| abstract |
A multilayer electrolyte membrane for polymer electrolyte fuel cells, consisting of a laminate of at least two polymer electrolyte membranes at least one of which membranes comprises a block copolymer (I) which comprises, as its constituents, a polymer block (A) having as a main unit an aromatic vinyl compound unit and a flexible polymer block (B), and has ion-conducting groups on polymer block (A); and a membrane electrode assembly and a polymer electrolyte fuel cell. The multilayer membrane is economical, mild to the environment, and has high ion conductivity and high methanol barrier properties, together. It is preferred, from the object, that at least two of the constitutive electrolyte membranes comprise block copolymer (I), and/or at least one of the constitutive electrolyte membranes has an ion exchange capacity of 0.7 meq/g or more and at least one of them has an ion exchange capacity of less than 0.7 meq/g. |