Ionomers, curable film precursor compositions, film compositions, and electronic devices

Abstract

A cationic copolymer comprises divalent monomer units: and wherein: each Ar 1 independently represents a phenylene group; each L independently represents a direct bond or wherein each R 1 independently represents an alkyl group having 1 to 4 carbon atoms, and each R 2 independently represents an alkylene group having 1 to 6 carbon atoms, and each Z ‑ represents a non-interfering anion; each Ar 2 independently represents an optionally substituted divalent aromatic ring, with the proviso that if L represents a direct bond, Ar 2 represents an optionally substituted cationic divalent aromatic ring, said cationic divalent aromatic ring bearing Z ‑ ; each R 3 independently represents H or an alkyl group having 1 to 6 carbon atoms; and each D independently represents a direct bond or Ar 2 , wherein adjacent D and L are not both direct bonds, and wherein if L is a direct bond, D is Ar 2 . The cationic copolymer can be free-radiation cured and used in films.

Description

[0001] Governmental rights

[0002] This invention was made with government support under Cooperative Agreement DE-AR0000950 awarded by the U.S. Department of Energy. The government has certain rights in the invention. BACKGROUND

[0003] Anion exchange membranes can be used in a variety of electrochemical cells, such as, for example, fuel cells, electrolyzers, batteries, and electrodialysis cells. Previous anion exchange membranes have been prepared from various copolymers having cationic nitrogen-containing groups. These copolymers have been prepared, for example, by reacting a styrene-co-vinylbenzyl chloride copolymer with various nitrogen-containing bases to provide the corresponding quaternary ammonium groups. The mechanical strength of typical membranes formed in this way is insufficient for use in applications such as those described above. For example, the membranes are often brittle and have low tensile strength. In addition, some membranes are susceptible to hydrolytic degradation. SUMMARY

[0004] In anion exchange membranes for carbon dioxide or water electrolysis, fuel cells, flow batteries, and similar electrochemical devices, reinforcement and hydrolytic stability are desirable. The present disclosure provides ionic copolymers suitable for inclusion in anion exchange membranes, which can overcome the above-described deficiencies of existing anion exchange membranes. The present disclosure provides materials and methods for preparing ionic membranes having good strength and hydrolytic stability.

[0005] In a first aspect, the present disclosure provides a cationic copolymer comprising divalent monomer units (hereinafter “monomer units”):

[0006] (a)

[0007] (b)

[0008] (c)

[0009] wherein:

[0010] each Ar 1 independently represents a phenylene group;

[0011] each L independently represents a direct bond or

[0012]

[0013] wherein each R 1 independently represents an alkyl group having 1 to 4 carbon atoms, and each R 2 independently represents an alkylene group having 1 to 6 carbon atoms, and each Z - represents a monovalent non-interfering anion;

[0014] each Ar 2 independently represents an optionally substituted bivalent aryl ring, with the proviso that if L represents a direct bond, then Ar 2 represents an optionally substituted cationic bivalent aryl ring, said cationic bivalent aryl ring bearing Z -

[0015] each R 3 independently represents H or an alkyl group having 1 to 6 carbon atoms; and

[0016] each D independently represents a direct bond or Ar 2 wherein adjacent D and L are not both direct bonds, and wherein if L is a direct bond, then D is Ar 2 .

[0017] The copolymer according to the present disclosure can be combined with a free radical initiator to provide a curable film precursor composition. The curable film precursor composition can be cured to form a film composition.

[0018] As used herein:

[0019] “Aryl ring” refers to a carbocyclic or heterocyclic ring having 4n+2 π electrons in the ring;

[0020] “Direct bond” with respect to an allocatable group means that the group is not present and the two groups to which it is attached are bonded directly to one another (e.g., A-B-C, where B is a direct bond, is equivalent to A-C);

[0021] “Monomeric unit” refers to the largest structural unit contributed to a polymer structure by a single monomer molecule;

[0022] “Non-interfering anion” refers to an anion that can form a stable salt with a cationic polymer;

[0023] “Phenylene” generally refers to a bivalent phenyl ring;

[0024] Ortho-phenylene has the formula:

[0025] Meta-phenylene has the formula: and

[0026] Para-phenylene has the formula:

[0027] The features and advantages of the present disclosure will be further understood upon consideration of the detailed description and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a schematic exploded side view of an exemplary electrochemical device according to the present disclosure. DETAILED DESCRIPTION ​

[0029] The ionomers according to the present disclosure can be prepared from a corresponding precursor copolymer. The precursor copolymer generally comprises monomer units derived from styrene and monomer units derived from a vinylbenzyl halide (i.e., halomethylstyrene), which is typically vinylbenzyl chloride. If desired, other optional monomer units can be included; for example, to modify the ionic conductivity, solubility, mechanical strength, and swelling characteristics. The precursor copolymer is typically a random copolymer and is typically linear.

[0030] In some preferred embodiments, the precursor copolymer is a random copolymer formed from styrene and a vinylbenzyl halide, such as vinylbenzyl chloride. Such precursor copolymers have monomer units derived from styrene as in Formula II-1 (below) and monomer units derived from a vinylbenzyl halide as in Formula II-2A (below), where X is CI, Br, or I (preferably CI), and where -CH2X can be attached to any of the aromatic ring carbons.

[0031]

[0032] The resulting precursor copolymer generally has the following formula III.

[0033]

[0034] In Formula III, the variable n is the mole percent of monomer units derived from styrene in the precursor copolymer, and the variable m is the mole percent of monomer units derived from a vinylbenzyl halide in the precursor copolymer. The monomer units are generally arranged in a random fashion. That is, monomer units of the same type are not all in one block. As used herein, in a polymer formula, an asterisk (*) indicates a connection to another group, such as, for example, an end group and / or an initiator residue.

[0035] In some embodiments of the precursor copolymer, the sum of the variables n and m is equal to 100 mole percent. That is, the precursor copolymer comprises only two types of monomer units as in Formula (III). The sum of n and m is generally at least 80 mole percent, at least 85 mole percent, at least 90 mole percent, at least 95 mole percent, at least 98 mole percent, at least 99 mole percent, at least 99.5 mole percent, at least 99.8 mole percent, or at least 99.9 mole percent, based on the total moles of monomer units in the precursor copolymer.

