| abstract |
A polymer electrolyte membrane comprising as a main ingredient a block copolymer (P) which comprises, as its constituents, a vinyl alcoholic polymer block (A) and a polymer block (B) having ion-conducting groups, which block copolymer (P) is cross-linking treated, and a membrane-electrode assembly and a fuel cell using the polymer electrolyte membrane, respectively. Preferred as polymer block (B) is one having a styrene or vinylnaphthalene skeleton or a 2-(meth)acrylamido-2-methylpropane skeleton. The ion-conducting group includes a sulfonic acid group, a phosphonic acid group or the like. |