radical curable composition can include an organic compound with at least one free-radical polymerizable group. The free-radical polymerizable group of Component (A) can be any suitable free-radical polymerizable group. The organic compound can have any suitable number of free-radical polymerizable groups, such as about one, two, three, four, about five, or more. Examples of free-radical polymerizable groups include, for example, alkenyl groups and alkynyl groups, as well as groups such as ethers, ketones, aldehydes, carboxylates, ketals, acetals, cyano groups, nitro groups, or halogens.

[0042] In some examples, the free-radical polymerizable group of Component (A) can be any suitable free-radical polymerizable group. In some examples, the free-radical polymerizable group of Component (A) can have the formula

CR ¹ R ¹ =CR ¹ -C(=0)-, wherein each R ¹ is independently C-| -C-| Q hydrocarbyl or hydrogen. In various embodiments, the one or more free-radical polymerizable group of Component (A) is an alkene having two hydrogen-groups bound at one terminus, allowing easy steric accessibility of for polymerization. In various examples, Component (A) can be an allyl triazine, allyl isocyanurate, acrylate, unsaturated ester, maleimide, methacrylate, acrylonitrile, styrene, diene, or an N-vinyl amide. Generally, but not always, reactivity can be selected based on the electron density of the double bond, where higher density can correspond to higher reactivity.

[0043] For example, the free-radical polymerizable group of Component (A) can be acrylic acid

O

OH ,

1 ,3,5-triallyl-1 ,3,5-triazine-2

or diallylimidazolium chlori 3-ium chloride)

cr

Component (B). Mercapto-Functional Organic Compound having an Average of at least About Three Mercapto Groups per Molecule

[0044] The curable composition includes Component (B), a mercapto-functional organic compound having an average of at least about two mercapto (thiol) groups per molecule. In some embodiments, the mercapto-functional organic compound can have an average of at least three mercapto groups per molecule. The organic compound can be any suitable organic compound. Component (B) can have any suitable average number of mercapto groups per molecule, such as about one, two, three, four, five, or more than about five.

[0045] Component (B) can participate in a polymerization reaction with

Component (A) via thiol-ene chemistry, for example via a free-radical mechanism. In such a polymerization, for example, a thiol group can add across an alkenyl group to generate a sulfur-substituted alkane, or in another example a thiol group can add across an alkynyl group to generate a sulfur- substituted alkene. In some examples, free-radical polymerizable groups of Component (A) can participate in multiple propagation steps prior to termination of the polymerization, such that several free-radical polymerizable groups are joined via the polymerization, including in some examples non-alkenyl or non- alkynyl groups. In other examples, a thiol group can add across a single alkene or alkyne, without multiple propagation steps.

[0046] In various examples, the mercapto-functional organic compound can be an alkyl 3-mercaptopriopionate

O

Rl

O ^ SH

an alkyl thioglycolate

or an alkylthiol,

wherein R ¹ is any organic group of suitable valence (e.g. can be mono-, di-, tri-, tetra-, or poly-substituted), such as a C-| -C-| Q alkyl group or ether, and n can be between 1 and 100.

[0047] In some examples, the mercapto-functional organic compound can be trimethylolpropane tris(3-mercaptopropionate), also referred to as 2-ethyl-2-(((3- mercaptopropano ptopropanoate),

Component (C). Polysiloxane having an Average of at least About One Phosphonium Group or Ammonium Group per Molecule

[0048] The curable composition includes Component (C), a polysiloxane having an average of at least about one phosphonium group or ammonium group per molecule. Component (C) can be any suitable polysiloxane having at least one phosphonium group or ammonium group. In some examples, the polysiloxane has an average of at least about two phosphonium groups or ammonium groups per molecule. In some examples, the polysiloxane has an average of at least about five silicon atoms per molecule. [0049] In some embodiments, the Component (C) can be held in place in the cured product of the curable composition via a polymeric matrix formed by polymerization of one or more of the other components of the curable composition. In some examples, Component (C) is held in place passively, such that other bonding interactions between Component (C) and the polymeric matrix do not occur. In some embodiments, reactive moieties on the polysiloxane, such as bound to the silicon atoms or bound to the phosphonium or ammonium group, can participate in a curing process of the curable composition such that Component (C) is bound to and part of the polymeric matrix formed by polymerization of one or more of the other components of the curable composition. In some embodiments, other suitable interactions can occur between Component (C) and the polymeric matrix formed by

polymerization of one or more of the other components of the curable composition, such that Component (C) is held in place not merely passively in the resulting polymeric matrix but also via other interactions with the polymeric matrix. In some examples, Component (C) can undergo an ion-exchange process such that it bonds to the polymeric matrix. In some examples, acidic moieties in the matrix such as polyacrylic acid (including copolymers thereof) can form compounds between the acidic proton and the counter-ion of the ionic liquid (e.g. halogen such as CI ^" , to release HCI), which can allow the ammonium or phosphonium ion to electrostatically bond to the anionic conjugate base of the acid (e.g. carboxylate ion).

(a) General structure of polysiloxane having a phosphonium group or an ammonium group

[0050] In some examples, the polysiloxane having an average of at least about one phosphonium group or ammonium group per molecule can be an organopolysiloxane. The organopolysiloxane compound can have a linear, branched, cyclic, or resinous structure. The organopolysiloxane compound can be a homopolymer or a copolymer. The organopolysiloxane compound can be a disiloxane, trisiloxane, or polysiloxane. The organopolysiloxane can have an average of at least 5 silicon atoms per molecule. In some examples, the organopolysiloxane can have about 2 silicon atoms per molecule, or about 5, 7, 1 0, 12, 15, 17, 20, 22, 25, 27, 30, 35, 40, 45, 50, 75, 100, 125, 150, 175, 200, 220 or greater than about 220 silicon atoms per molecule, such as about 220 to about 2000 silicon atoms per molecule. In one example, the

organopolysiloxane has about 12 to about 220 Si atoms per molecule. [0051] In one example, an organopolysiloxane can include a compound of the formula

(a) R ¹ ₃ SiO(R ¹ ₂ SiO) _a (R ¹ R ² SiO) _p SiR ¹ ₃ , or

(b) R4R3 ₂ SiO(R3 ₂ SiO) _% (R3R4SiO) ₅ SiR3 ₂ R ⁴ .

[0052] In formula (a), a has an average value of about 0 to about 2000, and β has an average value of about 1 to about 2000. Each R ¹ is independently a monovalent functional group. Suitable monovalent functional groups include, but are not limited to, acrylic groups; alkyl; halogenated hydrocarbon groups; alkenyl; alkynyl; aryl ; and cyanoalkyl. Each R ² is independently a phosphonium group or ammonium group, or R ¹ . In another example, a siloxy-unit can be di- substituted with a phosphonium group or ammonium group.

