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Journal Articles

Imidazolium-based anion exchange membranes for alkaline anion fuel cells; Elucidation of the morphology and the interplay between the morphology and properties

Zhao, Y.; Yoshimura, Kimio; Shishitani, Hideyuki*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Koizumi, Satoshi*; Szekely, N.*; Radulescu, A.*; Richter, D.*; Maekawa, Yasunari

Soft Matter, 12(5), p.1567 - 1578, 2016/02

 Times Cited Count:19 Percentile:16.66(Chemistry, Physical)

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

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:16 Percentile:35.36(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

Hierarchical structure-property relationships in graft-type fluorinated polymer electrolyte membranes using small- and ultrasmall-angle X-ray scattering analysis

Tran Duy, T.*; Sawada, Shinichi; Hasegawa, Shin; Yoshimura, Kimio; Oba, Yojiro*; Onuma, Masato*; Katsumura, Yosuke*; Maekawa, Yasunari

Macromolecules, 47(7), p.2373 - 2383, 2014/04

 Times Cited Count:16 Percentile:36.85(Polymer Science)

The hierarchical structures of graft-type ETFE-based polymer electrolyte membranes (ETFE-PEMs) were investigated using small- and ultrasmall-angle X-ray cattering experiments. The ETFE-PEMs with IECs $$<$$ 2.4 mmol/g possessed conducting graft domains around lamellar crystals, with a d-spacing of 21.8-29.1 nm, and oriented crystallites with short and long correlation distances of 218-320 and 903-1124 nm, respectively. The membranes with IECs $$>$$ 2.7 mmol/g showed a new phase of crystallite network domains with a d-range of 225-256 nm, indicating a phase transition from oriented crystallite to crystallite network structures in the IEC range of 2.4-2.7 mmol/g. Noted that for the ETFE-PEMs with high IECs higher conductivity at 30% RH and compatible tensile strengths at 100% RH and 80 $$^{circ}$$ C, compared with Nafion, originated from the well-interconnected ion channels around the crystallites and the remaining lamellar crystals and crystallites, respectively.

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:11 Percentile:55.6(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

Optical detection of organic hydrides with platinum-loaded tungsten trioxide

Yoshimura, Kimio; Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito

Journal of Physics and Chemistry of Solids, 73(5), p.696 - 698, 2012/05

 Times Cited Count:4 Percentile:76.86(Chemistry, Multidisciplinary)

Tungsten trioxide powder with loading 0.1wt% platinum (Pt/WO$$_{3}$$) was prepared for opticaldetection of organic hydrides such as cyclohexane, decalin by impregnation with PtCl$$_6^{2-}$$ and subsequent calcination in N$$_{2}$$ gas at 500$$^{circ}$$C. The SEM observation of Pt/WO$$_{3}$$ shows that the Pt particles with mean diameters of 80-100 nm were on the surface of the WO$$_{3}$$ powder. The Pt/WO$$_{3}$$ showed coloration for 13% cyclohexane at higher 100$$^{circ}$$C and for 1.3% cyclohexane at 200$$^{circ}$$C. The in-situ XRD results of the Pt/WO$$_{3}$$ in coloring/bleaching change indicate that the coloring of Pt/WO$$_{3}$$ was caused by transformation of WO$$_{3}$$ to tungsten bronze. The analysis of reacted gas demonstrates that Pt on WO$$_{3}$$ produces only hydrogen and benzene through dehydrogenation of cyclohexane over 100$$^{circ}$$C. It was founded that the Pt/WO$$_{3}$$ has potential of optical detection of organic hydrides by heating at higher 100$$^{circ}$$C.

