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Journal Articles

Imidazolium cation based anion-conducting electrolyte membranes prepared by radiation induced grafting for direct hydrazine hydrate fuel cells

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Journal of the Electrochemical Society, 161(9), p.F889 - F893, 2014/06

 Times Cited Count:21 Percentile:61.11(Electrochemistry)

Graft-type anion-conducting electrolyte membranes (AEMs) with imidazolium cations on graft polymers were synthesized through radiation-induced graft polymerization of ${it N}$-vinylimidazole (NVIm) on poly(ethylene-co-tetrafluoroethylene) (ETFE) films, followed by ${it N}$-propylation and ion-exchange reactions. The ${it N}$-propylation proceeded quantitatively, whereas the ion-exchange reactions in 1 M KOH at 60$$^{circ}$$C were accompanied by partial $$beta$$-elimination of the imidazolium cations(AEM2), which exhibited an ion-exchange capacity (IEC) of 0.85 mmol g$$^{-1}$$ and ionic conductivity of 10 mS cm$$^{-1}$$. AEM2 showed alkaline stability at 60$$^{circ}$$C but it gradually degraded at 80$$^{circ}$$C for ca. 150 h. The copolymer-type AEM (AEM3) with an IEC of 1.20 mmol g$$^{-1}$$ was prepared through the copolymerization of NVIm with styrene on ETFE films, followed by the same ${it N}$-propylation and ion-exchange reactions. AEM3 was shown higher alkaline durability in 1 M KOH at 80$$^{circ}$$C. As a result, it exhibited higher conductivity ($$>$$10 mS cm$$^{-1}$$) for 250 h. Therefore, alkylimidazolium cations in copolymer grafts are a promising anion conducting group for alkaline-durable AEMs. A maximum power density of 75 mW cm$$^{-2}$$ is obtained for AEM3 in a direct hydrazine hydrate fuel cell.

Journal Articles

Counter-anion effect on the properties of anion-conducting polymer electrolyte membranes prepared by radiation-induced graft polymerization

Koshikawa, Hiroshi; Yoshimura, Kimio; Sinnananchi, W.; Yamaki, Tetsuya; Asano, Masaharu; Yamamoto, Kazuya*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Maekawa, Yasunari

Macromolecular Chemistry and Physics, 214(15), p.1756 - 1762, 2013/08

 Times Cited Count:15 Percentile:45.22(Polymer Science)

Graft-type anion-conducting polymer electrolyte membranes were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization with trimethylamine to evaluate the counter anion effects on fuel cell properties. The hydroxide form was maintained in -saturated water to prevent the bicarbonate formation. The hydroxide form showed conductivity and water uptake four and two times higher than the chloride and bicarbonate forms. The hydroxide form is thermally and chemically less stable, resulting in the tendency to absorb water and to convert to the bicarbonate form.

Journal Articles

Alkaline durable anion exchange membranes based on graft-type fluoropolymer films for hydrazine hydrate fuel cell

Yoshimura, Kimio; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

ECS Transactions, 50(2), p.2075 - 2081, 2012/10

no abstracts in English

Journal Articles

Preparation of anion-exchange membranes for fuel cell applications by $$gamma$$-ray pre-irradiation grafting

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*

Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.240 - 241, 2011/06

The anion-exchange membranes (AEM) for fuel cells were prepared by the radiation-induced graft polymerization of chloromethylstyrene into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization of the grafts with trimethylamine. When the AEM were treated in 1M-KOH and washed with N$$_{2}$$-saturated water, the membranes with chloride form can be converted quantitatively to hydroxide form. However, the hydroxide form was easily converted to the bicarbonate form by the treatment in non-bubbled (CO$$_{2}$$ dissolved) water. When we introduced the crosslinkers in polymer grafts, which is proved to be very effective in the proton conducting PEM having a poly(styrenesulfonic acid) grafts, the grafted AEM with both chloride and hydroxide forms showed only slight decrease of water uptake. It should be noted that AEM with hydroxide form showed very high tendency to absorb water.

