Patent ID: 7879506

Claim:
A solid polymer electrolyte membrane, comprising: a polymer compound, with a side chain including a unit represented by Formula (a), positioned at a heterocyclic nitrogen atom of a polybenzimidazole, wherein the concentration of the unit represented by Formula (a) is about 20 mol % to about 2000 mol % per repeated unit of the polybenzimidazole, and the polymer compound is obtained by reacting a polymer 2 with vinyl phosphonic acid represented by formula (a-0), and the polymer 2 is obtained by reacting the polybenzimidazole with a molecule that includes an isocyanate group or a glycidyl group and a C—C double bond wherein said molecule that includes an isocyanate group or a glycidyl group and a C—C double bond is at least one of 2-isocyanatoethylmethacrylate represented by formula (c-1), 2-isocyanatoethylacrylate represented by formula (c-2), and glycidylmethacrylate represented by formula (c-3)