Bromide and Hydroxide Conductivity–Morphology Relationships in Polymerized Ionic Liquid Block Copolymers

Abstract

A polymerized ionic liquid (PIL) diblock copolymer, poly(MMA-b-MEBIm-Br), was synthesized at various compositions from an ionic liquid monomer, (1-[(2-methacryloyloxy)ethyl]-3-butylimidazolium bromide) (MEBIm-Br), and a nonionic monomer, methyl methacrylate (MMA), via the reverse addition–fragmentation chain transfer (RAFT) polymerization technique. A hydroxide-conducting PIL diblock copolymer, poly(MMA-b-MEBIm-OH), was also prepared via anion exchange metathesis of the bromide-conducting block copolymer. In a former study, the conductivity and morphology of the bromide- and hydroxide-conducting PIL diblock copolymer were examined at one fixed PIL composition: 17.3 mol %. In this study, additional PIL compositions of (6.6, 11.9, and 26.5 mol %) were explored to fully understand the previous unusual conductivity results. Both bromide and hydroxide conductivities were higher in the PIL block copolymer at PIL compositions of 11.9, 17.3, and 26.5 mol % compared to the PIL homopolymer under the same experiment...