[0053] In formula (b), χ has an average value of 0 to 2000, and δ has an average value of 1 to 2000. Each R ³ is independently a monovalent functional group. Suitable monovalent functional groups include, but are not limited to, acrylic groups; alkyl; halogenated hydrocarbon groups; alkenyl; alkynyl; aryl; and cyanoalkyl. Each R ⁴ is independently a phosphonium group or ammonium group, or R ³ . In another example, a siloxy-unit can be di-substituted with a phosphonium group or ammonium group, or a siloxy-end-unit can be mono-, di-, or tri-substituted with a phosphonium group or ammonium group.

[0054] The organopolysiloxane compound can be a single organopolysiloxane or a combination including two or more organopolysiloxanes that differ in at least one of the following properties: structure, viscosity, average molecular weight, siloxane units, and sequence.

[0055] Examples of organopolysiloxanes can include compounds having the average unit formula

(R1 R4R5si0 _{1 /2} ) _w (Rl R4Si0 ₂ / ₂ ) _x (R4Si0 ₃ / ₂ ) _y (SiC>4/ ₂ ) _z (I), wherein R ¹ is a functional group independently selected from any optionally further substituted C-i .-^ functional group, including C-i .-^ monovalent aliphatic hydrocarbon groups, 04.-15 monovalent aromatic hydrocarbon groups, and monovalent epoxy-substituted functional groups, R ⁴ is a phosphonium group or ammonium group or R^ or R^ , R^ is R^ or R ⁴ , 0<w<0.95, 0<x<1 , 0<y<1 , 0<z<0.95, and w+x+y+z∞1 . In some embodiments, R^ is C-\ .-\ Q hydrocarbyl or C-| _-| o halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, or C4-14 aryl. In some embodiments, w is from 0.01 to 0.6, x is from 0 to 0.5, y is from 0 to 0.95, z is from 0 to 0.4, and w+x+y+z∞1 . In other examples, a siloxy unit can be mono-, di-, or tri -substituted with a phosphonium group or ammonium group.

[0056] In descriptions of average unit formula, such as formula I, the subscripts w, x, y, and z are mole fractions. It is appreciated that those of skill in the art understand that for the average unit formula (I), the variables R ¹ , R ⁴ , and R ⁵ can independently vary between individual siloxane formula units. Alternatively, the variables R^ , R ⁴ , and R^ can independently be the same between individual siloxane formula units. For example, average unit formula (I) above can include the following average unit formula:

(Rl R4R5si0 ₁ /2)w(R ^{1 a} R ⁴ Si02/2)xi (R ^{1 b} R ⁴ Si02/2)x2(R ⁴ Si0 ₃ /2) _y (Si04/2)z wherein subscripts x1 +x2 = x, and where R^ ^a is not equal to R ^" " ³ . Alternatively, R ^{1 a} can be equal to R ^{1 b} .

(b) Phosphonium group or ammonium group

[0057] In one example, the phosphonium group or ammonium group can be directly bound to a silicon atom of the polysiloxane. In another example, the phosphonium group or ammonium group can be bound to a silicon atom of the polysiloxane via linking group, wherein the linking group can be any suitable linking group. For example, the linking group can be any organic group, such as any C-\ _20 group, including any alkyl, alkenyl, aryl, heteroaryl, acyl, amine, ether, amide, or any combination thereof. In some embodiments, a linking group can separate the phosphonium group or ammonium group from the polysiloxane by about 2 atoms, 3, 4, 5, 6, 7, 8, 9, 1 0, 1 1 , 12, 13, 14, 15, 16, 17, 18, 19, 20, or more than about 20 atoms. In some embodiments, a shorter linker can be preferable (e.g. about 2-5 atoms, or about 3-7 atoms, or about 4-9 atoms separating the polysiloxane from the phosphonium or ammonium ion), for example because as the proportion of silicon gets lower in the polysiloxane, the gas permeability of a membrane made therefrom can become less. However, in other embodiments, a longer linker (e.g. 10-20 atoms separating the polysiloxane from the phosphonium or ammonium ion) can be preferable.

[0058] The phosphonium group can be any suitable phosphonium group. For example, the phosphonium group can be any +1 charged quaternary phosphorus atom, substituted with two to four substituents (with four bonds to the phosphorus atom total, e.g. four single bonds, two single bonds and one double bond, two double bonds), for example the substitutents can be independently selected from H, C-| -C-| Q alkyl or aryl, or can form any suitable heterocyclic ring including the ammonium-nitrogen atom

[0059] The ammonium group can be any suitable ammonium group. For example, the ammonium group can include any +1 charged quaternary nitrogen atom, substituted with two to four substitutents (with four bonds to the nitrogen atom total, e.g. four single bonds, two single bonds and one double bond, two double bonds), for example the substitutents can be independently selected from H, C-| -C-| rj alkyl or aryl, and can together form any suitable heterocyclic ring including the ammonium-nitrogen atom. In some examples, the ammonium group can be an imidazolium group. An imidazolium group can be N- substituted with any suitable organic group, such as any C-j ^o alkyl, alkenyl, or alkynyl group.

[0060] The phosphonium group or quaternary ammonium group can include any suitable -1 charged counterion, such as any deprotonated C-| -C20 carboxylic acid, F ^" , CI ^" , Br, Γ, N0 ₃ ^" , HSO4-, N0 ₂ ^" , CIO4-, IO3-, CIO3-, Br0 ₃ ^" ,

CI0 ₂ ^" , OCI-, OBr, HCO3-, CN ^" , OCN ^" , OH ^" , MnO^, and the like.

[0061] An organopolysiloxane compound can have any suitable average number of phosphonium or ammonium groups per molecule, the properties of cured product of the curable composition are as desired. For example, the polysiloxane can have an average of at least about one phosphonium group or ammonium group per molecule, or an average of less than about 1 , or an average of about 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30, 50, 100, 150, 200, 250, 300, 350, or about 400 phosphonium groups or ammonium groups per molecule, or an average of greater than about 400 phosphonium groups or ammonium groups per molecule.

[0062] In some embodiments, the phosphonium or ammonium group can have a substituent that allows further reaction, such as an alkyl group having at least one unsaturated C-C bond, such as an alkenyl or alkynyl group, such as a Q>2-

12 alkenyl or alkynyl group. In various embodiments, the at least one unsaturated C-C bond can participate in the curing process, for example by participating in a thiol-ene polymerization reaction with the other components of the curable composition.

[0063] In some examples, a pendant alkenyl group on a phosphonium or ammonium group can be allowed to react via an olefin metathesis in the presence of an appropriate catalyst, such as for example a Grubbs, Hoveyda, Grubbs-Hoveyda, or other related catalyst, and in the presence of an appropriate reagent, such as a suitably substituted alkene.

(c) Methods of making the orqanopolysiloxane having an average of at least about one phosphonium group or ammonium group per molecule

[0064] Any suitable method can be used to make the organopolysiloxane having an average of at least about one phosphonium group or ammonium group per molecule. The methods of making the organopolysiloxane given herein are merely examples, and the suitable methods of making the organopolysiloxane can encompass methods beyond those given herein.

