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Journal Articles

Fluoropolymer-based nanostructured membranes created by swift-heavy-ion irradiation and their energy and environmental applications

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:1 Percentile:75.54(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.

Journal Articles

Ion-track grafting of vinylbenzyl chloride into poly(ethylene-$$co$$-tetrafluoroethylene) films using different media

Nuryanthi, N.*; Yamaki, Tetsuya; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Suzuki, Akihiro*; et al.

Transactions of the Materials Research Society of Japan, 40(4), p.359 - 362, 2015/12

The ion-track grafting of a vinylbenzyl chloride (VBC) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film is necessary for preparing nanostructured hydroxide-ion-conductive electrolyte membranes. A key for success here is to obtain as high graft levels as possible (for higher conductivity) in a smaller number of tracks (for improving the other membrane properties). To this end, therefore, the effect of the medium for the VBC grafting was investigated as part of our continuing effort to optimize the experimental conditions. A 25 $$mu$$m-thick ETFE film was irradiated in a vacuum chamber with 560 MeV $$^{129}$$Xe at different fluences, and then the grafting was performed by immersing the irradiated films in a 20vol% VBC monomer at 60$$^{circ}$$C. A medium was a mixture of water (H$$_{2}$$O) and isopropyl alcohol (iPrOH) at different volume ratios. The degree of grafting increased as the H$$_{2}$$O content became higher, and reached a maximum in pure H$$_{2}$$O. These results can be explained by considering the well-known Trommsdorff effect, in which poor solubility of the grafted polymer in polar media leads to an increased polymerization rate probably due to a lower termination rate.

Journal Articles

Ion-track membranes of fluoropolymers; Toward controlling the pore size and shape

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:2 Percentile:77.33(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.

Journal Articles

Applied-voltage dependence on conductometric track etching of poly(vinylidene fluoride) films

Nuryanthi, N.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hasegawa, Shin; Maekawa, Yasunari; Katsumura, Yosuke*

Nuclear Instruments and Methods in Physics Research B, 314, p.95 - 98, 2013/11

 Times Cited Count:2 Percentile:77.33(Instruments & Instrumentation)

Our efforts have been focused on ion-track etched membranes of poly(vinylidene fluoride) (PVDF). This study deals with the effect of the transmembrane potential applied during the conductometry in order to offer a higher degree of freedom to control the pore size. We can say that higher voltage application during the conductometry would accelerate the etching in the tracks. The electrophoretic migration of dissolved products occurring out of each pore might be one of the reasons for this enhanced pore evolution and growth.

Journal Articles

Ion-track membranes of poly(vinylidene fluoride); Etching characteristics during conductomeric analysis

Nuryanthi, N.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hasegawa, Shin; Maekawa, Yasunari; Katsumura, Yosuke*

Transactions of the Materials Research Society of Japan, 38(1), p.105 - 108, 2013/03

We report here how conditions of the conductometric analysis affected the etching characteristics of 25 $$mu$$m-thick poly(vinylidene fluoride) film irradiated with 450 MeV $$^{129}$$Xe ions. The etching was performed in a 9 mol dm$$^{-3}$$ aqueous potassium hydroxide solution at 80$$^{circ}$$C in a conductometric cell. According to the scanning electron microscope observations, the ion-track membrane obtained with an applied AC voltage of 1.0 V had the surface pores of 168$$pm$$20 nm in diameter. On the other hand, the etching without an applied voltage gave the approximately two-thirds smaller pores. The conductomeric etching would provide a higher degree of freedom for controlling the pore diameter.

Journal Articles

Investigation of nanopore evolution in track-etched poly(vinylidene fluoride) membranes

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

Transactions of the Materials Research Society of Japan, 37(2), p.223 - 226, 2012/06

The aim of this study is to investigate the formation of the poly(vinylidene fluoride) (PVDF) track membranes in detail by electrolytic conductometry. A PVDF film was irradiated with a 450 MeV $$^{129}$$Xe or 2.2 GeV $$^{197}$$Au ion beam, and then the latent tracks were etched in a 9 mol dm$$^{-3}$$ aqueous KOH solution at 80$$^{circ}$$C that had been poured into a conductometric cell. At the same time, the evolution of cylindrical nanopores was monitored by measuring the conductance through the membrane. The etching kinetics significantly depended on the deposited energy within each track, which is represented by the LET. Interestingly, applying a higher voltage to the cell promoted track etching up to the breakthrough probably because the electrophoretic migration of dissolved products occurred out of each pore.