[0036] The mole percentage of cationic monomer units derived from a vinylbenzyl halide (e.g., monomer units (b) and (c)) in the precursor copolymer is selected to provide a suitable amount of cationic nitrogen-containing groups in the resulting cationic copolymer. For example, cationic nitrogen-containing groups can be introduced into the cationic copolymer by reaction of a nitrogen-containing base (e.g., a tertiary amine, a tertiary vinyl amine, a pyridine, an N-vinylimidazole, an N-alkylimidazole, an N,N-dialkylamino-alkylstyrene, an N,N-dialkylamino-alkylbenzene, and combinations thereof) with the monomer units derived from a vinylbenzyl halide in the precursor copolymer.

[0037] The mole percentage of cationic monomer units derived from a vinylbenzyl halide (e.g., monomer units (b) and (c)) in the precursor copolymer is typically at least 20 mole percent, such as, for example, in the range of 20 mole percent to 50 mole percent, based on the total moles of monomer units in the precursor copolymer, although this is not required. If this amount is greater than 50 mole percent, the final cationic copolymer can be too soluble or swell in water, water-based solutions, or electrolytes, such as within an electrochemical cell. However, if this amount is less than 20 mole percent, the final cationic copolymer can not have sufficient ionic conductivity. The precursor copolymer typically comprises at least 20 mole percent, at least 25 mole percent, at least 30 mole percent, at least 35 mole percent, at least 40 mole percent, and up to 50 mole percent, up to 45 mole percent, or up to 40 mole percent of monomer units derived from a vinylbenzyl halide, based on the total moles of monomer units in the precursor copolymer.

[0038] When intended for use as a membrane in an electrochemical device, the mole percentage of styrene monomer units in the precursor copolymer, and thus also the resulting cationic copolymer, is selected so that the cationic copolymer is insoluble in water or water-based solutions, or any electrolyte solution, such as an electrolyte solution used within an electrochemical device. However, if this amount is too great, there can not be enough monomer units with cationic charges (e.g., monomer units (b) and (c)) to make the cationic copolymer have sufficient ionic conductivity. In some preferred embodiments, the precursor copolymer comprises at least 50 mole percent, such as, for example, 50 mole percent to 80 mole percent of monomer units derived from styrene, based on the total moles of monomer units in the precursor copolymer; however, this is not required. This amount is typically at least 50 mole percent, at least 55 mole percent, at least 60 mole percent, at least 65 mole percent, at least 70 mole percent, and up to 80 mole percent, up to 75 mole percent, up to 70 mole percent, or up to 65 mole percent, based on the total moles of monomer units in the precursor copolymer.

[0039] In some embodiments, the precursor copolymer comprises 20 to 50 mole percent of monomer units derived from a vinylbenzyl halide (e.g., monomer units (b) and (c)) and 50 to 80 mole percent of styrene monomer units (monomer unit (a)), based on the total number of moles of monomer units in the precursor copolymer. For example, the precursor copolymer can comprise 25 to 50 mole percent of monomer units derived from a vinylbenzyl halide and 50 to 75 mole percent of styrene monomer units, 30 to 50 mole percent of monomer units derived from a vinylbenzyl halide and 50 to 70 mole percent of styrene monomer units, 25 to 45 mole percent of monomer units derived from a vinylbenzyl halide and 55 to 75 mole percent of styrene monomer units, 30 to 45 mole percent of monomer units derived from a vinylbenzyl halide and 55 to 70 mole percent of monomer units derived from styrene, or 30 to 40 mole percent of monomer units derived from a vinylbenzyl halide and 60 to 70 mole percent of monomer units derived from styrene.

[0040] The precursor copolymer can be prepared by mixing the monomers with a thermal free radical initiator (hereinafter "thermal initiator"); for example, according to methods known in the art. Exemplary thermal initiators include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2-methylbutyronitrile), and organic peroxides (e.g., benzoyl peroxide and lauroyl peroxide), and mixtures thereof.

[0041] The amount of thermal initiator is typically in the range of 0.01 to 5 weight percent, based on the total weight of monomers included in the precursor reaction mixture. The amount can be at least 0.01 weight percent, at least 0.05 weight percent, at least 0.1 weight percent, at least 0.5 weight percent, at least 1 weight percent, and at most 5 weight percent, at most 4 weight percent, at most 3 weight percent, at most 2 weight percent, or at most 1 weight percent; however, higher amounts can also be used. The amount of thermal initiator can be used to control the molecular weight. That is, an increase in the amount tends to result in the preparation of a lower molecular weight precursor copolymer.

[0042] The polymerization reaction to form the precursor copolymer can be conducted in the reaction mixture in the presence or absence of an organic solvent and / or water. That is, the solids content of the precursor reaction mixture can be up to 100 wt.%. The solids content is equal to the percentage of all components of the precursor reaction mixture that are not organic solvents and / or water. By organic solvent is meant a non-reactive, organic liquid component. An organic solvent can be added to reduce the viscosity of the precursor reaction mixture to allow for proper mixing of the components and to facilitate handling of the final polymer solution. However, if the solids content is too low, then excess organic solvent and / or water needs to be removed. This adds additional cost and time to the preparation of the precursor copolymer. The solids content is typically in the range of 30 wt.% to 100 wt.% based on the total weight of the precursor reaction mixture. For example, the solids content can be at least 30 wt.%, at least 40 wt.%, at least 50 wt.% or at least 60 wt.% and up to 100 wt.%, up to 90 wt.%, up to 80 wt.% or up to 70 wt.%.

[0043] If an organic solvent is added to the precursor reaction mixture, then the organic solvent is typically selected based on its ability to form a single phase with the monomers and with the resulting precursor copolymer. The organic solvent can be, for example, a ketone (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone), an ester such as an alkyl acetate (e.g., ethyl acetate and butyl acetate), or an aromatic hydrocarbon that can optionally be halogenated (e.g., toluene and chlorobenzene).

[0044] The molecular weight (e.g., number average molecular weight Mw n ) of the precursor copolymer is typically in the range of 20,000 Daltons to 100,000 Daltons, but this is not essential. If the weight average molecular weight is lower than 20,000 Daltons, then the cationic copolymer formed from the precursor copolymer can not be robust enough to be used as an anion exchange membrane in an electrochemical cell. On the other hand, if the weight average molecular weight is greater than 100,000 Daltons, then the resulting cationic copolymer solution can have a viscosity that is too high to be easily processed. The weight average molecular weight can be at least 20,000 Daltons, at least 30,000 Daltons, at least 40,000 Daltons or at least 50,000 Daltons and up to 100,000 Daltons, up to 90,000 Daltons, up to 80,000 Daltons, up to 70,000 Daltons or up to 60,000 Daltons. For example, the weight average molecular weight can be in the range of 40,000 Daltons to 100,000 Daltons, in the range of 40,000 Daltons to 80,000 Daltons, in the range of 50,000 Daltons to 80,000 Daltons, in the range of 40,000 Daltons to 70,000 Daltons or in the range of 50,000 Daltons to 70,000 Daltons.

