Highly Sulfonated Poly(phenylene sulfone): Preparation and Stability Issues

Abstract

This paper presents a preparation route which allows the formation of a poly(phenylene) ionomer containing merely sulfone units (−SO2−) connecting the phenyl rings and in which each phenyl ring is monosulfonated (100% degree of sulfonation). This corresponds to an ion exchange capacity (IEC) of 4.5 mequiv g−1 (equivalent weight of EW = 220 g equiv−1). The preparation succeeded in a two-step process comprising a polycondensation reaction of sulfonated difluorodiphenyl sulfone with sodium sulfide, yielding sulfonated poly(phenylene sulfide sulfone), and the subsequent oxidation to the corresponding sulfonated poly(phenylene sulfone). The polymer was characterized by elemental analysis, NMR, IR, GPC, viscosity measurement, TGA in air and in pure water vapor atmosphere, DSC at low and high temperatures, and ac impedance spectroscopy. Room temperature water absorption isotherms have been determined by equilibrating samples at different relative humidities. Under the chosen reaction conditions, polymers with mo...