Improvement of synthesis procedure and characterization of sulfonated poly(arylene ether sulfone) for proton exchange membranes

A series of poly(arylene ether sulfone)s and sulfonated poly(arylene ether sulfone)s (SPSU-BP and SPSU-TP) were produced by improved direct synthesis procedure using difluorodiphenylsulfone. According to this procedure, the azeotropic agent, toluene or chlorobenzene for removal of water formed during the polymerization was unnecessary and the polymerization could be performed at lower temperature(similar to 130 degrees C). The membranes made of sulfonated copolymers with the mole ratio of sulfonated monomers of 40-50% were found to be suitable for proton exchange membrane applications. The membranes made of SPSU-BP-50 and SPSU-TP-40 showed higher conductivities (0.18 and 0.12 S/cm, at 25 degrees C) and excellent H-2/O-2 fuel cell performance. The sulfonated copolymers also showed comparable thermal stabilities, which make them promising candidates for proton exchange membrane fuel cell application