Journal Articles

Conductometric analysis for the formation of poly(vinylidene fluoride)-based ion track membranes

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

ECS Transactions, 35(24), p.1 - 12, 2011/05

 Times Cited Count:6 Percentile:5.01

Our focus has been placed on ion track membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymer, because of their superior chemical, mechanical and ferro-electric properties. The aim of this study is to investigate the formation of the PVDF track membranes in more detail by electrolytic conductometry. Interestingly, application of a higher voltage to the conductometry cell as well as irradiation with a higher-LET beam promoted track etching up to breakthrough probably because electrophoretic migration of dissolved products occurred out of each pore.

Journal Articles

Poly(vinylidene fluoride)-based ion track membranes with different pore diameters and shapes; SEM observations and conductometric analysis

Nuryanthi, N.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Enomoto, Kazuyuki; Sawada, Shinichi; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*

Denki Kagaku Oyobi Kogyo Butsuri Kagaku, 78(2), p.146 - 149, 2010/02

 Times Cited Count:6 Percentile:84.17(Electrochemistry)

Poly(vinylidene fluoride) (PVDF) membranes with conical and cylindrical nanopores were prepared in a controlled manner by the ion-track technique, which involved heavy ion beam irradiation and the subsequent alkaline etching. Etching behavior mainly depended on energy deposition of ion beams, and thus its depth distribution, estimated by theoretical simulation, was successfully applied to control the shapes and diameters of the etched pores. Scanning electron microscopy (SEM) and electrolytic conductometry then gave an insight into critical experimental parameters. Interestingly, applying a higher voltage to the conductometry cell promoted track etching up to breakthrough probably because electrophoretic migration of dissolved products occurred out of each pore.

Oral presentation

Preparation of porous fluoropolymer membranes by ion beam irradiation; Size and shape control of "track-etched pores"

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

no journal, , 

Although the ion-track technique has mainly been studied on a series of hydrocarbon polymers such as polycarbonate and polyethylene terephthalate, our focus has been placed on ion track membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymers, because of superior chemical, mechanical and ferro-electric properties. In this study, PVDF membranes with conical and cylindrical nanopores were prepared in a controlled manner by the ion-track technique, which involved ion-beam irradiation and the subsequent alkaline etching. Etching behavior mainly depended on energy deposition of ion beams, and thus its depth distribution, estimated by theoretical simulation, was successfully applied to control the shapes and diameters of the etched pores.

Oral presentation

Preparation of fluoropolymer-based porous membranes by ion beam irradiation; Size and shape control of track-etched pores

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

no journal, , 

Poly(vinylidene fluoride) (PVDF) membranes with conical and cylindrical nanopores were prepared in a controlled manner by the ion-track technique, which involved heavy ion beam irradiation and subsequent alkaline etching. The etching behavior mainly depended on the energy deposition of the ion beams, and thus its depth distribution, estimated by theoretical simulation, was successfully applied to control the shapes and diameters of the etched pores. Scanning electron microscopy (SEM) and electrolytic conductometry provided an insight into the critical experimental parameters.

Oral presentation

Preparation of porous fluoropolymer membranes by ion beam irradiation; Size and shape control of "Track-Etched Pores"

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

no journal, , 

Poly(vinylidene fluoride) (PVDF) membranes with conical and cylindrical nanopores were prepared in a controlled manner by the ion-track technique, which involved heavy ion beam irradiation and subsequent alkaline etching. The etching behavior mainly depended on the energy deposition of the ion beams, and thus its depth distribution, estimated by theoretical simulation, was successfully applied to control the shapes and diameters of the etched pores. Scanning electron microscopy (SEM) and electrolytic conductometry provided an insight into the critical experimental parameters.

Oral presentation

Preparation of fluoropolymer-based ion-track membranes; Conductometric analysis of track-etching behavior

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

no journal, , 

Poly(vinylidene fluoride) (PVDF) membranes with cylindrical nanopores were prepared in a controlled manner by the ion-track technique, which involved ion-beam irradiation and the subsequent alkaline etching. As is well-known, etching behavior appeared to depend on energy deposition of ion beams, i.e., linear energy transfer (LET) and radial dose distribution in a latent track. Electrolytic conductometry then gave an insight into critical experimental parameters. Interestingly, applying a higher voltage to the conductometry cell promoted track etching up to breakthrough probably because electrophoretic migration of dissolved products occurred out of each pore.

