Poly(arylene ether) Block Copolymer Membranes: Synthesis, Properties and Durability

Abstract

Poly(arylene ether sulfone)s (SPEs) block copolymers containing fluorenyl groups were synthesized for fuel cell applications. Postsulfonation of the polymers by chlorosulfonic acid gave sulfonated block copolymers having highly sulfonated hydrophilic block. SPE block copolymer membrane with the ion exchange capacity (IEC) = 2.20 meq/g showed proton conductivity, 0.14 S/cm (80% RH) and 0.02 S/cm (40% RH) at 80°C, which is higher or comparable to that of perfluorinated ionomer (Nafion®) membrane. STEM observation of Ag-stained membranes revealed that phase separation of the SPE block copolymers was more developed than that of the SPE random copolymers. Long-term hydrolytic stability of these membranes has been confirmed.