[0045] The cationic copolymer can be formed from a precursor copolymer. More specifically, the precursor copolymer can be reacted with a corresponding nitrogenous base (e.g., tertiary amine, pyridine, N-alkyl imidazole) which can nucleophilically displace the benzyl halide to produce monomer units (b) and (c) as the corresponding halide salt. The halide anion can subsequently be exchanged and replaced with other non-interfering monovalent anions that do not react with the cationic polymer under normal ambient or intended use conditions. Examples can include other halide ions (e.g., CI, Br, I), hydroxide, bicarbonate, methylsulfonate, trifluoroacetate, acetate, and nitrate.

[0046] The nitrogenous base is typically added to the precursor copolymer in the presence of one or more organic solvents. Water can also be present. The solvent system is chosen such that the final product (i.e., the cationic nitrogenous copolymer, which is the cationic copolymer) is dissolved. The solvent system can or can not dissolve the precursor copolymer. That is, the initial reaction mixture can be a solution or a slurry. If the initial reaction mixture is a slurry, the solvent system is typically chosen such that the resulting cationic copolymer is dissolved. Suitable solvents that can dissolve both the precursor copolymer as well as the cationic copolymer include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethylsulfoxide. Suitable solvents that can dissolve the cationic copolymer but not the precursor copolymer include, but are not limited to, methanol, ethanol, 1-methoxy-2-propanol, and blends thereof with toluene. The reaction mixture is typically heated at an elevated temperature for at least 30 minutes, at least 1 hour, or even longer. The solids weight percent is typically in the range of 10 wt% to 60 wt%, 20 wt% to 50 wt%, or 20 wt% to 40 wt%.

[0047] With respect to monomer unit (b), in some preferred embodiments, the corresponding nitrogenous base is represented by the formula (R 1 )2N-R 2 -Ar 2 -CH=CH2. Each R 1 independently represents an alkyl group having 1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, or butyl), preferably methyl. Each R 2 independently represents an alkylene group having 1 to 6 carbon atoms (e.g., methylene, ethylene, 1,3-propanediyl, 1,4-butanediyl, 1,5-pentanediyl, or 1,6-hexanediyl), preferably methylene, ethylene, or 1,3-propanediyl. In these embodiments, each Ar 2 independently represents an optionally substituted, divalent, uncharged aryl ring such as, for example: o-phenylene, m-phenylene, or p-phenylene; imidazol-1,3-diyl; 2,4,5-trimethylimidazol-1,3-diyl; 1,2-dimethylimidazol-1,3-diyl; 2,5-dimethylimidazol-1,3-diyl; or 2,4-dimethylimidazol-1,3-diyl. Typically, Ar2 such that it does not contain or contribute to an N-H bond. One preferred nitrogen-containing base is N,N-dimethylaminomethylstyrene (ortho-, meta-, and para-isomers and combinations thereof).

[0048] In certain preferred embodiments (e.g., embodiments in which L is a direct bond), Ar 2 represents an N-vinylimidazolium group (see Formula IV below), the corresponding nitrogen-containing base is represented by Formula V below.

[0049]

[0050] where R 4 is hydrogen or an alkyl group having 1 to 4 carbon atoms, preferably methyl or ethyl. Examples include 1-vinylimidazole (i.e., N-vinylimidazole); 2,4,5-trimethyl-1- vinylimidazole; 2,5-dimethyl-1-vinylimidazole; and 2,4-dimethyl-1-vinylimidazole. Suitable corresponding N-vinylimidazoles are commercially available or prepared by known methods, for example.

[0051] To provide monomer units (c), the precursor copolymer can be reacted with additional nitrogen-containing bases that lack a vinyl group adjacent to the aryl ring in monomer units (b). For example, in some preferred embodiments, the corresponding tertiary amine is represented by Formula (R 1 )2N-R 2 -Ar 2 -R 3 . Each R 1 independently represents an alkyl group having 1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, or butyl), preferably methyl. Each R 2 independently represents an alkylene group having 1 to 6 carbon atoms (e.g., methylene, ethylene, 1,3- propanediyl, 1,4-butanediyl, 1,5-pentanediyl, or 1,6-hexanediyl), preferably methylene, ethylene, or 1,3- propanediyl. Each Ar 2 independently represents an optionally substituted divalent aryl ring, such as, for example: o-phenylene, m-phenylene, or p-phenylene; imidazole-1,3-diyl; 2,4,5-trimethylimidazole-1,3-diyl; 2,5-dimethylimidazole-1,3-diyl; or 2,4-dimethylimidazole-1,3-diyl. Ar 2 such that it does not contain or contribute to an N-H bond. Each R 3 independently represents H or an alkyl group having 1 to 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl). Typically, R 3 is chosen such that when R 3 is H, it is not bonded to nitrogen.

[0052] In certain preferred embodiments (e.g., some embodiments in which L is a direct bond), suitable tertiary amines are represented by the following Formula VI:

[0053]

[0054] wherein R 3 and R 4 are as previously defined. Examples include 1-methylimidazole (i.e., N-methylimidazole); 1-ethylimidazole; 1-propylimidazole; 1-butylimidazole; 1-hexylimidazole; 2,4,5-trimethyl-l-methylimidazole; 2,5-dimethyl-l-methylimidazole; and 2,4-dimethyl-l-methylimidazole. For example, suitable corresponding imidazoles are commercially available or prepared by known methods.

[0055] when Ar 2 is a divalent optionally substituted pyridinium group, it can be prepared from the corresponding pyridine of the following Formula VII.

[0056]

[0057] wherein R 3 and R 4 are as previously defined. Examples include: pyridine; 2-methylpyridine, 3-methylpyridine, or 4-methylpyridine; 4-butylpyridine; 4-hexylpyridine; 2,4,6-trimethylpyridine; 2,4-dimethyl-pyridine; and 3,5-dimethylpyridine. For example, suitable corresponding pyridines are commercially available or prepared by known methods.

