The effect of imidazolated PPO with different alkyl chains on its performance as a high temperature proton exchange membrane

Designed and synthesized a series of imidazolium-functionalized Poly (2, 6-dimethyl-1, 4-phenylene oxide) (Im-PPO) containing pendant imidazole groups, which were used to supply functional sites for acid–base interaction with the doping phosphoric acid. The imidazolium-functionalized Poly (2, 6-dimethyl-1, 4-phenylene oxide) membranes obtained by the solution-casting method were doped with phosphoric acid (PA). The PA content, swelling, and tensile strength of the different membranes doped with PA were measured. With the increase of the length of side chains on the imidazole groups, the membrane showed different properties. The proton conductivity at a level of 3.7 × 10⁻² S/cm was achieved at 160°C by the MeIm-PPO imidazolium composite membrane.