Synthesis of Poly(2,5‐benzimidazole) for Use as a Fuel‐Cell Membrane

Abstract

Abstract Summary: Poly(2,5‐benzimidazole) (ABPBI) was synthesized in a novel polymerization medium containing CH 3 SO 3 H and P 2 O 5 . 3,4‐Diaminobenzoic acid, a monomer for ABPBI, is soluble in the medium and the polymerization was therefore performed in a homogeneous state. It produced polymer fibers, thus simplifying the work‐up process. The membrane was cast directly from the polymerization mixture. Proton conductivities of the ABPBI membranes ranged from 0.02 to 0.06 S · cm −1 above 100 °C, without humidification, and the tensile strength of the membrane was approximately 100 MPa. Synthesis of ABPBI in a medium containing methanesulfonic acid and P 2 O 5 . image Synthesis of ABPBI in a medium containing methanesulfonic acid and P 2 O 5 .