Synthesis and properties of sulfonated poly(arylene ether) block copolymers as proton conductive membranes

A new series of poly(arylene ether sulfone) multiblock copolymers were synthesized by polycondensation of linear and rigid hydrophobic and densely sulfonated hydrophilic oligomers. Thin membranes were prepared therefrom by solution casting and their properties were compared with those of Nafion and other poly(arylene ether sulfone) multiblock copolymers containing perfluorinated biphenylene moieties. The membranes showed good water affinity, high proton conductivity, low hydrogen and oxygen permeability, high mechanical strength, and reasonable oxidative stability. These properties are attractive as an electrolyte for polymer electrolyte membrane fuel cells. It was found that the perfluorinated biphenylene moieties as connecting groups for hydrophilic and hydrophobic blocks affected only slightly the properties of poly(arylene ether sulfone) multiblock copolymer membranes.