Patent ID: 7202001

Claim:
A polymer electrolyte membrane (PEM) comprising a sulfonated copolymer having a formula: where R 1 or R 2 is a single bond, cycloaliphatic, where R 3 is aryl ketone, aryl sulfone, aryl nitrile, and substituted aryl nitrile, wherein a, b, c and d are mole fractions of the monomer present in the copolymer where each are independently, from 0.01 to 1; wherein X is a hydrogen atom; wherein when R 3 is aryl ketone and R 1 and R 2 are the same, R 1 and R 2 are not —S—; and wherein said PEM is permeable to proton and has a proton flux greater than 0.005 S/cm.