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Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Sawada, Shinichi; Hakoda, Teruyuki; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*
no journal, ,
We investigated the track-structure-dependent pore formation by scanning electron microscopy and conductometry to control the pore size and shape by direct use of the irradiation effect. PVDF films of 25 and 100 
m thicknesses were bombarded with heavy ions in the energy range between a few hundred MeV and GeV, and then etched in a 9 M KOH aqueous solution at 80
C. A very low bulk-etch rate was seen because of the mild etching conditions and high chemical stability of pristine PVDF. This finding suggests that the differences in the track structure, mainly depending on the LET, would be the most crucial factor of the resulting pore size. The depth distribution of the LET was applied to control the pore shape, in other words, to prepare nanopores with a conical as well as cylindrical shape. Importantly, direct use of the ion-beam irradiation effect without any concern for etching conditions provided this controllability.
Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Maekawa, Yasunari; Yamamoto, Kazuya*; Sampei, Fumihiro*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*
no journal, ,
We prepared new membrane materials by radiation techniques for application in alkaline fuel cells, especially in direct hydrazine fuel cells. Our unique method based on radiation-induced crosslinking and grafting, which previously proved to be an effective way of obtaining high-performance proton exchange membranes, has been used for developing anion-exchange membranes superior to those by the conventional radiation grafting. New attempts here were the 
-ray crosslinking of the poly(ethylene-co-tetrafluoroethylene) base film and chloromethylstyrene grafting with addition of a chemical crosslinker, divinylbenzene. The crosslinked anion-exchange membranes exhibited high OH
conductivity in their fully hydrated state and low water uptake, implying practical usefulness of our method.