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-tetrafluoroethylene) films using different mediaNuryanthi, 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 
m-thick ETFE film was irradiated in a vacuum chamber with 560 MeV 
Xe at different fluences, and then the grafting was performed by immersing the irradiated films in a 20vol% VBC monomer at 60
C. A medium was a mixture of water (H
O) and isopropyl alcohol (iPrOH) at different volume ratios. The degree of grafting increased as the HO content became higher, and reached a maximum in pure HO. 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.
-ray-induced graftingNuryanthi, N.*; Yamaki, Tetsuya; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Hasegawa, Shin; Asano, Masaharu; Maekawa, Yasunari; Suzuki, Akihiro*; et al.
no journal, ,
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 m-thick ETFE film was irradiated in a vacuum chamber with 560 MeV Xe at different fluences, and then the grafting was performed by immersing the irradiated films in a 20vol% VBC monomer at 60C. A medium was a mixture of water (HO) and isopropyl alcohol (iPrOH) at different volume ratios. The degree of grafting increased as the HO content became higher, and reached a maximum in pure HO.
Yamaki, Tetsuya; Nuryanthi, N.*; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Asano, Masaharu; Maekawa, Yasunari; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Heavy ions at kinetic energies typically from several hundreds of MeV to a few GeV passing through a polymer substrate induce a continuous trail of excitations and ionizations called latent tracks. We used a direct ion-track grafting method for preparation of anion exchange membranes for fuel cells. The functional anion exchange groups were introduced inside the latent tracks, thereby achieving OH
-conductive channels through the thickness. These straight channels increased conductivities, while the isolated cylindrical structure of tracks restricted the water uptake.
Yamaki, Tetsuya; Nuryanthi, N.*; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Asano, Masaharu*; Maekawa, Yasunari; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
We investigated the ion-track grafting of vinylbenzyl chloride (VBC) into a poly(ethylene-
-tetrafluoroethylene) (ETFE) film using different grafting media for applications as anion exchange membranes for fuel cells. In an attempt to increase the grafting yield, we applied a poor solvent system as the grafting medium, 
, a mixture of water and isopropyl alcohol (HO-
PrOH mixture). The optimum HO-PrOH composition was identified by the kinetic parameters including the initial polymerization rate (r
), the radical recombination rate () and the grafting efficiency (r/). These parameters changed depending on the VBC-grafting/chain-transfer reaction competition for the radicals on ETFE and the Trommsdorff effect; the swelling of the grafting substrate gave an additional effect.
-tetrafluoroethylene) filmsNuryanthi, N.*; Yamaki, Tetsuya; Saiki, Seiichi; Kitamura, Akane; Koshikawa, Hiroshi; Yoshimura, Kimio; Sawada, Shinichi; Terai, Takayuki*
no journal, ,
This study deals with the ion-track grafting of vinylbenzyl chloride (VBC) into poly(ethylene--tetrafluoroethylene) (ETFE) film irradiated with 560 MeV Xe and 330 MeV 
Ar for the application to anion exchange membrane fuel cells (AEMFC). The accelerated ions with different masses and energies enabled us to clarify the effect of the LET and radial dose distribution in the track on the ETFE film. The lower-LET Ar ion gave the higher degree of VBC grafting than the higher-LET Xe ion although its radial dose distribution showed smaller track size. This study gave an insight of the importance to study the track structure in relation with the final membrane properties of the AEMFC.
Nuryanthi, N.*; Yamaki, Tetsuya; Kitamura, Akane; Koshikawa, Hiroshi; Sawada, Shinichi; Yoshimura, Kimio; Terai, Takayuki*
no journal, ,
Swift heavy ions with kinetic energies of MeV to GeV will create cylindrical tracks along their trajectories in a polymer film. These tracks of tens to hundreds nanometers in diameter contain free radicals; they can be used as initiators for graft polymerization. The so-called ion-track grafting technique was used for the development of anion exchange membranes (AEMs). The OH conductivities at 60C in the fully-hydrated state were higher for ion-track-grafted membranes than for the conventional -ray-grafted ones at the certain same IEC. Due to a lower diffusion coefficient of OH, improving the conductivity has been one of the most challenging problems in AEM studies. In this sense, we found the ion-track grafting to be very promising.