Oral presentation

Pore size and shape control of fluoropolymer-based ion-track membranes; Direct use of irradiation effect

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 $$mu$$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$$^{circ}$$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.

Oral presentation

Ion-track membranes of fluoropolymers; LET-dependent track etching allows controlling pore size and shape

Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Maekawa, Yasunari; Voss, K.-O.*; Trautmann, C.*; Neumann, R.*

no journal, , 

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.

Oral presentation

Investigation on etching characteristics of ion-track membranes of poly(vinylidene fluoride) by SEM observation

Nuryanthi, N.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hasegawa, Shin; Maekawa, Yasunari; Katsumura, Yosuke*

no journal, , 

We prepared ion-track membranes of poly(vinylidene fluoride) by chemical etching in a conductometric cell and then investigated how the applied AC voltage affected etching characteristics using scanning electron microscopy. The high voltage application had some effect on the final pore diameter, which seems inconsistent with the findings of our previous conductometric analysis, while shortening the breakthrough time greatly.

Oral presentation

Preparation of fluoropolymer-based ion-track membranes; Structure of latent tracks and pretreatment effect

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 $$mu$$m-thick PVDF film was bombarded with 1.1 GeV $$^{238}$$U or 450 MeV $$^{129}$$Xe ions. According to the ${it in-situ}$ 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.

Oral presentation

Applied-voltage dependence on conductometric track etching of poly(vinylidene fluoride) films

Nuryanthi, N.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hasegawa, Shin; Maekawa, Yasunari; Katsumura, Yosuke*

no journal, , 

We prepared ion-track membranes of poly(vinylidene fluoride) by chemical etching in a conductometric cell and then investigated how the applied AC voltage affected etching characteristics using scanning electron microscopy. The high voltage application had some effect on the final pore diameter, which seems inconsistent with the findings of our previous conductometric analysis, while shortening the breakthrough time greatly.

Oral presentation

Preparation of fluoropolymer-based ion-track membranes; control of pore size and shape by track structures

Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Sawada, Shinichi; Asano, Masaharu; Maekawa, Yasunari; Voss, K.-O.*; Christina, T.*

no journal, , 

Our focus has been placed on ion-track membranes of poly(vinylidene fluoride) (PVDF), a type of fluoropolymer. Here 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. According to the study of the films irradiated with different ions, the diameter of the etched pores actually depended on the deposited energy within each track represented by the linear energy transfer (LET). The depth distribution of the LET was then applied to control the pore shape, in other words, to prepare nanopores with a conical as well as cylindrical shape.

Oral presentation

Pore formation by track etching of poly(vinylidene fluoride) films; Dependence on applied voltages during conductometric analysis

Yamaki, Tetsuya; Nuryanthi, N.*; Koshikawa, Hiroshi; Sawada, Shinichi; Asano, Masaharu; Maekawa, Yasunari; Katsumura, Yosuke*

no journal, , 

A poly(vinylidene fluoride) film irradiated with 450 MeV $$^{129}$$Xe ions was etched in an aqueous potassium hydroxide solution at 80$$^{circ}$$C in a conductometric cell. The etching characteristics were investigated in situ at different applied voltages. The conductometric curves reached a plateau when the etching time was sufficiently long (up to 48 h); this plateau indicates that etching was complete in the damaged track and that the bulk etch rate was negligibly low. The applied voltage produced larger pores than the etching with no voltage. Higher voltages shortened the etching time; the voltage accelerated the etching before the pore breakthrough and during the pore growth. The increase in the etch rate was probably caused by the dissolved etching products being pulled away from the pores more efficiently at higher applied voltages.

Oral presentation

Investigation on etching characteristics of ion-track membranes of poly(vinylidene fluoride) by SEM observation

Nuryanthi, N.*; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Sawada, Shinichi; Hasegawa, Shin; Kitamura, Akane; Maekawa, Yasunari; Katsumura, Yosuke*

no journal, , 

We prepared ion-track membranes of poly(vinylidene fluoride) by chemical etching in a conductometric cell and then investigated how the applied AC voltage affected etching characteristics using scanning electron microscopy. The high voltage application had some effect on the final pore diameter, which seems inconsistent with the findings of our previous conductometric analysis, while shortening the breakthrough time greatly.

27 (Records 1-20 displayed on this page)