Synthesis and characterization of novel sulfonated poly(arylene ether phosphine oxide) with diphenyl ether moieties as proton exchange membranes

A series of novel sulfonated poly(arylene ether phosphine oxide)s containing diphenyl ether (sPEPO) with various sulfonation degrees were synthesized using direct polycondensation. The transparent, tough and flexible membranes could be obtained by casting. The macroscopic properties and microstructure of the obtained membranes were studied in detail. The results showed that these sPEPO membranes with appropriate sulfonation degree displayed excellent properties in terms of proton conductivity and dimensional stability. For example, sPEPO-80 exhibited a proton conductivity of 0.092 S cm−1, which is higher than that of Nafion 117 (0.088 S cm−1) at 80 °C, whereas a swelling of 21.1% at 80 °C is comparable to that 20.1% of Nafion 117. In addition, it took 60 h to dissolve completely in Fenton’s reagent at 25 °C, which presented remarkable oxidation stability. Therefore, the achieved sPEPO-80 membrane has an excellent application prospect.