Synthesis and characterization of crosslink-free highly sulfonated multi-block poly(arylene ether sulfone) multi-block membranes for fuel cells

Abstract

A block sulfonated poly(arylene ether sulfone) copolymer (SPAES) was synthesized through nucleophilic aromatic substitution between hydrophilic and hydrophobic oligomeric precursors. Highly sulfonated hydrophilic block polymers were designed and the resultant block membrane showed very high proton conductivity even under low RH: 0.48 and 0.035 S cm⁻¹ at 90% and 40% RH, respectively, at 80 °C; these values were higher than that of a commercial PFSA membrane. The fuel-cell performance reached 250 mA cm⁻² at 0.7 V at 120 °C, 40% RH, and atmospheric conditions.