[0058] Other suitable optional nitrogen-containing bases that can be reacted with the precursor copolymer include unsaturated heterocyclic compounds having five-membered rings, such as pyrrole, pyrazole, triazole, and tetrazole; and unsaturated compounds having six-membered rings, such as pyrimidine, pyrazine, pyridazine, and triazine. Saturated nitrogen-containing bases, such as piperidine and piperazine, can also be used. Any of these compounds can be substituted with one or more alkyl groups.

[0059] Other suitable optional nitrogen-containing bases are trialkylamines. The alkyl groups can be linear, branched, or cyclic (depending on the number of carbon atoms) and can independently have from 1 to 10 carbon atoms, preferably from 1 to 4 carbon atoms. Specific examples include, but are not limited to, trimethylamine, triethylamine, ethyldimethylamine, butyldimethylamine, and diisopropylethylamine.

[0060] Other suitable optional nitrogen-containing bases that can react with the precursor copolymer include guanidinium compounds that are substituted with multiple alkyl groups. In some embodiments, the guanidinium group is fully substituted with alkyl groups. Suitable alkyl groups typically contain 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, or 1 to 3 carbon atoms, and the alkyl groups can be linear, branched, or cyclic (depending on the number of carbon atoms). Examples include, but are not limited to, pentamethylguanidine, 2-tert-butyl-l, 1,2,2-tetramethylguanidine, and N,N-diethyl-N,N',N'-trimethylguanidine, as well as cyclic and polycyclic compounds such as 2-methylimino-l,3-dimethylimidazolidine and 7-methyl-l,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0061] Various nitrogen-containing bases are used to introduce side nitrogen-containing groups and form monomer units (b) and (c) in the cationic copolymer. More specifically, the nitrogen-containing base reacts with the monomer units in the precursor copolymer that are derived from the vinylbenzyl halide. While reacting all available monomer units with the nitrogen-containing base can increase the overall ionic conductivity, adding more positively charged groups to the cationic copolymer tends to increase its swelling and solubility in water or water-based solutions, such as those used in various electrolytes within electrochemical cells. While increased ionic conductivity is desirable for use in electrochemical cells, increased swelling and solubility tends to be undesirable. The mole percentage of monomer units derived from the reacted vinylbenzyl halide is typically a tradeoff between ionic conductivity on one hand and swelling and solubility on the other. Typically, the total moles of nitrogen-containing base are selected to react with at least 60 mole percent, at least 65 mole percent, at least 70 mole percent, at least 75 mole percent, at least 80 mole percent, at least 85 mole percent, and up to 100 mole percent, up to 99 mole percent, up to 97 mole percent, up to 95 mole percent, up to 90 mole percent, up to 85 mole percent, or up to 80 mole percent of the monomer units derived from the vinylbenzyl chloride. Typically, the total moles of nitrogen-containing base are selected to be less than the moles of monomer units derived from the vinylbenzyl halide to avoid the presence of excess nitrogen-containing base in the final product solution.

[0062] When preparing for use in an electrochemical cell, the cationic copolymer typically comprises 20 to 50 mole percent of nitrogen-containing monomeric units, based on the total moles of monomeric units in the cationic copolymer. These nitrogen-containing monomeric units are typically cationic. If a lower amount of nitrogen-containing monomeric units is present (i.e., less than 20 mole percent, based on the total moles of monomeric units), the resulting cationic copolymer can not have sufficient ionic conductivity. However, if a higher amount of nitrogen-containing monomeric units is present, the resulting cationic copolymer can be too soluble and / or swell too much when used as an anion exchange membrane in an electrochemical cell. The cationic copolymer can comprise at least 20 mole percent, at least 25 mole percent, at least 30 mole percent, at least 35 mole percent, or at least 40 mole percent, and up to 50 mole percent, up to 45 mole percent, up to 40 mole percent, up to 35 mole percent, or up to 30 mole percent of cationic nitrogen-containing monomeric units. In many embodiments, all of the nitrogen-containing monomeric units are monomeric units (b) or (c).

[0063] Monomeric units (c) can comprise, on a molar basis, and in any combination, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 40%, or at least 50%, and up to 100%, up to 95%, up to 90%, up to 80%, up to 70%, up to 60%, up to 50%, up to 40%, up to 30%, or up to 20% of all cationic nitrogen-containing monomeric units in the cationic copolymer. In some embodiments, monomeric units (c) can comprise, on a molar basis, 10% to 95%, 20% to 95%, 30% to 95%, 40% to 95%, 10% to 90%, or 10% to 80%, 20% to 80%, 30% to 80%, 40% to 80%, or 40% to 60% of all cationic nitrogen-containing monomeric units in the cationic copolymer.

[0064] In particular, when preparing a cationic copolymer for use in an electrochemical cell, the total amount of cationic nitrogen-containing monomeric units is in the range of 20 to 50 mole percent, and the cationic nitrogen-containing monomeric units correspond to monomeric units (b) and / or (c). The total amount of cationic nitrogen-containing monomeric units can be at least 20 mole percent, at least 25 mole percent, at least 30 mole percent, or at least 35 mole percent, and up to 50 mole percent, up to 45 mole percent, up to 40 mole percent, up to 35 mole percent, or up to 30 mole percent. This mole percent amount is based on the total moles of monomeric units in the cationic copolymer.

[0065] The cationic polymers according to the present disclosure comprise polymerizable vinyl groups, which can be polymerized by free radical polymerization and which can be cured (i.e., crosslinked), for example, to form a membrane.

[0066] Accordingly, the present disclosure also provides a curable film precursor composition comprising the cationic copolymer according to the present disclosure and a free radical initiator. Useful free radical initiators can include thermal initiators and / or photoinitiators. For rapid curing in a continuous manufacturing process, photoinitiators are generally preferred. In some cases, electron beam radiation can be used to effect curing / crosslinking.

[0067] Exemplary useful thermal initiators include azo compounds such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2-methylbutyronitrile) and organic peroxides (e.g., benzoyl peroxide and lauroyl peroxide) and mixtures thereof.

