Characterization of ion-exchange membranes prepared by ion irradiation graft polymerization method and -ray irradiation graft polymerization method

Goto, Mitsuaki*; Omori, Masayuki*; Yamaki, Tetsuya; Sawada, Shinichi; Koshikawa, Hiroshi; Kitamura, Akane; Higa, Mitsuru*

We have prepared cation exchange membranes for applications to electrochemical energy-conversion devices by swift-heavy-ion irradiation, and then investigated their charge density, , a concentration of fixed charge groups, in comparison with that of the conventional -ray-grafted membranes. Poly(ethylene--tetrafluoroethylene) films with a 25 m thickness were irradiated in a vacuum chamber with 560 MeV Xe and subsequently immersed in a grafting solution containing sodium -styrenesulfonate at 60C. The charge density was estimated through the measurement of the membrane potential in an aqueous solution of potassium chloride. Our membranes exhibited higher charge density (reaching 2.40 mol/dm at maximum) than the -ray-grafted samples probably due to track structures characteristic of the bombarding heavy ions.