Anisotropic proton-conducting membranes prepared from swift heavy ion-beam irradiated ETFE films

イオンビームによる異方性プロトン導電性膜の作製とその特性

木村 祥亮*; Chen, J.; 浅野 雅春; 前川 康成; 片貝 良一*; 吉田 勝

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

重イオンビームを利用し異方伝導経路を持つ固体高分子型燃料電池膜の開発を進めている。この目的に対し、ETFEフィルム基材に450MeVのキセノンイオンを照射することでナノ損傷領域からなる潜在飛跡を形成、次いで線グラフト重合法によりポリスチレングラフト鎖を導入、最終的にスルホン化工程を経て異方導電性電解質膜を作製した。

Poly(ethylene-co-tetrafluoroethylene) (ETFE) films were irradiated by swift heavy ion-beams, followed by pre-irradiation for radiation grafting of styrene onto the ETFE films and sulfonation of the grafted ETFE films to prepare highly anisotropic proton-conducting membranes. The fluence of Xe ions and the addition of water in the grafting solvent were examined to determine their effect on the proton conductivity of the resultant membranes. It was found that the polymer electrolyte membrane prepared by grafting the styrene monomer in a mixture of isopropanol and water to the ETFE film with a ion-beam irradiation fluence was a highly anisotropic proton-conducting material, as the proton conductivity was 3 or more times higher in the thickness direction than in the surface direction of the membrane.