[0065] In one example, the organopolysiloxane can be made using a suitable organohydrogenpolysiloxane. In some examples, the

organohydrogenpolysiloxane can be a suitable polymethylhydrogensiloxane (PMHS) or polymethylhydrogensiloxane-polydimethylsiloxane copolymer (PMHS-PDMS) copolymer. Examples of suitable organohydrogenpolysiloxanes include any organopolysiloxane described in section (a), describing the general structure of the polysiloxane having a phosphonium group or a ammonium group, but wherein all of the phosphonium groups and ammonium groups are replaced by H-groups, such that the polysiloxane is an

organohydogenpolysiloxane. In such examples, the

organohydrogenpolysiloxane can have the same number of Si-H groups as the number of phosphonium or ammonium groups possessed by the product polysiloxane. In other embodiments, suitable organohydrogenpolysiloxanes can include any organopolysiloxane described in section (a), describing the general structure of the polysiloxane having a phosphonium group or a ammonium group, but wherein all of the phosphonium groups and ammonium groups are replaced by H-groups, and additionally wherein any other suitable number of Si- R groups are replaced by Si-H groups. In such an embodiment, the organohydrogenpolysiloxane can have a greater number of Si-H groups than the number of phosphonium or ammonium groups possessed by the product polysiloxane. [0066] The organohydrogenpolysiloxane can be allowed to react with a terminally-halide-substituted alkene- or alkyne-containing compound. The halide atom can be substituted on a terminus of the compound. The alkenyl group in the compound can be at a different terminus of the compound than the halide, or can be at a non-terminus position. In one example, the structure of the terminally-halide-substituted compound can be

wherein R ¹ is any suitable monovalent organic group, R ² is any suitable divalent organic group, and X is any suitable halide. In another example, R ¹ and R ² are independently selected from any C-j ^rj alkyl, aryl, alkyl, alkenyl, aryl, heteroaryl, acyl, amine, ether, amide, or any combination thereof, wherein R1 is monovalent, and R ² is divalent, and X is any suitable halide, e.g. F, Br, CI, I. In some examples, the terminally-halide substituted compound can be identical to the structure above but having an alkynyl substituent in place of the alkenyl substituent, and correspondingly having X-R ² - bound to one end of the alkyne and R^ bound to the other. In some examples, the terminally-halide- substituted compound can be 2-chloroethylvinyl ether or 4-bromobutene.

[0067] The terminally-halide substituted compound can be allowed to undergo a hydrosilylation reaction with the organohydrogenpolysiloxane, such that Si-H groups react with the alkenyl or alkynyl group to give an organopolysiloxane compound having a terminally-substituted halogen atom linked via a linker unit to a silicon atom of the polysiloxane. The hydrosilylation reaction can be optionally catalyzed by a suitable amount of hydrosilylation catalyst. The hydrosilylation can be allowed to proceed until a desired amount of Si-H groups have been consumed by the terminally-halide-substituted alkene- or alkyne- containing compound. In some examples, the alkene- or alkyne-containing compound is too unreactive to consume all of the Si-H groups in a suitable period of time, notably alkene- or alkyne-containing compounds wherein the alkene or alkyne group is not at the terminus of the compound, e.g. when the alkene or alkyne is more highly substituted the compound can tend to be less reactive. Si-H groups can be substantially entirely eliminated from the polysiloxane in order to have favorable results from the next chemical step to form the phosphonium or ammonium ion, otherwise undesirable reactions can occur at the Si-H groups. In some examples, the undesirable reactions can lead to gelation or gas evolution (hydrogen).

[0068] In embodiments wherein residual Si-H groups occur on the

organopolysiloxane having terminally halide-substituted pendant groups, the Si- H groups can be eliminated by treatment with a reactive alkene or alkyne to allow a hydrosilylation reaction with the Si-H groups. The reactive alkene or alkyne can be any reactive alkene or alkyne, for example the reactive alkene or alkyne can be a terminally-halide-substituted alkenyl- or alkynyl-containing compound, as described herein, but wherein the compound is more reactive than the first terminally-halide-substituted alkenyl- or alkynyl-containing compound allowed to react with the organohydrogenpolysiloxane (e.g. having a less-substituted alkenyl- or alkynyl-group, or otherwise structurally different to allow higher reactivity with Si-H groups). In some embodiments, the reactive alkenyl or alkyl compound can have no halogen atoms. In some examples, the reactive alkenyl- or alkynyl-containing compound used to substantially eliminate residual Si-H groups can be ethylene, or any suitable vinyl or allyl ether such as for example 2-chloroethylvinyl ether, propyl vinyl ether, allyl propionate, vinyl acetate, or allyl acetate.

[0069] The resulting terminally-substituted halide of the organopolysiloxane can then be allowed to react with a suitable reagent to give a product wherein the halide atom is replaced with a phosphonium or ammonium group, e.g. the silicone-based ionic liquid, an organopolysiloxane having an average of at least about two phosphonium groups or ammonium groups per molecule. Examples of suitable reagents for the preparation of a phosphonium group from the terminal-halide include any tri-C-| _20 alkyl-substituted phosphine, wherein each

Ci -20 alkyl substituent is independently selected, such as triethylphosphine. Examples of suitable reagents for the preparation of an ammonium group from the terminal-halide include any C-\ _20 alkyl substituted imidazole, such as N- butylimidazole.

[0070] Scheme 1 illustrates an example of synthesis of a silicone-based ionic liquid, in accordance with various embodiments, as described herein. In Scheme 1 , a polymethylhydrogensiloxane-polydimethylsiloxane copolymer (PMHS-PDMS) copolymer is allowed to react with 2-chloroethylvinyl ether to give a chloroethoxyethyl-substituted organosiloxane polymer. The terminally- substituted halide is then allowed to react with an N-R-substituted-imidazole to replace the halogen with an imidazolium-group, giving the silicone-based ionic liquid, an imidazole-substituted organopolysiloxane.

[0071] Scheme 1 . Synthesis of a silicone-based ionic liquid, in accordance with various embodiments.

[0072] The curable composition includes Component (D), a free-radical initiator. The free-radical initiator can be any suitable free-radical initiator. The free- radical initiator can be present in a catalytic amount, for example a quantity sufficient to efficiently initiate or promote free-radical chemical reactions in the curable composition. Free-radical polymerization can allow the curable composition to cure. The free-radical photoinitiator can be a single free-radical photoinitiator or a mixture including two or more different free-radical photoinitiators.

[0073] In free-radical curing, for example, a free-radical is generated. The free- radical then can attack a free-radical polymerizable functional group. The attacking group forms a bond to the free-radical polymerizable group, and transfers a radical thereto. The free-radical polymerizable functional group can then go on to attack other free-radical polymerizable functional groups.

