Polymers with n-type nitroxide side groups: Synthesis and electrochemical characterization

•Electroactive polymers with n-type nitroxides were synthesized.•The polymers show redox-reactions between −1.3 and −1.8 V.•Redox-potentials are lower than currently reported nitroxides.•Methacrylamide-, styrene- and iso-butylene-polymers were synthesized.•Theoretical capacities of polymers between 80 and 130 mAh/g.

This article describes the synthesis and electrochemical characterization of electroactive functionalized polymers with n-type nitroxides. Electron-poor phenyl nitroxide radicals with substituents like trifluoromethyl-, fluorine- or nitro-groups constitute the basic structural motif. The monomers were synthesized employing thio-“click” chemistry and polymerized by free radical polymerization or cationic polymerization techniques. The electrochemical properties of the resulting polymeric materials were investigated by cyclicvoltammetry. The monomers and polymers show reversible redox-reactions between −0.9 and −1.4 V (vs. Ag/AgCl) as well as a good stability over several cycles. These phenyl nitroxide radicals represent an interesting group of redoxactive polymers with highly negative redox-potentials, which makes them interesting candidates for organic radical batteries.

Graphical abstractThe synthesis and electrochemical characterization of nitroxide-bearing polymers with electron-withdrawing substituents is described. Styrene- and methacrylamide-monomers were polymerized employing free-radical polymerization techniques and subsequently oxidized. iso-Butylene monomers were polymerized in their oxidized form via cationic polymerization. These polymers were tested with cyclic voltammetry for their redox-stability and potential. They revealed reversible redox-reactions at potentials of −1.28 V (vs. Fc/Fc+) and below.Figure optionsDownload full-size imageDownload as PowerPoint slide