[0068] Exemplary useful photoinitiators include benzoin and its derivatives such as a-methylbenzoin; a-phenylbenzoin; a-allylbenzoin; a-benzylbenzoin; benzoin ethers such as benzoin dimethyl ketal, benzoin methyl ether, benzoin ethyl ether, benzoin n-butyl ether; acetophenone and its derivatives such as 2-hydroxy-2-methyl-l-phenyl-l- propanone and l-hydroxycyclohexyl phenyl ketone; 2-methyl-l-[4-(methylthio)phenyl]-2-(4- morpholinyl)-l-propanone; 2-benzyl-2-(dimethylamino)-l-[4-(4-morpholinyl)phenyl]-l-butanone. Other useful photoinitiators include, for example, pivaloyl ethyl ether, anisoin ethyl ether, anthraquinones (e.g., anthraquinone, 2-ethylanthraquinone, 1-chloroanthraquinone, 1,4-dimethylanthraquinone, 1-methoxyanthraquinone, or benzoanthraquinone), halomethyltriazines, benzophenone and its derivatives, iodonium and sulfonium salts, titanium complexes such as bis(eta5-2,4-cyclopentadien-l-yl)-bis[2,6-difluoro-3-(lH-pyrrol-l-yl)phenyl]titanium; halonitrobenzenes (e.g., 4-bromomethyl nitrobenzene), mono- and bis-acyl phosphines, and mono- and bis-acyl phosphinic acid esters (e.g., (2,4,6-trimethylbenzoyl)phenyl phosphinic acid ethyl ester). Combinations of photoinitiators can be used. One or more spectral sensitizers (e.g., dyes) can be used with the photoinitiator, for example, in order to increase the sensitivity of the photoinitiator to a particular source of actinic radiation.

[0069] The amount of free radical initiator is generally in the range of 0.01 to 5 weight percent, based on the total weight of the film precursor composition. The amount can be at least 0.01 weight percent, at least 0.05 weight percent, at least 0.1 weight percent, at least 0.5 weight percent, at least 1 weight percent, and at most 5 weight percent, at most 4 weight percent, at most 3 weight percent, at most 2 weight percent, or at most 1 weight percent; however, higher amounts can also be used.

[0070] Sources of actinic radiation that can be used include lasers, arc lamps (e.g., medium pressure mercury arc lamps), xenon flash lamps, microwave driven lamps (e.g., equipped with H-bulbs or D-bulbs). Selection of suitable exposure conditions will be within the ability of one of skill in the art.

[0071] The membranes made from the membrane composition can have any suitable thickness, preferably 10 micrometers to 200 micrometers. For example, the thickness can be at least 10 micrometers, at least 20 micrometers, at least 30 micrometers, at least 40 micrometers, or at least 50 micrometers, and / or up to 200 micrometers or more, up to 150 micrometers, up to 100 micrometers, or up to 50 micrometers.

[0072] In some embodiments, the anion exchange membrane can further include a reinforcing material, such as a porous support. The porous support can be a woven or nonwoven material made from polymeric materials such as, for example, fluoropolymers (e.g., polytetrafluoroethylene) or polyolefins (e.g., polyethylene or polypropylene), electrospun fibers, glass fibers, polymeric fibers, fibrous mats, perforated membranes, and porous ceramics. The reinforcing material can be absorbed (e.g., saturated or coated) with a liquid composition containing the cationic copolymer described herein neat or containing a solvent (dissolved in a suitable solvent) and then the solvent (if present) is removed to embed the cationic copolymer in the pores of the reinforcing material. The porous support is typically non-conductive and ionically non-conductive.

[0073] The membranes according to the present disclosure can be used in various electronic devices. In some embodiments, the electronic device is an electrolytic cell.

[0074] Examples of electrochemical devices include, but are not limited to, fuel cells, electrolytic cells, batteries, or electrodialysis cells.

[0075] The electrode material can include, for example, graphite carbon, glassy carbon, titanium, or any of the following “catalytically active elements”: V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Ir, Pt, Au, Hg, Al, Si, In, Tl, Pb, Bi, Sb, Te, U, Sm, Tb, La, Ce, Nd, and alloys or combinations thereof.

[0076] In one embodiment, the cathode of the electrochemical device includes a catalytically active material that includes silver, gold, copper, nickel, iron, or combinations thereof.

[0077] In one embodiment, the anode of the electrochemical device includes a catalytically active material that includes ruthenium, iridium, platinum, titanium, nickel, iron, cobalt, or combinations thereof.

[0078] In one embodiment, the electrochemical device is substantially platinum-free, which means that, based on the total weight of the electrodes, the electrodes contain less than 0.1 wt%, less than 0.01 wt%, or even less than 0.001 wt% of platinum.

[0079] The cathode, anode, and membrane can be assembled as separate components, or combined with one or two electrodes or portions thereof during the manufacture of electronic devices. For example, to maximize cost savings and, in some cases, performance, the components or their layers can be thin enough that some of these components can act as supports during thin-layer fabrication. Various components or portions thereof can be laminated together, formed in situ on the surface of the components, and / or coated onto the components.

[0080] The assembly, which includes an anode, a cathode, and an anion exchange membrane, can be sandwiched between two flow field plates and then held together such that each layer is in contact with the adjacent layer, preferably in close contact.

[0081] Figure 1 An exemplary electrochemical device—an electrolyzer—is illustrated. The electrolyzer 30 includes a membrane electrode assembly 32, typically formed of graphite or a graphite composite, interposed between rigid flow field plates 34 and 36. The membrane electrode assembly 32 consists of an anion exchange membrane 42 interposed between two electrodes, namely an anode 44 and a cathode 46. The anode 44 and cathode 46 are typically formed of a porous conductive sheet material such as carbon fiber paper and have planar main surfaces. Electrodes 44 and 46 have a thin layer of catalyst material disposed on their main surfaces at their interfaces with the membrane 42 to make them electrochemically active. Figure 1 As shown, the anode flow field plate 34 has at least one open surface channel 34a etched, milled, or molded in its main surface facing the film 42. Similarly, the cathode flow field plate 36 has at least one open surface channel 36a etched, milled, or molded in its main surface facing the film 42. When assembled against the cooperating surfaces of electrodes 44 and 46, channels 34a and 36a respectively form reactive stream channels for the anolyte reactive stream (if any) and the cathode reactive stream.