[0074] Free-radicals can be generated by any suitable method. Free-radicals can be initiated by, for example, thermal decomposition, photolysis, redox reactions, persulfates, ionizing radiation, electrolysis, plasma, sonication, or a combination thereof. In one example, a free-radical is generated using a free- radical initiator. In one example, the free-radical initiator can be a free-radical photoinitiator, an organic peroxide, or a free-radical initiator activated by heat. Further, a free-radical photoinitiator can be any free-radical photoinitiator capable of initiating cure (cross-linking) of the free-radical polymerizable functional groups upon exposure to radiation, for example, having a wavelength of from 200 to 800 nm. In another example, the free-radical initiator is a organoborane free-radical intiator. In one example, the free-radical initiator can be an organic peroxide. For example, elevated temperatures can allow a peroxide to decompose and form a highly reactive radical, which can initiate free-radical polymerization. In some examples, decomposed peroxides and their derivatives can be byproducts.

[0075] Some examples of suitable free-radical photoinitiators that can be activated by, for example, ultraviolet light, include a-hydroxyketones such as 1 - hydroxy-cyclohexyl-phenyl-ketone, benzophenone, 2-hydroxy-2-methyl-1 - phenyl-1 -propanone, 2-hydroxy-1 -[4-(2-hydroxyethoxy)phenyl]-2-methyl-1 - propanone; phenylglyoxylates such as methylbenzoylformate, oxy-phenyl-acetic acid 2-Γ2 oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester (CAS 211510-16-6), or oxy- phenyl-acetic 2-[2-hydroxy-ethyoxy]-ethyl ester (CAS 442536-99-4) ;

benzyldimethyl-ketals like α,α-dimethoxy-a-phenylacetophenone; a- aminoketones such as 2-benzyl-2-(dimethylamino)-1 -[4-(4-morpholinyl)phenyl- 1 -butanone, 2-methyl-1 -[4-(methylthio)phenyl]-2-(4-morpholinyl)-1 -propanone); mono acyl phosphines (MAPOs) such as diphenyl (2,4,6-trimethylbenzoyl)- phosphine oxide; bis acyl phosphines (BAPOs) such as phenyl bis(2,4,6- trimethyl benzoyl) phosphine oxide; metallocenes such as bis(n5-2,4- cyclopentadien-1 -yl) bis [2,6-difluoro-3-(1 H-pyrrol-1 -yl)phenyl]titanium; or iodonium salts such as (4-methylphenyl), [4-(2-methylpropyl)phenyl] iodonium hexafluorophosphate

[0076] In one example, Darocur 4265 can be used, including components of about 50 wt% diphenyl (2,4 phine oxide

and about 50 wt% 2-hydroxy-2-methyl-1 -phenyl-1 -propanone

Membrane

[0077] In one embodiment, the present invention includes a membrane that includes a cured product of the curable composition. In another embodiment, the present invention provides a method of forming a membrane. The present invention can include the step of forming a membrane. The membrane can be formed on at least one surface of a substrate. For any membrane to be considered "on" a substrate, the membrane can be attached (e.g. adhered) to the substrate, or be otherwise in contact with the substrate without being adhered. The substrate can have any surface texture, and can be porous or non-porous. The substrate can include surfaces that are not coated with the membrane by the step of forming the membrane. All surfaces of the substrate can be coated by the step of forming the membrane, one surface can be coated, or any number of surfaces can be coated.

[0078] In an example, forming a membrane can include two steps. In the first step, the curable composition can be applied to at least one surface of the substrate. In the second step, the applied composition can be cured to form the membrane. In some embodiments, the curing process of the composition can begin before, during, or after application of the composition to the surface. The curing process transforms the curable composition into the membrane. The composition that forms the membrane can be in a liquid state. The membrane can be in a solid state.

[0079] The curable composition be applied using conventional coating techniques, for example, immersion coating, die coating, blade coating, curtain coating, drawing down, solvent casting, spin coating, dipping, spraying, brushing, roll coating, extrusion, screen-printing, pad printing, or inkjet printing.

[0080] Curing the curable composition can include the addition of a curing agent or initiator such as, for example, a hydrosilylation catalyst. In some embodiments, the curing process can begin immediately upon addition of the curing agent or initiator. The addition of the curing agent or initiator may not begin the curing process immediately, and can require additional curing steps. In other embodiments, the addition of the curing agent or initiator can begin the curing process immediately, and can also require additional curing steps. The addition of the curing agent or initiator can begin the curing process, but not bring it to a point where there composition is cured to the point of being fully cured, or of being unworkable. Thus, the curing agent or initiator can be added before or during the coating process, and further processing steps can complete the cure to form the membrane.

[0081] The membrane can have any suitable thickness. In some examples, the membrane can have a thickness of from about 1 μιτι to about 20 μιτι. In some examples, the membrane can have a thickness of from about 0.1 μιτι to about 200 μιτι. In other examples, the membrane can have a thickness of from about 0.01 μιτι to about 2000 μιτι.

[0082] The membrane can be selectively permeable to one substance over another. In one example, the membrane is selectively permeable to one gas over other gases or liquids. In another example, the membrane is selectively permeable to more than one gas over other gases or liquids. In some examples, the membrane has a CO2/CH4 ideal selectivity of at least about 2.8, at least about 3.0, 4, 5, 6, 7, 8, 9, 1 0, 15, 20, 25, 50, 75, 100, 150, 200, 300, 400, 500, 600, 700, 800, 900, 1 000, 2000,3000, 4000, or at least about 5000 at room temperature. In some embodiments, the membrane has an CO2 permeability coefficient of at least about 300 Barrer, 500 Barrer, 700 Barrer, 900 Barrer, 1000 Barrer, 1200 Barrer, 1400 Barrer, 1600 Barrer, 1800 Barrer, 2000 Barrer, 2500 Barrer, or at least about 3000 Barrer at room temperature.

[0083] The membrane of the present invention can be solid, flexible, or any suitable combination thereof. The membrane of the present invention can have any suitable shape. In some examples, the membrane can be a plate-and- frame membrane, spiral wound membrane, tubular membrane, capillary fiber membrane, or hollow fiber membrane. In some embodiments, the membrane can be used in conjunction with a liquid that enhances gas transport, such as in a membrane contactor (e.g. a device that permits mass transfer between a gaseous phase and a liquid phase across a membrane without dispersing the phases in one another).

Supported Membrane

[0084] In some embodiments of the present invention, the membrane is supported on a porous or highly permeable non-porous substrate. A supported membrane has the majority of the surface area of at least one of the two major sides of the membrane contacting a porous or highly permeable non-porous substrate. A supported membrane on a porous substrate can be referred to as a composite membrane, where the membrane is a composite of the membrane and the porous substrate. The porous substrate on which the supported membrane is located can allow gases to pass through the pores and to reach the membrane. The supported membrane can be attached (e.g. adhered) to the porous substrate. The supported membrane can be in contact with the substrate without being adhered. The porous substrate can be partially integrated, fully integrated, or not integrated into the membrane.

