title: Dispersion of Rod-like Particles of Nafion in Salt-Free Water/1-Propanol and Water/Ethanol Solutions.
abstract: The dispersion of perfluorinated sulfonic acid ionomers in catalyst inks is an important factor controlling the performance of catalyst layers in membrane electrode assemblies of proton exchange membrane fuel cells (PEMFCs). The effect of water/alcohol composition on the dispersion of H-Nafion in water/1-propanol and water/ethanol solutions was studied by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and (19)F nuclear magnetic resonance ((19)F NMR) spectroscopy. Hydrodynamic radii calculated from DLS decay profiles and the radii and interparticle distance of rod-like particles derived from SAXS profiles showed almost the same dependence on alcohol concentration. 1-Propanol was more effective than ethanol to induce changes in the characteristic lengths of the rod-like particles. The motional narrowing in the (19)F NMR spectra by addition of 1-propanol indicates selective solvation of the rod-like particles. We suppose this might have decreased their radii and induced their elongation, which eventually led to extension of the ordered regions as observed in the hydrodynamic radii. Our study helps to clarify the dispersion of Nafion in aqueous alcohol solutions, which has implications for the performance of PEMFCs.
authors.affiliation: Fuel Cell Cutting-edge Research Center (FC-Cubic), Technology Research Association , AIST Tokyo Waterfront Main Building, 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Toyota Central R&D Laboratories , Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Takuro
authors.initials: T
authors.lastname: Matsunaga
authors.affiliation: Higashifuji Technical Center, Toyota Motor Corporation , 1200 Mishuku, Susono, Shizuoka 410-1193, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Amemiya
authors.affiliation: Fuel Cell Cutting-edge Research Center (FC-Cubic), Technology Research Association , AIST Tokyo Waterfront Main Building, 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan.|Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST) , 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohira
authors.affiliation: Toyota Central R&D Laboratories , Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hasegawa
authors.affiliation: Fuel Cell Cutting-edge Research Center (FC-Cubic), Technology Research Association , AIST Tokyo Waterfront Main Building, 2-3-26 Aomi, Koto-ku, Tokyo 135-0064, Japan.|Nissan Research Center, Nissan Motor Company, Limited , 1 Natsushima-cho, Yokosuka, Kanagawa 237-8523, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shinohara
authors.affiliation: Higashifuji Technical Center, Toyota Motor Corporation , 1200 Mishuku, Susono, Shizuoka 410-1193, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ando
authors.affiliation: Higashifuji Technical Center, Toyota Motor Corporation , 1200 Mishuku, Susono, Shizuoka 410-1193, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Yoshida