Patent ID: 7258941

Claim:
A polyelectrolyte for a solid polymeric fuel cell, comprising: an aromatic polyether sulfone block copolymer comprising a hydrophilic segment containing sulfonic acid groups and a hydrophobic segment having no sulfonic acid groups, wherein, the hydrophilic segment weight fraction W2 to hydrophobic segment weight fraction W1 ratio falls in the range of 0.7<W2/W1<2.0, and the hydrophilic segment comprises a structural unit represented by chemical formula (2) into which sulfonic acid groups are introduced: wherein R1 represents C(═O) or S(═O) 2 , Ar represents a divalent aromatic residual group, m represents an integer of 3 to 1500, and the sulfonic acid groups are introduced to an aromatic ring selected from the group consisting of at least one of the aromatic rings bonded to R1, an aromatic ring of Ar and combinations thereof.