High-Temperature Hybrid Proton-Conducting Membranes Based on Cross-Linked Triazole-Functional Copolymer/Polyfluorinated Silsesquioxane

Flexible-chain azole-containing polymers incorporated into a rigid-chain organo-inorganic polymer backbone have excellent characteristics for the formation of proton-conducting membranes with a stable chemical structure. In the present study, a series of high-temperature hybrid proton-conducting membranes were synthesized by covalently cross-linking a flexible-chain triazole-containing copolymer with a fluorinated polysilsesquioxane framework via hydrolytic copolycondensation in the presence of a phosphoric acid dopant. The membrane components act synergistically, forming continuous long-range proton-conduction channels through acid–base pairs and a hydrogen-bond network. Owing to the fluorinated polysilsesquioxane framework, the resulting membranes exhibited excellent mechanical properties, good thermal stability up to 253 °C, high oxidative stability, low acid leaching rate, and low water uptake/swelling ratio, the indicators of which are significantly better than previously described analogues. Proton conductivity increased with increasing doping degree. Under anhydrous conditions, high-dopant-containing membranes exhibited a high proton conductivity of about 10 mS/cm at 180 °C with an activation energy of 16.4 kJ/mol. The results of this study demonstrate that the obtained high-performance hybrid membranes have potential for use as high-temperature proton-conducting membranes in fuel cells.