[0085] In some examples, a supported membrane can be made by providing a substrate, wherein at least one surface of the substrate includes a plurality of pores or is highly permeable to the materials of interest. The substrate can be any suitable shape, including planar, curved, or any combination thereof.

Examples of porous substrates or highly permeable non-porous substrates includes a sheet, tube or hollow fiber. The porous substrate or highly permeable non-porous substrate can be smooth, be corrugated or patterned, or have any amount of surface roughness. A coating can be formed on the at least one porous surface of the substrate or on the at least one surface of the highly permeable non-porous substrate. Alternately, a porous or highly permeable non-porous substrate can be placed in contact with the formed coating before, during, or after curing of the coating. For example, the porous or highly permeable non-porous substrate can be laid upon an uncured, partially cured or fully cured coating, or drawn through an uncured or fully cured coating. Forming the coating can include applying the coating, and curing the coating. The steps of applying and curing can occur in any order and can occur simultaneously.

[0086] In another example, a supported membrane can be made by providing a substrate, wherein at least one surface of the substrate includes a plurality of pores or is highly permeable to the materials of interest. A first coating can be formed on the at least one porous or highly permeable surface of the substrate. Forming the first coating can include applying the coating, and curing the coating. The first coating can be formed sufficiently to at least partially fill the pores. The first coating can be removed, such that a substantially exposed substrate surface is formed, and such that the cured coating remains at least partially in the pores of the substrate. The first coating can be any suitable material, and can include materials that swell and absorb solvent or water. A second coating can be formed on the exposed substrate surface. Forming the second coating can include applying the coating, and curing the coating. The second coating can include a membrane, where the membrane includes a cured product of a curable composition. The method can further include at least partially restoring the porosity of the porous substrate. For example, in embodiments with a first coating that swells and absorbs solvent or water, the porosity of substrate can be at least partially recovered by drying the first coating to remove the majority of the absorbed solvent or water.

[0087] In another example, the supported membrane is made in a manner identical to that disclosed herein pertaining to a free-standing membrane, but with the additional step of placing or adhering the free-standing membrane on a porous substrate to make a supported membrane.

[0088] The porous substrate can be, for example, a filter, or any substrate of any suitable shape that includes a fibrous structure or any structure. The porous substrate can be woven or non-woven. The porous substrate can be a frit, a porous sheet, or a porous hollow fiber. The porous substrate can be any suitable porous material known to one of skill in the art, in any shape. For example, the at least one surface can be flat, curved, or any combination thereof. The surface can have any perimeter shape. The porous substrate can have any number of surfaces, and can be any three-dimensional shape.

Examples of three-dimensional shapes include cubes, spheres, cones, and planar sections thereof with any thickness, including variable thicknesses. The porous substrate can have any number of pores, and the pores can be of any size, depth, shape, and distribution. In one example, the porous substrate has a pore size of from about 0.2 nm to about 500 μιτι. The at least one surface can have any number of pores. In some examples, the pores size distribution may be asymmetric across the thickness of the porous sheet, film or fiber.

[0089] Suitable examples of porous substrates include porous polymeric films, fibers or hollow fibers, or porous polymers or any suitable shape or form.

Examples of polymers that can form porous polymers suitable for use as a porous substrate in embodiments of the present invention include those disclosed in U.S. Patent No. 7,858,197. For example, suitable polymers include polyethylene, polypropylene, polysulfones, polyamides, polyether ether ketone (PEEK), polyarylates, polyaramides, polyethers, polyarylethers, polyimides, polyetherimides, polyphthalamides, polyesters, polyacrylates,

polymethacrylates, cellulose acetate, polycarbonates, polyacrylonitrile, polytetrafluoroethylene and other fluorinated polymers, polyvinylalcohol, polyvinylacetate, syndiotactic or amorphous polystyrene, Kevlar™ and other liquid crystalline polymers, epoxy resins, phenolic resins, polydimethylsiloxane elastomers, silicone resins, fluorosilicone elastomers, fluorosilicone resins, polyurethanes, and copolymers, blends or derivatives thereof. Polymers that can form porous polymers suitable for use as a porous substrate in

embodiments of the present invention can also include other copolymers or polymeric alloys, which can be two or more miscible or partially miscible polymers, and polymeric blends, which can have discrete non-miscible phases. Examples of polymers that can form porous polymers suitable for use as a porous or highly permeable substrate in embodiments of the present invention include thermoplastic or thermoset polymers, including but not limited to those commonly known in the art. The polymers that can form porous polymers suitable for use as a porous substrate in embodiments of the present invention may be modified with supplemental additives including, but not limited to, antioxidants, coloring agents such as pigments and dyes, flame retardants, process aids, antistatic agents, impact modifiers, nucleating agents, flow aids, ignition resistant additives, coupling agents, lubricants, antiblocking agents, mold release additives, plasticizers, ultraviolet ray inhibitors, or thermal stabilizers.

[0090] Suitable porous substrates can include, for example, porous glass, various forms and crystal forms of porous metals, ceramics and alloys, including porous alumina, zirconia, titania, steel, stainless steel, titanium, aluminum, copper, nickel, zinc, iron, manganese, magnesium, iron, chromium, vanadium, silver, gold, platinum, palladium, rhodium, lead, tin, antimony, silicon, germanium, silicon carbide, tungsten carbide.

Unsupported Membrane

[0091] In some embodiments of the present invention, the membrane is unsupported, also referred to as free-standing. The majority of the surface area on each of the two major sides of a free-standing membrane are not contacting a substrate, whether the substrate is porous or not. In some embodiments, a free-standing membrane can be 100% unsupported. A free-standing membrane can be supported at the edges or at the minority (e.g. less than 50%) of the surface area on either or both major sides of the membrane. The support for a free-standing membrane can be a porous or highly permeable substrate, or a nonporous or non-highly permeable substrate. Examples of suitable supports for a free-standing membrane can include but is not limited to any examples of supports given herein for supported membranes. A free-standing membrane can have any suitable shape, regardless of the percent of the freestanding membrane that is supported. Examples of suitable shapes for freestanding membranes include, for example, squares, rectangles, circles, tubes, cubes, spheres, cones, and planar sections thereof, wherein the free-standing membrane can have any suitable thickness, including variable thicknesses.

[0092] A support for a free-standing membrane can be attached to the membrane in any suitable manner, for example, by clamping, with use of adhesive, by melting the membrane to the edges of the substrate, or by chemically bonding the membrane to the substrate by any suitable means. The support for the free-standing membrane can be unattached to the membrane but nonetheless in contact with the membrane and held in place by friction or gravity or other suitable means. The support can include, for example, a frame around the edges of the membrane, which can optionally include one or more cross-beam supports within the frame. The frame can be any suitable shape, including a square or circle, and the cross-beam supports, if any, can form any suitable shape within the frame. The frame can be any suitable thickness. The support can be, for example, a cross-hatch pattern of supports for the membrane, where the cross-hatch pattern has any suitable dimensions.

