title: N-Spirocyclic Quaternary Ammonium Ionenes for Anion-Exchange Membranes.
abstract: The development of cationic polymers for anion-exchange membranes (AEMs) with high alkaline stability and conductivity is a considerable challenge in materials chemistry. In response, we here present the synthesis and properties of N-spirocyclic quaternary ammonium ionenes (spiro-ionenes) containing 5- and 6-membered rings fused by central nitrogen cations. High-molecular weight and film-forming spiro-ionenes are successfully synthesized in cyclo-polycondensations of tetrakis(bromomethyl)benzene and dipiperidines under mild conditions. These polyelectrolytes show excellent thermal and alkaline stability with no degradation detected by NMR spectroscopy after more than 1800 h in 1 M KOD/D2O at 80 °C. Even at 120 °C, the spiro-ionenes display reasonable alkaline stability. Transparent and mechanically robust AEMs based on ionically cross-linked blends of spiro-ionene and polybenzimidazole reach OH-conductivities up to 0.12 S cm-1at 90 °C. The current findings demonstrate that spiro-ionenes constitute a new class of alkali-stable anion-exchange polymers and membranes.
authors.affiliation: Polymer & Materials Chemistry, Department of Chemistry, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Thanh Huong
authors.initials: TH
authors.lastname: Pham
authors.affiliation: Polymer & Materials Chemistry, Department of Chemistry, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Joel S
authors.initials: JS
authors.lastname: Olsson
authors.affiliation: Polymer & Materials Chemistry, Department of Chemistry, Lund University , P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Patric
authors.identifier: 0000-0002-1102-3959
authors.initials: P
authors.lastname: Jannasch