Journal Articles

Anomalous degradation in silicon solar cells subjected to high-fluence proton and electron irradiations

Morita, Yosuke; Oshima, Takeshi; Nashiyama, Isamu; ; ; Matsuda, Sumio*

Journal of Applied Physics, 81(9), p.6491 - 6493, 1997/05

 Times Cited Count:22 Percentile:71.61(Physics, Applied)

no abstracts in English

Oral presentation

Preparation and characterization of PVDF-based photografted electrolyte fuel cell membranes

Yuzawa, Atsusuke*; Yamamoto, Toshinori*; Kuroda, Shinichi*; Kubota, Hitoshi*; Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Yoshida, Masaru

no journal, , 

no abstracts in English

Oral presentation

Preparation of anion-exchange membranes using ionizing radiation and their cell testing

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*

no journal, , 

We prepared anion-exchange membranes based on an ethylene-tetrafluoroethylene copolymer by $$gamma$$-ray-induced graft polymerization of chloromethylstyrene (CMS) and the subsequent quaternization reaction. The crosslinker effect was investigated in terms of membrane preparation and performance of a hydrazine fuel cell. The quaternization ratio appeared to decrease as the concentration of divinylbenzene (DVB) in the CMS grafting solution increased. Importantly, the crosslinker lowered the water uptake of the resulting membranes in the Cl$$^{-}$$ and OH$$^{-}$$ forms, possibly thereby restricting excessive swelling during the fuel-cell operation.

Oral presentation

Investigation of oxygen reduction reaction (ORR)on Pt-CeO$$_{x}$$ model interface for polymer electrolyte fuel cells

Fugane, Keisuke*; Mori, Toshiyuki*; Masuda, Takuya*; Uosaki, Kohei*; Yamamoto, Shunya; Maekawa, Yasunari

no journal, , 

no abstracts in English

Oral presentation

Preparation of anion-exchange membranes by radiation grafting

Asano, Masaharu; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*

no journal, , 

no abstracts in English

Oral presentation

Fuel cell performance of anion exchange polymer electrolyte membranes prepared by radiation-induced grafting

Maekawa, Yasunari; Sinnananchi, W.; Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Yamamoto, Kazuya*; Sampei, Fumihiro*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

Anion-exchange membranes (AEM) for hydrazine fuel cells, in which non precious metals are used as a electrode catalyst, were prepared using radiation techniques. The grafted AEM were prepared by the radiation-induced graft polymerization of chloromethylstyrene (CMS) into poly(ethylene-co-tetrafluoroethylene) (ETFE) films and subsequent quaternization of the grafts with trimethylamine. When the grafted AEM were treated in 1M-KOH and washed with N$$_{2}$$-saturated water, the membranes with chloride form (ETFE-TMAMS(Cl)) can be converted quantitatively to hydroxide form (ETFE-TMAMS(OH)) without the formation of the bicarbonate form. The grafted AEM with IEC of 2.0 mmol/g showed the maximum power density of more than 300 mW/cm$$^{2}$$ with stability for 400 hours under the operation at 80$$^{circ}$$C.

Oral presentation

Synthesis of novel anion conductive membranes by radiation-induced grafting; Basicity effect

Yoshimura, Kimio; Sinnananchi, W.; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

no abstracts in English

Oral presentation

Development of anion-exchange membranes by radiation grafting; Effect of crosslinker for swelling

Asano, Masaharu; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Sampei, Fumihiro*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

no abstracts in English

Oral presentation

Preparation of anion-exchange membranes using ionizing radiation and their cell testing

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Yoshimura, Kimio; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

We prepared anion-exchange membranes based on an ethylene-tetrafluoroethylene copolymer by $$gamma$$-ray-induced graft polymerization of chloromethylstyrene (CMS) and the subsequent quaternization reaction. The crosslinker effect was investigated in terms of membrane preparation and performance of a hydrazine fuel cell. The quaternization ratio appeared to decrease as the concentration of divinylbenzene (DVB) in the CMS grafting solution increased. Importantly, the crosslinker lowered the water uptake of the resulting membranes in the Cl$$^{-}$$ and OH$$^{-}$$ forms, possibly thereby restricting excessive swelling during the fuel-cell operation.

Oral presentation

Preparation of fuel cell membranes by UV-induced grafting of fluoropolymers

Yoshida, Masaru; Asano, Masaharu; Chen, J.; Maekawa, Yasunari; Yamamoto, Toshinori*; Kuroda, Shinichi*; Kubota, Hitoshi*

no journal, , 

no abstracts in English

Oral presentation

Preparation of anion-exchange membranes by radiation grafting and their cell testing; Effect of crosslinker

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*

no journal, , 

We prepared anion-exchange membranes based on an ethylene-tetrafluoroethylene copolymer by $$gamma$$-ray-induced graft polymerization of chloromethylstyrene (CMS) and the subsequent quaternization reaction. The crosslinker effect was investigated in terms of membrane preparation and performance of a hydrazine fuel cell. The quaternization ratio appeared to decrease as the concentration of divinylbenzene (DVB) in the CMS grafting solution increased. Importantly, the crosslinker lowered the water uptake of the resulting membranes in the Cl$$^{-}$$ and OH$$^{-}$$ forms, possibly thereby restricting excessive swelling during the fuel-cell operation.

