Effect of Surface-Sulfonated Silica on the Properties of Pyridine-Containing Polybenzimidazoles

Resumo

Hybrid membranes based on pyridine-containing polybenzimidazole (PBI–Py) and silica containing sulfonic groups on the surface have been synthesized by two methods, namely, by casting a polymer solution with ready-prepared oxide particles and with a precursor for their synthesis. The effect of the synthesis method on the morphology, conductivity under various conditions, and gas permeability of the hybrid membranes has been studied. It has been shown that the membrane modification with silica leads to an increase in conductivity at a low silica content (2–5 wt %) and an increase in gas permeability. The highest proton conductivity (58 mS/cm at 160°C) has been found for the sample synthesized by casting a PBI–Py solution with a precursor that contains 2 wt % of silica modified with sulfonic groups. Possible mechanisms of proton transport in the synthesized systems have been discussed.