title: Temperature- and humidity-controlled SAXS analysis of proton-conductive ionomer membranes for fuel cells.
abstract: We report herein temperature- and humidity-controlled small-angle X-ray scattering (SAXS) analyses of proton-conductive ionomer membranes. The morphological changes of perfluorosulfonic acid polymers (Nafion and Aquivion) and sulfonated aromatic block copolymers (SPE-bl-1 and SPK-bl-1) were investigated and compared under conditions relevant to fuel cell operation. For the perfluorinated ionomer membranes, water molecules were preferentially incorporated into ionic clusters, resulting in phase separation and formation of ion channels. In contrast, for the aromatic ionomer membranes, wetting led to randomization of the ionic clusters. The results describe the differences in the proton-conducting behavior between the fluorinated and nonfluorinated ionomer membranes, and their dependence on the humidity.
authors.affiliation: Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4 Takeda, Kofu, Yamanashi 400-8510 (Japan).
authors.forename: Takashi
authors.initials: T
authors.lastname: Mochizuki
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Kakinuma
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchida
authors.forename: Shigehito
authors.initials: S
authors.lastname: Deki
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kenji
authors.initials: K
authors.lastname: Miyatake
mesh_terms: D011211:Electric Power Supplies; D005465:Fluorocarbon Polymers / Q000737:chemistry*; D006813:Humidity; D008567:Membranes, Artificial; D011522:Protons; D053838:Scattering, Small Angle; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D005465:Fluorocarbon Polymers; D008567:Membranes, Artificial; D011522:Protons; C040402:perfluorosulfonic acid
keywords: block copolymers; fuel cells; membranes; phase separation; small-angle X-ray scattering