Preparation of porous fluoropolymer membranes by ion beam irradiation; Diameter control of "Track-Etched" pores

Yamaki, Tetsuya; Koshikawa, Hiroshi; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*

Poly(vinylidene fluoride) (PVDF) thin films were irradiated with different kinds of ion beams and then exposed to a 9 M KOH aqueous solution. Based on the results of SEM observations and conductometric analyses, the heating at 120C was found to enhance the etch rate in the latent track without changing that in the non-irradiated part, thereby enabling us to obtain very high etching sensitivity for the preparation of nano-sized pores. The formation of oxidized species during this pretreatment should facilitate the introduction of the etching agent to improve etchability. Additionally, the irradiation with higher-mass ions was preferable to achieve high sensitivity of the etching.