Crosslinked ion conductive membranes
Assignee3M Innovative Properties Company
InventorsShane S. Mao, Steven J. Hamrock, David A. Ylitalo
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Abstract
A method is provided for making crosslinked acidic polymers useful as ion conductive membranes, such as crosslinked sulfonated polyether ketones, sulfonated polysulfones, sulfonated polystyrenes, and other acidic polymers, by crosslinking with a species which generates an acidic functionality. The crosslinker preferably binds to acid functions by conversion of acid groups to imide functionality, which, due to the acidity of the N-H bonds therein, compensate for the acidity lost by the occupation of the acid groups and thus preserve membrane conductivity while contributing to membrane strength and resistance to swelling.
Claims26
A method of making a crosslinked polymer comprising the step selected from steps i) and ii):
- i) crosslinking a polymer having pendant acid halide groups by reaction with a crosslinker which bonds to one or more acid halide groups to contribute one or more groups having pKa<5,
- ii) crosslinking a polymer having pendant amide groups, with a crosslinker which bonds to one or more amide groups to contribute one or more groups having pKa<5.
The method according to claim I wherein said crosslinker binds to said polymer having pendant groups to form an imide group of the formula:
- --AO.sub.n --N.sup.- [M.sup.+ ]--AO.sub.n --
- wherein each A is independently chosen from the group consisting of C, S and P, wherein, for each AO.sub.n, n=1 when A is C and n=2 when A is S or P;
- and wherein M.sup.+ is any cationic species including H.sup.+.
A method of making a crosslinked polymer comprising the step of crosslinking a polymer having pendant groups of the formula --AO.sub.n G by reaction with a crosslinker of the formula(JAO.sub.n).sub.m Z, where either G is a halide and J is --NH.sub.2 or G is --NH.sub.2 and J is a halide, where each A is independently C, S or P, where, for each AO.sub.n, n=1 when A is C and n=2 when A is S or P, where m>1, and where Z is a polyvalent linker which may be a polymer, a substituted or unsubstituted alkyl, a substituted or unsubstituted aryl or a substituted or unsubstituted heteroatomic function.
A crosslinked polymer having crosslinks of the formula:
- [polymer backbone]--SO.sub.2 N.sup.- [M.sup.+ ]SO.sub.2 --[polymer backbone ]
- wherein M.sup.+ is any cationic species including H.sup.+.
A method of making a crosslinked polymer that comprises an imide group of formula I:
- --AO.sub.n --N.sup.- [M.sup.+ ]--AO.sub.n -- (I)
- wherein each A is independently chosen from the group consisting of C, S and P, wherein, for each AO.sub.n, n=1 when A is C and n=2 when A is S or P;
- and wherein M.sup.+ is any cationic species including H.sup.+, from a polymer that does not comprise an imide group of formula I above.
Dependencies are inferred from the claim text.