Journal Articles

Synthesis of palladium nanoparticles in a ceramic matrix using radiation grafting method

Yoshimura, Kimio; Hakoda, Teruyuki; Sugimoto, Masaki; Yamamoto, Shunya; Yoshikawa, Masahito

Radiation Physics and Chemistry, 80(4), p.587 - 590, 2011/04

 Times Cited Count:1 Percentile:87.73(Chemistry, Physical)

no abstracts in English

Journal Articles

Dehydrogenation catalyst for optical organic-hydride detection

Yoshimura, Kimio; Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito

Applied Surface Science, 257(9), p.4428 - 4431, 2011/02

 Times Cited Count:5 Percentile:71.17(Chemistry, Physical)

no abstracts in English

Oral presentation

Pd-folded ceramic nano fiber synthesis by ion beam irradiation from precursor polymer

Sugimoto, Masaki; Yoshimura, Kimio; Idesaki, Akira; Yoshikawa, Masahito; Seki, Shu*

no journal, , 

no abstracts in English

Oral presentation

Synthesis and properties of metal-chelating polycarbosilane polymer prepared by radiation grafting

Yoshimura, Kimio; Sugimoto, Masaki; Yoshikawa, Masahito

no journal, , 

Polycarbosilane (PCS) polymer with the chelated nickel or palladium was synthesized by the radiation-graft polymerization method. It was found that radicals induced in PCS polymers by electron beam irradiation behave as the sites of graft reaction between PCS polymer and glycidyl methacrylate (GMA) and the degree of graft polymerization was observed to be in proportion to the absorbed dose. After the chelate group was produced in the polymer chain derived from GMA by the reaction with diethylenetriamine, nickel or palladium was introduced into the chelate groups by soaking the solutions of corresponding metal salts. The obtained PCS polymer with the chelated nickel or palladium was fired at 973 K or 1373 K to produce silicon carbide (SiC) ceramics containing nickel or palladium and physical characteristics were measured by XRD, SEM and EDS analysis. As the results, it was found that nickel or palladium is isolated as fine metal grains on the SiC ceramics, i. e., the nickel grains are dispersed with carbon and palladium grains are cohesive on the surface of SiC ceramics.

Oral presentation

Modification of Ag nanoparticles on SiO$$_{2}$$ substrate by ion irradiation

Kawaguchi, Kazuhiro; Yoshimura, Kimio; Yamamoto, Shunya; Yoshikawa, Masahito; Takahiro, Katsumi*

no journal, , 

no abstracts in English

Oral presentation

Polycarbosilane functionalization using quantum beam techniques

Yoshimura, Kimio; Sugimoto, Masaki; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Modification of Ag nanoparticles on SiO$$_{2}$$ substrate by ion irradiation

Kawaguchi, Kazuhiro; Takahiro, Katsumi*; Yoshimura, Kimio; Yamamoto, Shunya; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Synthesis of metal containing ceramic nano-fiber by single particle nanofabrication technique, 2

Sugimoto, Masaki; Yoshimura, Kimio; Idesaki, Akira; Yoshikawa, Masahito; Asano, Atsushi*; Seki, Shu*

no journal, , 

no abstracts in English

Oral presentation

Synthesis of functional polycarbosilane nanofiber by ion beam induced radical polymerization

Yoshimura, Kimio; Sugimoto, Masaki; Idesaki, Akira; Yoshikawa, Masahito; Tsukuda, Satoshi*; Seki, Shu*

no journal, , 

no abstracts in English

Oral presentation

Synthesis of catalytic metal-chelating polycarbosilane polymer prepared by radiation grafting

Yoshimura, Kimio; Hakoda, Teruyuki; Sugimoto, Masaki; Yamamoto, Shunya; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Reduction activity of transition metal and nitrogen doped carbon films prepared by pulsed laser deposition

Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro; Yoshimura, Kimio; Yamaki, Tetsuya; Kobayashi, Tomohiro*; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Irradiation-induced change in optical absorption spectra of Ag and Au nanoparticles on SiO$$_{2}$$ substrate

Kawaguchi, Kazuhiro; Takahiro, Katsumi*; Yamamoto, Shunya; Hakoda, Teruyuki; Yoshimura, Kimio; Yoshikawa, Masahito

no journal, , 

no abstracts in English

Oral presentation

Dehydrogenation catalysts for optical organic-hydride detection

Yoshimura, Kimio; Hakoda, Teruyuki; Yamamoto, Shunya; Yoshikawa, Masahito

no journal, , 

no abstracts in English

49 (Records 1-20 displayed on this page)