Phosphonated poly(arylene ether)s as potential high temperature proton conducting materials

The preparation and characterization of new phosphonated polymeric ionomers based on a fully aromatic poly(arylene ether) backbone with applications as proton exchange membranes for fuel cell is reported. The high-molecular-weight polymers were obtained by the polycondensation of the phosphonated monomers with decafluorobiphenyl in high yields with inherent viscosities up to 0.58 dL g−1. The hydrolysis of the phosphonated ester into phosphonic acid groups was carried out quantitatively under acidic conditions. The polymers were studied by TGA after hydrolysis and showed10% weight loss above 430 °C. Membranes with total ion-exchange capacities above 6 meq/g showed proton conductivities of approximately92 mS/cm at 25 °C and 100% relative humidity increasing to ca.150 mS/cm at 140 °C. Their conductivity under dry condition showed values over 2 mS/cm at 120 °C which upon doping with phosphoric acid jumped to nearly 100 mS/cm.