[0082] Selected embodiments of the present disclosure

[0083] In a first embodiment, this disclosure provides a cationic copolymer comprising divalent monomer units:

[0084] (a)

[0085] (b)

[0086] (c)

[0087] in:

[0088] each Ar 1 independently represents a phenylene group;

[0089] each L independently represents a direct bond or

[0090]

[0091] wherein each R 1 independently represents an alkyl group having 1 to 4 carbon atoms, and each R 2 independently represents an alkylene group having 1 to 6 carbon atoms, and each Z - represents a non-interfering monovalent anion;

[0092] each Ar 2 independently represents an optionally substituted bivalent aromatic ring, with the proviso that if L represents a direct bond, then Ar 2 represents an optionally substituted cationic bivalent aromatic ring, said cationic bivalent aromatic ring bearing Z - ;

[0093] each R 3 independently represents H or an alkyl group having 1 to 6 carbon atoms; and

[0094] each D independently represents a direct bond or Ar 2 , wherein adjacent D and L are not both direct bonds, and wherein if L is a direct bond, then D is Ar 2 .

[0095] In a second embodiment, the present disclosure provides the cationic copolymer according to the first embodiment, wherein the ratio of the number of moles of monomer units a) to the sum of the number of moles of monomer units b) and c) is 1 : 1 to 4: 1.

[0096] In a third embodiment, the present disclosure provides the cationic copolymer according to the first or second embodiment, wherein for at least some monomer units b), at least some Ar 1 is a p-phenylene group.

[0097] In a fourth embodiment, the present disclosure provides the cationic copolymer according to any one of the first to third embodiments, wherein for at least some monomer units b), L is a direct bond, and Ar 2 is represented by the following formula:

[0098]

[0099] wherein each R 4 independently represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and each Z -independently represents a non-interfering anion.

[0100] In a fifth embodiment, the present disclosure provides a cationic copolymer according to any one of the first to fourth embodiments, wherein for at least some monomer units b), each L independently represents:

[0101]

[0102] In a sixth embodiment, the present disclosure provides a cationic copolymer according to the fifth embodiment, wherein each R 1 is methyl, R 2 is methylene, and Ar 2 is phenylene.

[0103] In a seventh embodiment, the present disclosure provides a cationic copolymer according to the sixth embodiment, wherein Ar 2 is p-phenylene.

[0104] In an eighth embodiment, the present disclosure provides a curable film precursor composition comprising:

[0105] i) a cationic copolymer according to any one of the first to third embodiments; and

[0106] ii) a free radical initiator.

[0107] In a ninth embodiment, the present disclosure provides a curable film precursor composition comprising:

[0108] i) a cationic copolymer according to the fourth embodiment; and

[0109] ii) a free radical initiator.

[0110] In a tenth embodiment, the present disclosure provides a curable film precursor composition comprising:

[0111] i) a cationic copolymer according to the fifth or sixth embodiment; and

[0112] ii) a free radical initiator.

[0113] In an eleventh embodiment, the present disclosure provides a film composition comprising at least partially cured curable film composition according to the eighth to tenth embodiments.

[0114] In a twelfth embodiment, the present disclosure provides an electrochemical device comprising:

[0115] an anode;

[0116] a cathode; and

[0117] a membrane positioned between the anode and the cathode, wherein the membrane comprises the membrane composition according to the eleventh embodiment.

[0118] The objects and advantages of the present disclosure are further illustrated by, but not by way of limiting to, the following non-limiting examples, in which the particular materials recited in the examples and amounts thereof and other conditions and details are not to be construed as undue limitations.

[0119] Examples

[0120] All parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight, unless otherwise indicated. Table 1 below lists the materials and abbreviations used in the Examples.

[0121] Table 1

[0122]

[0123]

[0124] Example 1

[0125] Preparation of Polymer 1

[0126] A 1 liter glass amber bottle was charged with 170 g of styrene, 141.2 g of VBC, 244.4 g of chlorobenzene, and 2.92 g of AIBN. The mixture was shaken to dissolve the AIBN and then bubbled with nitrogen for 4 minutes at room temperature. The glass bottle was then sealed and placed in a stirred water bath at 60 °C for 48 hours. The resulting viscous polymer solution (450.2 g) was poured into 2500 ml of methanol under mechanical stirring to precipitate the polymer solids. The solids were washed with methanol a total of four times and then dried at room temperature under a gentle stream of nitrogen. This resulted in 235 g of solids.1H NMR analysis showed a molar ratio of styrene / VBC monomer units of 64.1 / 35.9 and a total residual monomer content of 0.5 mol%. 1 H NMR analysis showed a molar ratio of styrene / VBC monomer units of 64.1 / 35.9 and a total residual monomer content of 0.5 mol%.

[0127] A 250 mL three necked round bottom flask, equipped with magnetic stirring and oil bath heating, was charged with 25.0 g of the above copolymer, 8.02 g of TMIm (TMIm / VBC molar ratio = 0.874) and 68.16 g of methoxypropanol. The mixture was stirred at 75 °C for 3 hours, then 0.55 g of DMAMS (DMAMS / VBC ratio = 0.046) was added by pipette. The mixture was stirred at 75 °C for an additional 5 hours. The clear reaction mixture was allowed to cool, then the ionomer was isolated by pouring about 15-20 ml of the product solution into 500 ml of ethyl acetate in a 1 liter conical flask, equipped with magnetic stirring. The mixture was stirred at room temperature overnight, then the solids were allowed to settle, and the solvent was decanted. The ionomer was washed twice more with ethyl acetate, then isolated and dried at room temperature under a stream of nitrogen. The resulting powder was analyzed by1H NMR in d3-acetonitrile solution and showed a composition with 63.4 / 29.3 / 1.5 / 5.8 molar ratio of styrene / VBTMImCl / VBDMAMSCl / VBC monomer units, respectively, where VBTMImCl refers to the quaternary ammonium salt adduct of VBC monomer units and TMIm (vinylbenzyl tetramethylimidazolium chloride), and VBDMAMS refers to the quaternary ammonium salt adduct of VBC monomer units and DMAMS. The product was diluted to 33 wt% in methoxypropanol to give a clear, viscous solution. 1 H NMR in d3-acetonitrile solution and showed a composition with 63.4 / 29.3 / 1.5 / 5.8 molar ratio of styrene / VBTMImCl / VBDMAMSCl / VBC monomer units, respectively, where VBTMImCl refers to the quaternary ammonium salt adduct of VBC monomer units and TMIm (vinylbenzyl tetramethylimidazolium chloride), and VBDMAMS refers to the quaternary ammonium salt adduct of VBC monomer units and DMAMS. The product was diluted to 33 wt% in methoxypropanol to give a clear, viscous solution.

