Preparation and properties of ion exchange membranes for PEMFC with sulfonic and carboxylic acid groups based on polynorbornenes

Bifunctional groups proton exchange membranes (PEMs) with sulfonic and carboxylic acid groups were prepared via ring-opening metathesis polymerization (ROMP) based on norbornene derivatives. The sulfonic acid groups and the carboxylic acid groups were introduced into the polymer chains in the form of sulfonyl chloride and ester separately. Because of the introduction of these two groups, not only greatly improve the proton conductivity of PEMs, but also improve their mechanical performance and thermal stability. When the highest proton conductivity of the bifunctional groups PEMs is 123.96 mS/cm, its proton conductivity is higher than that of Nafion® 117 at 25 °C.