[0093] A free-standing membrane can be made, for example, by the steps of coating or applying a curable composition onto a release substrate, curing the composition, and removing the membrane from the release substrate. After application of the composition to the release substrate, the assembly can be referred to as a laminated film or fiber. During or after the curing process the membrane can be at least partially removed from at least one release substrate. In some examples, after the unsupported membrane is removed from a release substrate, the membrane is then attached to a support, as described herein. In some examples, an unsupported membrane is made by the steps of coating a composition onto one or more release substrates, curing the composition, and removing the membrane from at least one of the one or more release substrates, while leaving at least one of the one of more substrates in contact with the membrane. In some embodiments, the membrane is entirely removed from the release substrate. In one example, the membrane can be peeled away from the release substrate. The release substrate can be any suitable release substrate that allows a membrane formed thereon to be removed, such as for example Teflon or another slippery material. [0094] After application of the curable composition, and before, during, or after the curing process, the thickness or shape of the applied composition can be altered via any suitable means, for example leveled or otherwise adjusted, such that the membrane that results after the curing process has the desired thickness and shape. In one example, a doctor blade or drawdown bar is used to adjust the thickness of the applied composition. In another example, a conical die is used to adjust the thickness of the applied composition on a fiber that is later removed.

[0095] In examples that include a substrate, the substrate can be porous or nonporous. The substrate can be any suitable material, and can be any suitable shape or size, including planar, curved, solid, hollow, or any combination thereof. Suitable materials for porous or nonporous substrates include any polymers described above as suitable for use as porous substrates in supported membranes. The substrate can be a water soluble polymer that is dissolved by purging with water. The substrate can be a fiber or hollow fiber, as described in US 6,797,212 B2. In some examples, the substrate is coated with a material prior to formation of the membrane that facilitates the removal of the membrane once formed. The material that forms the substrate can be selected to minimize sticking between the membrane and the substrate. In some examples, the membrane can be heated, cooled, washed, etched or otherwise treated to facilitate removal from the substrate. In other examples, air pressure can be used to facilitate removal of the membrane from the substrate.

Method of Gas Separation

[0096] The present invention also provides a method of separating gas components in a feed gas mixture by use of the membrane described herein. The method includes contacting a first side of a membrane with a feed gas mixture to produce a permeate gas mixture on a second side of the membrane and a retentate gas mixture on the first side of the membrane. The permeate gas mixture is enriched in the first gas component. The retentate gas mixture is depleted in the first gas component.

[0097] The membrane can be free-standing or supported by a porous or permeable substrate. In some embodiments, the pressure on either side of the membrane can be about the same. In other embodiments, there can be a pressure differential between one side of the membrane and the other side of the membrane. For example, the pressure on the retentate side of the membrane can be higher than the pressure on the permeate side of the membrane. In other examples, the pressure on the permeate side of the membrane can be higher than the pressure on the retentate side of the membrane.

[0098] The feed gas mixture can include any mixture of gases. For example, the feed gas mixture can include air, hydrogen, carbon dioxide, nitrogen, ammonia, methane, water vapor, hydrogen sulfide, or any combination thereof. The feed gas can include any gas known to one of skill in the art. The membrane can be selectively permeable to any one gas in the feed gas, or to any of several gases in the feed gas. The membrane can be selectively permeable to all but any one gas in the feed gas.

[0099] Any number of membranes can be used to accomplish the separation. For example, one membrane can be used. In other examples, two, three, four, five, six, seven, eight, nine, ten, or any suitable number of membranes can be used. The membranes need not all include the same reaction product. In some embodiments, all the membranes include the same reaction product. The membranes can have different properties, and can have different permeability for a particular gas. In other embodiments, the membranes have the same properties. Any combination of free-standing and supported membranes can be used.

[00100] The membranes can be manufactured as flat sheets or as fibers and can be packaged into any suitable variety of modules including hollow fibers, sheets or arrays of hollow fibers or sheets. Modules can include hollow fiber modules, spiral wound modules, plate-and-frame modules, tubular modules and capillary fiber modules. The sheets, fibers or leaflets may be of any size or aspect ratio and can assume any packing density in the module. Methods of making hollow fibers modules and spiral wound modules are known in the art, such as described in Baker, R. W. Membrane Technology and Applications, 2nd Edition; 2nd ed. ; John Wiley & Sons Inc. : West Sussex, England, 2004, and in U.S. Patents 3,339,341 and 4,871 ,379 (Maxwell et al. , Edwards et al.) and U.S. Patent 5,034, 126 (Reddy et al.). Various methods and configurations for delivering the feed gas mixture and recovering the permeate and retentate mixtures are also known in the art.

[00101 ] One versed in the art of membrane separations can identify operating conditions for a given combination of membrane performance properties such as selectivity and flux to achieve a desired level of separation optimized on the basis of capital and operating costs, plant footprint, environmental conditions, and maintenance and reliability. The membrane system can be operated in conjunction with compressors, vacuum systems, pre-filters, heaters, chillers, condensers, or any other type of suitable operation either upstream or downstream of the membrane system. The permeate side of the membrane can be operated under a positive pressure, ambient pressure, or negative pressure (e.g. vacuum) with or without a sweep gas or a sweep liquid such as found in a membrane contactor (e.g. a device that permits mass transfer between a gaseous phase and a liquid phase across a membrane without dispersing the phases in one another). The sweep gas can be any gas, and can originate from outside the process or be recycled from within the process, or include a mixture thereof. For example, hollow fiber modules can be fed from the bore side or from the shell side, at any position of entry. The feed gas inlets and permeate gas outlets can be positioned to permit a counter-current, crosscurrent or co-current flow configuration.

[00102] The modules can be operated as single membrane modules or organized further into arrays or banks of modules. The individual membrane modules or arrays or banks of modules can further be configured into additional staged superstructures, such as in series, parallel or cascade configurations, to allow enhanced flux or separation. Partial recycling of the permeate or retentate can be used to achieve a more efficient separation. For example, if the residue stream requires further purification, it may be passed to a second bank of membrane modules for further separation. Likewise, if the permeate stream requires further concentration, it may be passed to a second bank of membrane modules for a second-stage separation. Such multi-stage or multi-step processes, and variants thereof, will be familiar to those of skill in the art, who will appreciate that the membrane separation step may be configured in many possible ways, including single-stage, multistage, multistep, or more complicated arrays of two or more units in serial or cascade arrangements. Optional Ingredients

[00103] Any optional ingredient described herein can be present in the membrane or in the composition that forms the membrane; alternatively, any optional ingredient described herein can be absent from the membrane or the composition that forms the membrane. Without limitation, examples of such optional additional components include surfactants, emulsifiers, dispersants, polymeric stabilizers, crosslinking agents, combinations of polymers, crosslinking agents, catalysts useful for providing a secondary polymerization or crosslinking of particles, rheology modifiers, density modifiers, aziridine stabilizers, cure modifiers such as hydroquinone and hindered amines, free- radical initiators, polymers, diluents, acid acceptors, antioxidants, heat stabilizers, flame retardants, scavenging agents, silylating agents, foam stabilizers, solvents, diluents, plasticizers, fillers and inorganic particles, pigments, dyes and dessicants. Liquids can optionally be used. An example of a liquid includes water, an organic solvent, any liquid organic compound, a silicone liquid, organic oils, ionic fluids, and supercritical fluids. Other optional ingredients include polyethers having at least one alkenyl group per molecule, thickening agents, fillers and inorganic particles, stabilizing agents, waxes or wax-like materials, silicones, organofunctional siloxanes, alkylmethylsiloxanes, siloxane resins, silicone gums, silicone carbinol fluids can be optional components, water soluble or water dispersible silicone polyether compositions, silicone rubber, hydrosilylation catalyst inhibitors, adhesion promoters, heat stabilizers, UV stabilizers, and flow control additives.