[0128] Example 2

[0129] Preparation of Polymer 2

[0130] A 250 mL three necked round bottom flask, equipped with magnetic stirring and oil bath heating, was charged with 25.0 g of the above copolymer, 8.02 g of TMIm (TMIm / VBC molar ratio = 0.874) and 68.16 g of methoxypropanol. The mixture was stirred at 75 °C for 3 hours, then 0.55 g of DMAMS (DMAMS / VBC ratio = 0.046) was added by pipette. The mixture was stirred at 75 °C for an additional 5 hours. The clear reaction mixture was allowed to cool, then the ionomer was isolated by pouring about 15-20 ml of the product solution into 500 ml of ethyl acetate in a 1 liter conical flask, equipped with magnetic stirring. The mixture was stirred at room temperature overnight, then the solids were allowed to settle, and the solvent was decanted. The ionomer was washed twice more with ethyl acetate, then isolated and dried at room temperature under a stream of nitrogen. The resulting powder was analyzed by1H NMR in d3-acetonitrile solution and showed a composition with 63.4 / 29.3 / 1.5 / 5.8 molar ratio of styrene / VBTMImCl / VBDMAMSCl / VBC monomer units, respectively, where VBTMImCl refers to the quaternary ammonium salt adduct of VBC monomer units and TMIm (vinylbenzyl tetramethylimidazolium chloride), and VBDMAMS refers to the quaternary ammonium salt adduct of VBC monomer units and DMAMS. The product was diluted to 33 wt% in methoxypropanol to give a clear, viscous solution. 1HNMR analysis showed a 88:12 (molar) monomeric unit ratio of VBTMImCl and unreacted VBC, and about 2 mol% unreacted tetramethylimidazole. This mixture (42.01 g), 29.14 g of styrene, 45.9 g of MP, and 0.59 g of AIBN were charged into an 8 oz amber glass screw-top bottle. After capping and shaking to dissolve the reagents and leave a clear, homogeneous solution, the mixture was sparged with nitrogen for 2 minutes at room temperature, then capped and sealed and placed in a forced air oven at 60 °C on rollers at 20 rpm for 72 hours. This resulted in a clear, viscous polymer solution. The solution was added to ethyl acetate to precipitate the ionomer as a solid, which was isolated, washed with ethyl acetate a total of two times, and dried at room temperature under a stream of nitrogen. The precipitated and washed ionomer was analyzed by H NMR in d3-acetone 1 HNMR analysis gave a composition of 71.0 / 24.8 / 4.2 molar ratio of styrene / VBTMImCl / VBC, respectively.

[0131] A 22.75 g portion of the above polymer solution was mixed with 9.75 g of MP and 0.51 g of DMAMS in a 40 ml glass screw-top vial. The vial was heated in a forced air oven at 60 °C for 16 hours, then cooled. NMR analysis (d3-acetone solution) of a small sample of the ionomer powder isolated by precipitation and washing in ethyl acetate using the procedure described above showed that most of the residual VBC monomeric units in the starting polymer had reacted with DMAMS. The molar composition of the DMAMS-modified ionomer was estimated to be 70.6 / 26.5 / 2.34 / 0.5 molar ratio of styrene / VBTMImCl / VBDMAMSCl / VBC, respectively, with the benzylated DMAMS units representing 8.1 mole percent of the total cationic units in the ionomer. A portion of the precipitated and washed DMAMS-modified ionomer was diluted with MP to 35 weight percent solids, resulting in a solution that was roller mixed overnight at room temperature for use in coating experiments.

[0132] Example 3

[0133] Preparation of Polymer 3

[0134] A sample of a styrene / vinylbenzyl chloride (S / VBC) copolymer was prepared according to the procedure given above, using a 64 / 36 molar mixture of styrene with 0.94 weight percent AIBN in chlorobenzene, purged with nitrogen, and heated with stirring at 60 °C for 24 hours. The viscous product solution was allowed to cool to room temperature, then slowly added to an excess of methanol with vigorous stirring to precipitate the polymer. The recovered solid was washed with fresh methanol and oven dried to give a white powder. NMR analysis in deuterated chloroform showed a composition of 71.0 / 24.8 / 4.2 molar ratio of styrene / VBTMImCl / VBC, respectively. 1HNMR analysis showed a S / VBC molar ratio of 61.6 / 38.4 with a residual monomer content (S+VBC) of 1.7 mol%.

[0135] A 3-necked round bottom 250 ml flask, equipped with oil bath heating and magnetic stirring, was charged with 100 g MP, 11.43 g (92 mmol) TMIM, 0.6 g potassium iodide (added as an alkylation catalyst) and 0.96 g (10.2 mmol) N-vinylimidazole. The mixture was stirred in an oil bath at 75 °C until all solids were dissolved, then 36.7 g of the S / VBC copolymer prepared above was added as a powder. Stirring and heating were continued. After 30 minutes the swollen polymer spheres had broken up and dissolved, leaving a hazy solution. Stirring and heating were continued for about 27 hours, at which point the flask was removed from the oil bath and allowed to cool. The reaction mixture was a clear, flowable, light yellow liquid with a solids content of 33 wt.%. A few drops of an aliquot were removed by glass pipette and transferred to a small glass vial, which was placed in a vacuum desiccator overnight at room temperature to remove solvent. This left a clear, glassy residue which was dissolved in d6-DMSO for analysis by proton NMR. The resulting spectrum showed that 75 mol% of the chloromethyl groups in the starting copolymer had been converted to imidazolium chloride units, and that the N-vinylimidazolium represented 8.0 mol% of the total imidazolium content.

[0136] Example 4

[0137] Thermal crosslinking of Polymer 3

[0138] A glass screw cap vial was charged with 5 g of a solution of Polymer 3 and 0.79 g of 4.5 wt.% AIBN in MP solution. This corresponds to 2.2 wt.% AIBN based on the ionomer solids. A control vial was also prepared containing 5 g of a solution of Polymer 3 and no AIBN. The vials were connected together using a cable tie and suspended in an oil bath at 75 °C. The samples were checked after 90 minutes and it was found that the sample containing AIBN had gelled while the control was still fluid and had not experienced a significant change in viscosity.

[0139] Examples 5-7

[0140] Films were prepared using a BYK BYKO-Drive Automatic Coater to coat 30-35 wt% of the solid crosslinkable copolymer solutions prepared in Examples 5-7 on release liners having polyethylene terephthalate backing coated with an acrylic release layer as described in U.S. Patent 7,816,477 (Suwa et al.). The BYKO-Drive Automatic Coater (BYK-Gardner GmbH, Geretsried, Germany) was set at a speed of 1 inch / second (2.54 cm / sec) and the film was coated with a notch bar coater having a 10 mil (0.01 inch, 0.254 mm) gap and then dried in a forced air oven at 80 °C for 30 minutes. The measured dry coating thickness was in the range of 45-52 micrometers.

