Development of a proton exchange membrane based on trifluoromethanesulfonylimide-grafted polybenzimidazole

Hoon Han, Hiroto Miura, Yuki Motoishi, Naoki Tanaka, Tsuyohiko Fujigaya

    Research output: Contribution to journalArticlepeer-review


    Trifluoromethanesulfonylimide-grafted polybenzimidazole (PBI-TFSI) was synthesized for proton exchange membrane (PEM) applications. Its proton conductivity was (a) less dependent on humidity and (b) higher than that of conventional fluorine-based PEM (Nafion) and propanesulfonic acid-grafted PBI (PBI-PS) at a relative humidity of 40%. The chemical structure of PBI-TFSI was investigated using 1H and 19F nuclear magnetic resonance and Fourier transform infrared spectroscopy. The membranes exhibited good transparency, flexibility, and thermal stability up to 350 °C. Membranes with different side chain grafting ratios were prepared, and the water uptake and hydration number of the PBI-TFSI membranes were lower than those of the PBI-PS membranes, most likely because of the hydrophobicity of the side chain. The higher proton concentration provided by TFSI with stronger acidity than PS might be the reason for the higher proton conductivities of PBI-TFSI.

    Original languageEnglish
    JournalPolymer Journal
    Publication statusAccepted/In press - 2021

    All Science Journal Classification (ASJC) codes

    • Polymers and Plastics
    • Materials Chemistry


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