[00104] The present invention can be better understood by reference to the following examples which are offered by way of illustration. The present invention is not limited to the examples given herein.

[00105] A variety of methods can be used to measure the permeability of a membrane to particular gases. In the following examples, gas permeability coefficients and ideal selectivities in a binary gas mixture were measured using a permeation cell including upstream (feed/retentate) and downstream

(permeate) chambers that were separated by the membrane. The upstream chamber had one gas inlet and one gas outlet. The downstream chamber had one gas outlet. The upstream chamber was maintained at 35 psig pressure and was continuously supplied with a suitable mixture of CO2 gas and CH4 gas at a flow rate of between 0-200 standard cubic centimeters per minute (seem). The membrane was supported on a glass fiber filter disk with a diameter of 83 mm and a maximum pore diameter range of 10-20 μιτι (Ace Glass). The membrane area was defined by a placing a butyl rubber gasket with a diameter of 50 mm (Exotic Automatic & Supply) on top of the membrane. The downstream chamber was maintained at 5 psig pressure and was continuously supplied with a pure He stream at a flow rate of 20 seem. To analyze the permeability and selectivity of the membrane, the outlet of the downstream chamber was connected to a 6-port injector equipped with a 1 -mL injection loop. On command, the 6-port injector injected a 1 -mL sample into a gas chromatograph (GC) equipped with a thermal conductivity detector (TCD). The amount of gas permeated through the membrane was calculated by calibrating the response of the TCD detector to the gases of interest. The reported values of gas permeability and selectivity were obtained from measurements taken after the system had reached a steady state in which the permeate side gas composition became invariant with time.

[00106] Permeability of gas component i can be calculated by the following equation : Pj=V-5/(A-t-Ap), whereas Pj is the permeability for a gas i in a given membrane, V is the volume of gas which permeates through the membrane, δ is the thickness of the membrane, A is the area of the membrane, t is time, Δρ is the pressure difference of the gas i at the retente and permeation side. Ideal selectivity (a) of gas pair i and j is determined by a=Pj/Pj. Permeance (M) is normalized permeability of gas components: Mj=Pj/ 5.

Example 1 . Synthesis of silicone-based ionic liquid having imidazolium groups.

[00107] To a deaerated mixture of PMHS-PDMS (MW = 13,360, chain length = 220 degree of polymerization, 1 .67 wt% active H content, room temperature viscosity = 240 cSt (mm^/s), 40.0 grams, 0.668 mol) and 2-chloroethylvinyl ether (0.848 mol, 90.4 g) was added H ₂ PtCI ₆ in IPA (10 drops, 0.1 M). The mixture was stirred at ambient temperature for 30 minutes and was

subsequently brought to reflux overnight. 2-Chloroethylvinyl ether was removed in vacuo to afford a yellow oil which was dried in a vacuum oven. To the oil (10.0 grams, 60.0 mmol) in toluene (15 ml_) was added N-butylimidazole (3.81 g, 30.7 mmol). The mixture was brought to reflux overnight. The mixture was cooled to room temperature and taken up in CH2CI2 (30 ml_). The solution was triturated with diethyl ether (300 ml_) to yield a viscous, dark brown oil. Volatiles were removed in vacuo at 65 °C to give a dark, translucent solid.

[00108] Scheme. 1 illustrates a reaction scheme showing synthesis of a silicone-based ionic liquid via hydrosilylation of a organohydrogenpolysiloxane compound using 2-chloroethylvinyl ether wherein the synthesized silicone compounds have imidizolium groups.

Example 2. Synthesis of silicone-based ionic liquid having imidazolium groups.

[00109] To a deaerated solution of polymethylhydrogensiloxane (MW = 14,400, chain length = 220 degree of polymerization, 0.167 wt% active H content, room temperature viscosity = 335 cSt (mm ² /s), 40.0 grams, 67.5 mmol) and 2-chloroethylvinyl ether (0.10 mol, 10.79 g) was added H ₂ PtCI ₆ in IPA (10 drops, 0.1 M). The mixture was stirred at ambient temperature for 10 minutes. The solution was subsequently brought to reflux overnight. 2-Chloroethylvinyl ether was removed in vacuo to afford a brown oil which was dried in a vacuum oven. To the oil (46.4 grams, 64.9 mmol) in toluene (30 mL) was added N- butylimidazole (12.1 g, 97.4 mmol). The mixture was brought to reflux overnight. The mixture was cooled to room temperature and taken up in CH2CI2 (30 mL). The solution was triturated with hexanes (300 mL) to yield a viscous, dark oil. Volatiles were removed in vacuo at 65 °C to give a dark, translucent solid.

Example 3. Synthesis of silicone-based ionic liquid having imidazolium groups.

[00110] To a sample of the adduct of PMHS-PDMS and 2-chloroethylvinyl ether from Example 1 (12 g, 72 mmol CI) was added N-allylimidazole (7.7 g, 70 mmol) in toluene (30 mL). The mixture was brought to reflux overnight. The mixture was cooled to room temperature and taken up in CH2CI2 (30 mL). The solution was triturated with hexanes (300 mL) to yield a viscous, dark oil.

Volatiles were removed in vacuo at 65 °C to give a dark semi-solid.

Example 4. Membrane fabrication and evaluation.

[00111 ] SPIL B (68.2 parts), acrylic acid (17.0 parts), 1 ,3,5-Triallyl-1 ,3,5- triazine-2,4,6(1 H,3H,5H)-trione (6.8 parts), Trimethylolpropane tris(3- mercaptopropionate) (6.8 parts), and Darocur 4265 (about 50 wt% diphenyl

(2,4,6-trimethyl benzoyl)-phosphine oxide and about 50 wt% diphenyl (2,4,6- trimethyl benzoyl)-phosphine oxide) (1 .1 parts) were mixed in SpeedyMixer® thoroughly. The formulations were cast on a polypropylene membrane (pore size=0.2 μιτι, thickness=200 μιτι) and pressed with a hot press (60 °C, 1000 lbs force, 3 seconds). The thin films were then heated to 95 °C for about 5 minutes and cured with UV (3 hours) at ambient conditions. Permeation test was performed at 22 °C. Results were summarized in the table below.

