Patent ID: 7022428

Claim:
A membrane electrode assembly comprising an anode and a cathode sandwiching a membrane comprising a fluorinated ionomer comprising at least (a) a substantially fluorinated backbone; (b) pendant groups derived from an ionomeric monomer of the formula where X is F, Cl or Br or mixtures thereof; n is an integer equal to zero, one or two; R f and R f′ are independently selected from the group of F, Cl, perfluoroalkyl radical, and chloroperfluoroalkyl radical; Y is an acid group or a functional group convertible to an acid group; a is zero or an integer greater than zero; and b is an integer greater than zero; and (c) pendant groups derived from a vinyl ether monomer that has at least two vinyl ether groups of the form, CA 2 ═CB—O—, where the vinyl groups are separated by greater than four atoms; A is independently selected from the group containing F, Cl, and H; and B is independently selected from F, Cl, H and OR i , where R i is a branched or straight chain alkane that may be partially, substantially or completely fluorinated or chlorinated; wherein the concentration of the pendant groups derived from the ionomeric monomer and the vinyl ether monomer is between about 10 mole percent and about 45 mole percent of the final product, and wherein the concentration of the pendant groups derived from the vinyl ether monomer is present in the final product between about 0.05 and about 2 mole percent.