Studies on proton conductivity of acid doped polybenzimidazole/polyimide and polybenzimidazole/polyvinyl pyrrolidone blends

Polybenzimidazole (PBI)/polyimide (PI) and PBI/polyvinylpyrrolidone (PVP) blends were prepared. All of these polymers are suitable for acid doping as a matrix because of the existence of the N-heterocycle in the polymers, which can eventually be used as proton conductors. The miscibility of PBI/PVP blend is confirmed by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM), while the miscibility of PBI/PI is already reported in references. Temperature dependence of proton conductivity of acid doped PBI/Pl and PBI/PVP blends are studied. As the temperature increases, proton conductivity of H3PO4 doped PBI/PVP blends increases. Temperature dependence of proton conductivity of the blends can still be fitted by a simple Arrhenius relation. The proton transport of the blend is similar to that of PBI. The methanol permeability of PBI/PI blends is also studied. Methanol permeability in PBI/PI, PI, and PBI membranes decreases with increasing methanol concentration.