Oral presentation

Development of anion-exchange membranes by using crosslinked ETFE films

Asano, Masaharu; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Sampei, Fumihiro*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Yamada, Koji*; Tanaka, Hirohisa*

no journal, , 

no abstracts in English

Oral presentation

Preparation of anion-exchange membranes using ionizing radiation and their cell testing; Swelling-suppression effect due to crosslinking of ETFE base films

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Maekawa, Yasunari; Yamamoto, Kazuya*; Sampei, Fumihiro*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Yamada, Koji*; Tanaka, Hirohisa*

no journal, , 

We prepared anion-exchange membranes based on $$gamma$$-ray crosslinked ethylene-tetrafluoroethylene copolymer (ETFE) by $$gamma$$-ray-induced graft polymerization of chloromethylstyrene (CMS) and the subsequent quaternization reaction. Little effect of radiation crosslinking was observed for the degree of CMS grafting and the quaternization ratio. Interestingly, however, the crosslinking structure in ETFE was found to lower water uptake of the resulting membranes in the OH form, thereby restricting excessive swelling during hydrazine-fuel-cell operation.

Oral presentation

Development of anion-exchange ETFE membranes by radiation grafting

Asano, Masaharu; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamamoto, Kazuya*; Sampei, Fumihiro*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

We prepared anion-exchange membranes based on an ethylene-tetrafluoroethylene copolymer by $$gamma$$-ray-induced graft polymerization of chloromethylstyrene (CMS) and the subsequent quaternization reaction. The crosslinker effect was investigated in terms of membrane preparation and performance of a hydrazine fuel cell. The quaternization ratio appeared to decrease as the concentration of divinylbenzene (DVB) in the CMS grafting solution increased. Importantly, the crosslinker lowered the water uptake of the resulting membranes in the Cl and OH forms, possibly thereby restricting excessive swelling during the fuel-cell operation.

Oral presentation

Synthesis and characterization of proton conducting membranes based on UV-grafted fluoropolymers

Yoshida, Masaru; Chen, J.; Asano, Masaharu; Maekawa, Yasunari; Yamamoto, Toshinori*; Kuroda, Shinichi*; Kubota, Hitoshi*

no journal, , 

The UV-induced photografting of styrene (St) on fluoropolymer films was investigated at 60$$^{circ}$$C in a mixture of water and organic solvents with a photoinitiator xanthone. From the results of the combination of the aliphatic ketones (acetone as an example) and water, it was discovered that the photografting of St happens on polytetrafluoroethylene (PTFE) film well-known as impossible up to now. To confirm whether the graft chains were introduced in the material, the PTFE-g-PSt membrane was sulfonated in 0.2M ClSO$$_{3}$$H solution, to evaluate the proton conductivity in the thickness direction. The proton conductivity was obtained to be 0.075 S/cm in a 5.3% degree of grafting, indicating that the UV grafting process is one of the effective methods to prepare the polymer electrolyte membranes.

Oral presentation

Preparation of anion-exchange membranes for fuel cell applications by $$gamma$$-ray pre-irradiation grafting; Effect of the structure of quaternary ammonium ions

Koshikawa, Hiroshi; Yamaki, Tetsuya; Asano, Masaharu; Yoshimura, Kimio; Maekawa, Yasunari; Yamamoto, Kazuya*; Shishitani, Hideyuki*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Tanaka, Hirohisa*

no journal, , 

We investigated the effect of the length of the linear chain on the structure of quaternary ammonium ions on the membrane properties such as durability of ion conductivity. Graft polymerization was performed by immersing the pre-irradiated ETFE film in the CMS solution. The ETFE-g-CMS film was then quaternized in four different tertiary amines, that is, trimethylamine (n = 1), dimethylethylamine (n = 2), n-butyldimethylamine (n = 4) and n-hexyldimethylamine (n = 6) solutions. The n dependence of the OH$$^{-}$$ conductivity and chemical durability, which was represented by a residual percentage of the conductivity after treatment with a Fenton solution. When n increased from 1 to 6, the OH$$^{-}$$ conductivity decreased slightly, but it still stayed 20 mS/cm for n = 6. The chemical durability seemed to increase eight-fold at the same time. The chemical attack by hydroxyl radicals on the quaternary ammonium ions would be controlled by hydrophobicity and steric hindrance of the alkyl group.

30 (Records 1-20 displayed on this page)