Blend membranes based on sulfonated poly(ether ether ketone) and polysulfone bearing benzimidazole side groups for proton exchange membrane fuel cells

A novel acid–base blend membrane based on sulfonated poly(ether ether ketone) (SPEEK) and polysulfone bearing benzimidazole side groups has been synthesized, characterized, and evaluated in proton exchange membrane fuel cell (PEMFC). The benzimidazole group tethered to the polysulfone backbone acts as a medium through the basic nitrogen for transfer of protons between the sulfonic acid groups of SPEEK, supporting a Grotthuss-type mechanism in addition to the vehicle-type mechanism present among SPEEK. The blend membrane exhibits better performance in PEMFC at 90 and 100 °C compared to the pure SPEEK and Nafion 115 membranes. The polymers bearing pendant benzimidazole groups offer a promising strategy to develop new membranes that can operate at higher temperatures and low relative humidity.