Star poly(ionic liquid)s: Chain architecture‐property relationships

Abstract In this study, we report the synthesis of 3‐, 4‐, and 6‐arm star poly(ionic liquid)s (PILs) (specifically, star poly(vinylbenzyl methylimidazolium bis(trifluoromethane)sulfonimide) (poly(VBMIm‐TFSI))) via reversible addition‐fragmentation chain transfer (RAFT) polymerization with a core‐first approach, followed by quaternization and anion exchange. The impact of star polymer architecture on properties was explored by measuring the thermal, mechanical, and ion transport properties of each star PIL compared to those of an analogous linear PIL. The star PILs exhibited up to 2‐fold higher ionic conductivity, 150% higher elastic modulus, and 465% higher ultimate tensile strength compared to the analogous linear PIL. The Williams‐Landel‐Ferry (WLF) equation was employed to explore the effect of increased free volume on the improved ion transport properties of the star PILs. These results highlight the impact of star polymer architecture on PILs and star PILs as promising materials for electrochemical energy devices.