Ion-track membranes of fluoropolymers; LET-dependent track etching allows controlling pore size and shape
フッ素系高分子のイオン穿孔膜; LETに敏感なエッチング挙動で孔径・形状を制御する
八巻 徹也; Nuryanthi, N.*; 越川 博; 浅野 雅春; 澤田 真一; 前川 康成; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*
Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*
従来から検討がなされてきたポリエチレンテレフタレートやポリカーボネートなどの炭化水素系高分子ではなく、フッ素系高分子、特にポリフッ化ビニリデン(PVDF)からなるイオン穿孔膜に着目し、そのエッチング挙動や応用性に関する研究を進めている。今回、PVDFの穿孔形成が、潜在飛跡の構造を決める重要なパラメータである線エネルギー付与(LET)に強く依存することを見いだした。また、この知見を利用して、LETの深さ変化によるイオン穿孔の形状制御にも成功した。
Ion-track membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymer, have been used for many applications due to its superior chemical and mechanical properties. In order to produce track-etched pores in PVDF films, a highly-concentrated alkaline solution with an oxidizing agent has mostly been used at a high temperature, yet this provides irreversible chemical damage over the entire film including the non-irradiated part. We have independently employed much milder etching conditions without any oxidant additives in the alkaline etching solution. Because of the resulting negligibly-slow bulk etching, the finally-reaching plateau pore diameter could depend solely on the dose (or damage) distribution in each track. Therefore, we investigated here the effect of the track structure on etching behavior using different bombarding ions, and our finding on LET-sensitive track etching was applied to size and shape control of the obtained pores.