[00112] Table 1 .

Example 5. Membrane fabrication and evaluation.

[00113] SPIL A (59.2 parts), diallylimidazolium chloride (12.3 parts), acrylic acid (14.9 parts), 1 ,3,5-Triallyl-1 ,3,5-triazine-2,4,6(1 H,3H,5H)-trione (6.3 parts), Trimethylolpropane tris(3-mercaptopropionate) (5.9 parts), and Darocur 4265 (about 50 wt% diphenyl (2,4,6-trimethyl benzoyl)-phosphine oxide and about 50 wt% diphenyl (2,4,6-trimethyl benzoyl)-phosphine oxide) (1 .2 parts) were mixed in SpeedyMixer® thoroughly. The formulations were cast on a polyester membrane (pore size=0.2 μιτι, thickness=16 μm) and pressed with a hot press (60 °C, 1000 lbs force, 3 seconds). The thin films were then heated to 95 °C for about 5 minutes and cured with UV (3 hours) at ambient conditions. Permeation test was performed at 22 °C. Results were summarized in the table below.

[00114] Table 3.

groups.

[00115] Following the procedure given in Examples 1 and 2, (2- chloroethoxy)allyl-pedant polysiloxane was made from PMHS-PDMS having MW = 985, chain length = 12 degree of polymerization, 0.80 wt% active H content, room temperature viscosity = 5 cSt (mm ² /s). The polysiloxane obtained had 3.2 CI atoms per molecule. Triethylphosphine (1 .9 ml_, 1.54 g) and the (2-chloroethoxy)allyl-pedant polysiloxane (3.0 g) were charged to a flask under nitrogen protection. The system was deaerated a couple of times and anhydrous toluene (10 ml_) was added. The reaction was brought to reflux and heated overnight to yield a yellow precipitate. The solid was collected via vacuum filtration and dried in vacuum. 31 p NMR indicated a single

phosphonium salt in the yellow solid. ³¹ P NMR (DMSO-dg) δ 42.35 ppm. Triethylphosphine: ³¹ P NMR (DMSO-d ₆ ) δ -20.

[00116] The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention that in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the invention claimed. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art, and that such modifications and variations are considered to be within the scope of this invention as defined by the appended claims.

Additional Embodiments.

[00117] The present invention provides for the following exemplary embodiments, the numbering of which is not to be construed as designating levels of importance:

[00118] Embodiment 1 provides a curable composition comprising: (A) an organic compound having at least one free-radical polymerizable group per molecule; (B) a mercapto-functional organic compound having an average of at least about three mercapto groups per molecule; (C) a polysiloxane having an average of at least about one quaternary phosphonium group or quaternary ammonium group per molecule, wherein the polysiloxane has an average of at least about five silicon atoms per molecule; and (D) a free-radical initiator.

[00119] Embodiment 2 provides the curable composition according to Embodiment 1 , wherein the free-radical polymerizable group of Component (A) has the formula CR^ =CR^ -C(=0)-, wherein each is independently C-| - C-| o hydrocarbyl or hydrogen.

[00120] Embodiment 3 provides the curable composition according to any one of Embodiments 1 or 2, wherein the phosphonium group has a cyclic structure.

[00121 ] Embodiment 4 provides the curable composition according to any one of Embodiments 1 or 2, wherein the quaternary ammonium group has a cyclic structure.

[00122] Embodiment 5 provides the curable composition according to any one of Embodiments 1 -4, wherein the quaternary ammonium group comprises an imidazolium ion.

[00123] Embodiment 6 provides the curable composition according to any one of Embodiments 1 -5, wherein the polysiloxane has an average of from about 5 to about 2000 Si atoms per molecule.

[00124] Embodiment 7 provides the curable composition according to any one of Embodiments 1 -6, wherein the polysiloxane has an average of from about 12 to about 220 Si atoms per molecule.

[00125] Embodiment 8 provides the curable composition according to any one of Embodiments 1 -7, wherein the quaternary phosphonium group or quaternary ammonium group comprises a C2-12 group that includes at least one unsaturated carbon-carbon bond. [00126] Embodiment 9 provides a cured product of the curable composition according to any one of Embodiments 1 -8.

[00127] Embodiment 10 provides an unsupported membrane comprising the cured product according to Embodiment 9, wherein the membrane is free- standing.

[00128] Embodiment 1 1 provides the unsupported membrane according to Embodiment 10, wherein the membrane has a thickness of from 0.1 to 200 μιτι.

[00129] Embodiment 12 provides the unsupported membrane according to any one of Embodiments 10 or 1 1 , wherein the membrane is selected from a plate membrane, a spiral membrane, tubular membrane, and hollow fiber membrane.

[00130] Embodiment 13 provides a coated substrate, comprising: a substrate; and a coating on the substrate, wherein the coating comprises the cured product according to Embodiment 9.

[00131 ] Embodiment 14 provides the coated substrate according to

Embodiment 13, wherein the substrate is porous and the coating is a membrane.

[00132] Embodiment 15 provides the coated substrate according to

Embodiment 14, wherein the porous substrate is a frit comprising a material selected from glass, ceramic, alumina, a porous polymer, and combinations thereof.

[00133] Embodiment 16 provides a method of separating gas components in a feed gas mixture, the method comprising: contacting a first side of a membrane comprising a cured product of a curable composition with a feed gas mixture comprising at least a first gas component and a second gas component to produce a permeate gas mixture on a second side of the membrane and a retentate gas mixture on the first side of the membrane, wherein the permeate gas mixture is enriched in the first gas component, the retentate gas mixture is depleted in the first gas component, and wherein the curable composition comprises (A) an organic compound having at least one free-radical polymerizable group per molecule; (B) a mercapto-functional organic compound having an average of at least about three mercapto groups per molecule; (C) an polysiloxane having an average of at least about one quaternary phosphonium group or quaternary ammonium group per molecule, wherein the polysiloxane has an average of at least about five Si atoms per molecule; and (D) a free- radical initiator. [00134] Embodiment 17 provides the method according to Embodiment 16, wherein the permeate gas mixture comprises carbon dioxide and the feed gas mixture comprises at least one of nitrogen and methane.

[00135] Embodiment 18 provides the method according to any one of Embodiments 16-17, wherein the free-radical polymerizable group of

Component (A) has the formula CR R =CR ¹ -C(=0)-, wherein each R is independently C- _| -C- _| Q hydrocarbyl or hydrogen.

[00136] Embodiment 19 provides the method according to any one of Embodiments 16-18, wherein the polysiloxane has an average of from about 5 to about 2000 Si atoms per molecule.

[00137] Embodiment 20 provides the method according to any one of Embodiments 16-19, wherein the quaternary ammonium group comprises an imidazolium ion.

[00138] Embodiment 21 provides the apparatus or method of any one or any combination of Embodiments 1 -20 optionally configured such that all elements or options recited are available to use or select from.