NMR and electrical conductivity studies of poly(2,6-dimethyl-1,4-phenyleneoxide) ionomers

Different PPO-SH ionomers were obtained by sulfonation of poly(2,6-dimethyl-1,4-phenyleneoxide) (PPO). The sulfonation was assessed by FTIR and XPS spectroscopies. The acid form of the ionomers was characterized by means of 1H and 13C MAS-NMR spectroscopies. Then, polymers were hydrated under controlled humidity atmosphere and NMR and electrical conductivity studies performed. In the hydrated samples, two stages associated with formation of hydronium (H3O+) species and proton hopping between adsorbed water molecules have been deduced. Both processes participate in the conductivity of PPO-SH samples.