Preparation of PTFE-based fuel cell membranes by combining the latent track formation technology with graft polymerization

Yoshida, Masaru; Kimura, Yosuke; Chen, J.; Asano, Masaharu; Maekawa, Yasunari

The development of polymer electrolyte fuel cell membranes with a higher proton conduction pathway in the thickness direction of the film is advanced by introduction of graft chains in the latent tracks zone formed along the swift heavy ion with both the UV-grafting and the -grafting. In this study, polytetrafluoroethylene (PTFE) film was irradiated with ion species of 450 MeV Xe and 56 MeV N, to obtain the iPTFE film. The iPTFE proton-conducting membranes with an ion-exchange capacity of 0.4-0.6 mmol/g were prepared in the UV- and -grafting methods. The proton conductivity () in the thickness direction of the PTFE-specimen without ion-beam irradiation was obtained to be 0.03 S/cm. In contrast to this, the value of the iPTFE proton-conducting membranes reached both up to 0.08 S/cm in two methods, when the Xe ions with a fluence of 310 ions/cm were irradiated.