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Chen, J.; Asano, Masaharu; Maekawa, Yasunari
no journal, ,
Electrodialysis is an electrochemical process mainly used for the isolation and concentration of ionic species from aqueous solution. In this study, we develop radiation grafting polymeric ion exchange membranes for application in electrodialysis to remove metal ions in water. Two monomers of styrene derivatives, ethyl styrenesulfonate (ETSS) and chloromethyl styrene (CMS), were grafted onto poly(ethylene-co-tetrafluoroethylene) (ETFE) films by the radiation induced graft polymerization. The ETSS- and CMS-grafted films were easily converted into cation and anion exchange membranes, respectively. The resultant membranes showed similar range of ion exchange capacity (IEC), but the conductivity of the cation exchange membranes was higher than that of the anion exchange membranes with the same IEC level. Furthermore, the membranes with high IEC got the high electrodialysis speed, while those with low IEC had the high removal percent.
Fukasawa, Hideyuki*; Hasegawa, Shin; Maekawa, Yasunari
no journal, ,
The development of polymer electrolyte membranes (PEMs) with high proton conductivity at low relative humidity (RH) and excellent mechanical properties at high RH were required for commercialization of fuel cells. We previously reported the successful preparation of highly conducting and mechanically stable graft-type PEMs based on an aromatic hydrocarbon polymer, poly(ether ether ketone) (PEEK). On the other hand, polymer membranes are reinforced mechanically by the hybridization with inorganic nanoparticles. Therefore we investigated the radiation-induced graft polymerization of ethyl p-styrenesulfonate onto hybrid films consisting of PEEK and inorganic nanoparticles such as silica, magnesium oxide and aluminum oxide, and the effects of inorganic nanoparticles on the proton conductivity and durability of the obtained graft-type hybrid-PEEK PEMs.
Sekine, Yurina; Tojima, Yu*; Fukazawa, Tomoko*; Fukazawa, Hiroshi
no journal, ,
Hydrogels are unique materials that can contain a large amount of water in their three-dimensional polymer chain networks. Because of characteristic properties of water, hydrogels are widely used as biomedical materials. The structure of water is thus an important factor governing the chemical and physical properties of hydrogel materials. In order to investigate the effects of the side groups of polymer on the water structure, we measured the Raman spectra of polyacrylamide and poly-N,N-dimethylacrylamide hydrogels with various water contents. The results indicate that the water structure in the hydrogels depends on the structure of the side groups in the polymer chains.
Yamaguchi, Daisuke; Miyamoto, Nobuyoshi*; Nakato, Teruyuki*; Koizumi, Satoshi*; Ota, Noboru*; Yagi, Naoto*; Hashimoto, Takeji; Kawakatsu, Toshihiro
no journal, ,
Self-assembled structures of aqueous colloidal dispersions of niobate nanosheets having a uniform thickness of d = 1.6 nm and an average lateral dimension of L = 650 nm, hence an extremely large nominal aspect ratio (L/d) of 
400 were studied by micro-beam synchrotron small-angle X-ray scattering (SAXS). The results elucidated highly orientated, periodic layered liquid crystalline phase exhibiting a multiple-order scattering peaks. The line-profiles of the multiple-order peaks were analyzed in the directions both parallel and perpendicular to the one-dimensional stacks of the nanosheets for each order of the peaks. The results were compared with the formula based on harmonic approximation. An experimental problem associated with effects of orientation distributions of the stacks on the line profile analyses was quantitatively examined.
Yoshimura, Kimio; Zhao, Y.; Koshikawa, Hiroshi; Yamaki, Tetsuya; Shishitani, Hideyuki*; Yamaguchi, Susumu*; Tanaka, Hirohisa*; Koizumi, Satoshi*; Maekawa, Yasunari
no journal, ,
Anion conducting polymer electrolyte membranes (AEMs) having poly 2-methyl-1-vinylimidazolium grafts were synthesized by radiation-induced graft coplymerizaiton of 2-methyl-1-vinylimidazole with styrene onto an ETFE film, followed by N-alkylation and ion exchange reactions. The excellent long-term stability of the prepared AEMs was confirmed in 1M KOH at 80
C. The graft-type AEM with an ion exchange capacity of 1.80 mmol/g showed a maximum power density of 210 mW cm
in a direct hydrazine hydrate fuel cell test. The contrast variation experiment in small-angle neutron scattering measurement displayed the advantageous three-phase structures, consisting of crystalline, amorphous hydrophobic, and amorphous hydrophilic domains.