[0141] Examples 8 and 9

[0142] UV crosslinking of the film

[0143] The solution of the curable film composition was modified by adding 1 wt% (based on polymer solids) of TPO-L photoinitiator with stirring to solubilize the initiator. The film was then prepared as described above. After the drying step, the film was passed through a Light Hammer (LHC10 Mark 2) UV processor (Fusion UV Systems Inc., Gaithersburg, Maryland) using a "D bulb" where the conveyor belt was run three times at a speed of 50 feet / minute (15 meters / minute) under a nitrogen atmosphere (total UV dose was approximately 3 J / cm 2 )2. After curing, a clear solid coating was obtained. The results are reported in Table 2 below.

[0144] Example 10

[0145] Thermal crosslinking of the film

[0146] The solution of the curable film composition was modified by adding 2 wt% (based on polymer solids) of AIBN with stirring to solubilize. The film was then prepared as described above. After curing, a clear solid coating was obtained. The results are reported in Table 2 below.

[0147] Table 2

[0148]

[0149] Tensile properties of the film

[0150] Tensile stress-strain properties of the films were examined at a constant strain rate of 2 mm / sec. Samples were soaked in 1 M aqueous KOH for 24 hours at room temperature, washed thoroughly with deionized water, cut into 1.00 cm x 4.00 cm strips, and tested in the fully hydrated state using a TA.XTPlus texture analyzer (Texture Technologies, Hamilton, Massachusetts). Size swelling values were obtained by measuring the x / y / z dimensions of the films before and after aqueous KOH soaking and calculating the percent change. Results are reported in Table 3 below.

[0151] Table 3

[0152]

[0153]

[0154] Successful crosslinking was evidenced by improvements in mechanical properties relative to non-crosslinked analogs (see Table 3). An increase in the stress at break value was demonstrated for UV-cured films (Examples 8 and 9) compared to analogous films that were not exposed to UV light (Examples 5 and 6), and for heat-cured films (Example 10) compared to analogous films that were not exposed to heat curing conditions (Example 7).

[0155] Ion conductivity of the film

[0156] Ionic conductivity was measured using a 4-probe BekkTech BT-110 conductivity jig (Scribner Associates, Inc., Southern Pines, North Carolina) and a VMP3 multichannel potentiostat (Bio-Logic Science Instruments, Seyssinet-Pariset, France). Dry film samples (1.40 cm x 4.00 cm) in chloride form were assembled under two platinum wires, and the jig was immersed in 18 mega-ohm deionized water for 2 hours to hydrate and swell the film prior to measurement. Current-voltage curves were recorded by applying linear voltage sweeps from open circuit voltage (OCV) first to 0.3 V, then to -0.3 V, and finally back to OCV at a scan rate of 10 mV / sec. Ionic conductivity was calculated from the slope of the resulting current-voltage curve using the measured dry film dimensions and thickness and an ion conductivity jig constant of 0.425 cm. Results are reported in Table 4 below.

[0157] Table 4

[0158] Film CL - Ionic conductivity in the form of a gel, (mS / cm) Example 5 20.9 Example 8 20.3 Example 6 19.5 Example 9 10.0 Example 7 Example 10 20.9

[0159] The results in Table 4 show that the UV-crosslinked films of Examples 8 and 9 maintain conductivity compared to similar non-crosslinked films of Examples 5-7.

[0160] The foregoing description shall not be construed to limit the scope of the present disclosure, which is defined by the claims and all equivalents thereof, to practice the present disclosure as claimed by those ordinarily skilled in the art.

Claims

1. A cationic copolymer, said cationic copolymer comprising divalent monomer units: (a) (b) and (c) in: each Ar 1 independently represents a phenylene group; Each L independently represents a direct key or wherein each R 1 independently represents an alkyl group having 1 to 4 carbon atoms, and each R 2 independently represents an alkylene group having 1 to 6 carbon atoms, and each Z - represents a non-interfering monovalent anion; Each Ar 2 Independently representing an optionally substituted divalent aryl ring, provided that if L represents a direct bond, then Ar 2 This represents an optionally substituted cationic divalent aryl ring, said cationic divalent aryl ring being attached with Z - ; Each R 3 Independently representing H or an alkyl group having 1 to 6 carbon atoms; and Each D independently represents a direct bond or Ar. 2 Where adjacent D and L are not both direct bonds, and where if L is a direct bond, then D is Ar. 2 ; and The ratio of the number of moles of monomer unit a) to the sum of the number of moles of monomer units b) and c) is 1:1 to 4:

1.

2. The cationic copolymer according to claim 1, wherein for at least some monomer units b), at least some Ar 1 It is a p-phenylene group.

3. The cationic copolymer according to claim 1, wherein for at least some monomer units b), L is a direct bond and Ar 2 It can be expressed by the following formula: Each R 4 Independently representing hydrogen or an alkyl group having 1 to 4 carbon atoms, and each Z - Independently represents non-interfering anions.

4. The cationic copolymer according to claim 1, wherein for at least some monomer units b), each L independently represents 5. The cationic copolymer according to claim 4, wherein each R 1 It is methyl, R 2 It is a subunit of α, and Ar 2 It is a phenylene group.

6. The cationic copolymer according to claim 5, wherein Ar 2 It is a p-phenylene group.

7. A curable film precursor composition, said curable film precursor composition comprising: i) the cationic copolymer according to claim 1; and ii) Free radical initiators.

8. A curable film precursor composition, said curable film precursor composition comprising: i) the cationic copolymer according to claim 3; and ii) Free radical initiators.

9. A curable film precursor composition, said curable film precursor composition comprising: i) the cationic copolymer according to claim 4; and ii) Free radical initiators.

10. A membrane composition comprising at least partially cured curable membrane composition according to claim 7.

11. A membrane composition comprising at least partially cured curable membrane composition according to claim 8.

12. A membrane composition comprising at least partially cured curable membrane composition according to claim 9.

13. An electrochemical device, said electrochemical device comprising: anode; cathode; as well as A membrane located between the anode and the cathode, wherein the membrane comprises a membrane composition according to any one of claims 10 to 12.

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