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Yamaki, Tetsuya*; Nuryanthi, N.*; Kitamura, Akane; Koshikawa, Hiroshi*; Sawada, Shinichi*; Voss, K.-O.*; Severin, D.*; Tautmann, C.*
Nuclear Instruments and Methods in Physics Research B, 435, p.162 - 168, 2018/11
Times Cited Count：8 Percentile：62.99(Instruments & Instrumentation)We used individual single-ion tracks in fluoropolymers with diameters of tens to hundreds of nanometers; chemical etching and ion-track grafting enabled us to develop ion-track and proton-conductive membranes, respectively. In the ion-track membranes of PVDF, strongly-LET-dependent etching was found, so the pore shape as well as the size was exclusively controlled by the track structures. We performed the ion-track grafting of styrene into ETFE to develop nanostructure-controlled proton exchange membranes (PEMs) for applications in PEM fuel cells. Our ion beam technology to develop fluoropolymer-based nanostructures has the potential to apply in the field of filtration processes and fuel cell devices. This would make it possible to provide new microfiltration technology for water treatment, sterilization, petroleum refining and dairy processing.
Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hakoda, Teruyuki; Maekawa, Yasunari; Voss, K.-O.*; Severin, D.*; Seidl, T.*; et al.
Nuclear Instruments and Methods in Physics Research B, 314, p.77 - 81, 2013/11
Times Cited Count：3 Percentile：26.71(Instruments & Instrumentation)Ion-track membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymer, could find wide applications due to its superior chemical and mechanical properties. In order to produce track-etched pores in PVDF films, we have independently employed much milder etching conditions without any oxidant additives in the alkaline etching solution. The goal of this work is to pursue the possibility of varying beam parameters and applying the effect of the etching pretreatment to control the pore size and shape. Ongoing in-situ/on-line analyses at the M-branch of the UNILAC would shed light on the detailed chemistry of not only ion-induced degradation but also the post-irradiation reactivity.
Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Maekawa, Yasunari; Severin, D.*; Seidl, T.*; Trautmann, C.*
no journal, ,
There has been a strong motivation for us to investigate the detailed chemistry of heavy-ion-induced degradation. We report here the results of our first experiments in this regard done at the newly installed M-branch of UNILAC accelerator, GSI. Commercially-available 25 
m-thick PVDF films were irradiated at room temperature by 4.8 MeV/u 
U at fluencies of up to 6
10
ions/cm
. This irradiation was performed in the multi-purpose chamber of the M3 beamline equipped with a Fourier-transform infrared (FT-IR) transmission spectrometer as well as a residual gas analyzer. When irradiated at a fluence of 110
ions/cm, the film showed three new absorption bands, which can be identified as in-chain and chain-end unsaturations in the PVDF main chain. According to the analysis of outgassing fragments, hydrogen fluoride can be predicted as degradation product for the formation of these unsaturated bonds.
Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Sawada, Shinichi; Hakoda, Teruyuki; Asano, Masaharu; Maekawa, Yasunari; Voss, K.-O.*; Severin, D.*; Seidl, T.*; et al.
no journal, ,
We examined chemical structures of the defects in an ion track penetrating through poly(vinylidene fluoride) (PVDF), and accordingly, presented a pretreatment technique for achieving more efficient track etching. A 25 m-thick PVDF film was bombarded with 1.1 GeV U or 450 MeV 
Xe ions. According to the 
infra-red spectroscopy and residual gas analysis, the formation of many double bonds were found to occur in the PVDF main chain with the evolution of hydrogen fluoride. The knowledge of the solubility in a permanganate alkaline solution and our preliminary experiment suggested the importance of oxidized tracks for the easy introduction of the etching agent. We finally found that the pretreatment with ozone could oxidize the double bonds in the tracks, thereby vigorously promoting track etching before breakthrough.
Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Maekawa, Yasunari; Severin, D.*; Seidl, T.*; Trautmann, C.*
no journal, ,
We irradiated a poly(vinylidene fluoride) (PVDF) film with swift heavy ions, and then examined chemical structures of the defects created in the resulting track. The 25 m-thick PVDF film was bombarded with 1.1 GeV U ions in the multi-purpose chamber, where degradation processes were monitored by FT-IR spectroscopy and residual gas analysis as a function of the fluence. At fluences above 1.010 ions/cm, the film showed two new absorption bands identified as double-bond stretching vibrations of in-chain unsaturations and fluorinated vinyl groups. These defects would result from the evolution of HF, which was seen in the residual gas analysis and would be explained by a four-center mechanism.
Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hakoda, Teruyuki; Maekawa, Yasunari; Voss, K.-O.*; Severin, D.*; Seidl, T.*; et al.
no journal, ,
The possibility of varying the beam parameters and applying the effect of a pre-etching treatment for poly(vinylidene fluoride) (PVDF) ion-track membranes was investigated with the goal of achieving enhanced track etching for effective control of the pore size and shape. Commercially available 25 m-thick PVDF films were irradiated at room temperature with swift heavy ions. Irradiation with a higher-LET beam gave faster track etching and larger pores, suggesting that the LET could be the most crucial factor determining the pore size. In-situ infra-red absorption and residual gas analyses shed light on the detailed chemistry of not only the ion-induced degradation, but also post-irradiation reactions. The pre-etching treatment effect involved oxidation of the unsaturated bonds within the latent track, which accelerated the chemical dissolution for efficient pore evolution. In other words, exposure to a gaseous oxidant, i.e., ozone, shortened the breakthrough time.
Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Asano, Masaharu*; Sawada, Shinichi; Kitamura, Akane; Maekawa, Yasunari; Kay-Obbe, V.*; Severin, D.*; Seidl, T.*; et al.
no journal, ,
Practically, polyvinylidene fluoride (PVDF) has been said to be the only fluoropolymer in which ion tracks can be developed by chemical etching. We thus investigated the possibility of varying the beam parameters and applying the effect of a pre-etching treatment for PVDF ion-track membranes with the goal of achieving enhanced track etching for effective control of the pore size and shape. Our activities also cover all types of fluoropolymers including PVDF. Compared to PVDF, poly(ethylene-
-tetrafluoroethylene) and a series of perfluoropolymers are known to be very stable in highly-concentrated acid or alkaline solutions or at higher temperatures. Although this property might make their ion-track etching very challenging, the ongoing research is expected to allow one to accumulate know-how on methods of chemical etching, which can be generalized for the chemical structures. These will give feedback to a guiding principle for effective ion-track etching in fluoropolymers.
