Organic superacids, polymers, derived from organic superacids, and methods of making and using the same
View Patent ↗One embodiment of the invention contemplates a proton exchange membrane for use in a variety of fuel cells. The proton exchange membrane may comprise a solid phase organic based copolymer material in which a first structural unit is derived from a polymerizable organic super acid. The organic super acid may comprise an acid group such as a sulfonic acid group or a carboxylic acid group.
1. A method comprising:
providing a polymerizable organic superdiacid monomer that has the general formula
and wherein
A comprises a sulfonic acid group, a carboxylic acid group, or a phosphoric acid group, Y′ is O, S, or a direct carbon bond, each individual B comprises any of an alcohol, a halide, NO 2 , a low molar volume ether group, a low molar volume ester group, or a low molar volume carbonate group with the proviso that at least two are alcohols, and Z is a sulfonyl group or a carbonyl group; and
polymerizing the polymerizable organic superdiacid monomer by way of a polycondensation reaction.
2. The method of claim 1 wherein polymerizing the polymerizable organic superdiacid monomer comprises polymerizing, by way of a polycondensation reaction, the polymerizable organic superdiacid monomer with an aromatic monomer that has the general formula
and wherein
Y comprises an electron withdrawing group; and
X comprises a leaving group.
3. The method of claim 2 wherein Y comprises —O—, —S—, —CO—, —SO 2 —, —P(O)R—, an alkyl group, a perfluoroalkyl group, or a heteroaromatic ring, wherein R is a hydrocarbon group.
4. The method of claim 3 wherein the heteroaromatic ring comprises pyridine, oxazole, benzoxazole, quinoxaline, or oxadiazole.
5. The method of claim 2 wherein X comprises F, Cl, Br, or NO 2 , OH, or SH.
6. The method of claim 5 wherein X is OH or SH if any B of the polymerizable organic superdiacid monomer is a halide.
7. The method of claim 2 wherein the aromatic monomer comprises one of 4,4′-difluorobenzophenone, 4,4′-difluorodiphenylsulfone, 4,4′-didichlorodiphenylsulfone, or 1,3-bis(4′-fluorobenzoyl)benzene.
8. The method of claim 1 wherein polymerizing the polymerizable organic superdiacid monomer comprises polymerizing the polymerizable organic superdiacid in a solvent and a base.
9. The method of claim 8 wherein the solvent is comprises sulfolane, diphenylsulfone, dimethylfluoride, dimethylsulfoxide, dimethylacetamide, N-methylpyrrolidinone, or combinations thereof.
10. The method of claim 8 wherein the base comprises sodium hydroxide, potassium carbonate, or a combination thereof.