title: Anion conductive aromatic block copolymers containing diphenyl ether or sulfide groups for application to alkaline fuel cells.
abstract: A novel series of aromatic block copolymers composed of fluorinated phenylene and biphenylene groups and diphenyl ether (QPE-bl-5) or diphenyl sulfide (QPE-bl-6) groups as a scaffold for quaternized ammonium groups is reported. The block copolymers were synthesized via aromatic nucleophilic substitution polycondensation, chloromethylation, quaternization, and ion exchange reactions. The block copolymers were soluble in organic solvents and provided thin and bendable membranes by solution casting. The membranes exhibited well-developed phase-separated morphology based on the hydrophilic/hydrophobic block copolymer structure. The membranes exhibited mechanical stability as confirmed by DMA (dynamic mechanical analyses) and low gas and hydrazine permeability. The QPE-bl-5 membrane with the highest ion exchange capacity (IEC = 2.1 mequiv g(-1)) exhibited high hydroxide ion conductivity (62 mS cm(-1)) in water at 80 °C. A noble metal-free fuel cell was fabricated with the QPE-bl-5 as the membrane and electrode binder. The fuel cell operated with hydrazine as a fuel exhibited a maximum power density of 176 mW cm(-2) at a current density of 451 mA cm(-2).
authors.affiliation: Interdisciplinary Graduate School of Medicine and Engineering, ‡Fuel Cell Nanomaterials Center, and §Clean Energy Research Center, University of Yamanashi , 4 Takeda, Kofu 400-8510, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Yokota
authors.forename: Hideaki
authors.initials: H
authors.lastname: Ono
authors.forename: Junpei
authors.initials: J
authors.lastname: Miyake
authors.forename: Eriko
authors.initials: E
authors.lastname: Nishino
authors.forename: Koichiro
authors.initials: K
authors.lastname: Asazawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kenji
authors.initials: K
authors.lastname: Miyatake
keywords: alkaline fuel cells; anion conductive membranes; block copolymers; hydrazine; poly(arylene ether)