Anionic quaternary ammonium fluorous copolymers bearing thermo-responsive grafts for fuel cells

Fluorous copolymers are synthesized by grafting quaternary ammonium-functionalized 4-vinylbenzyl chloride (QVBC) and N-Isopropyl acrylamide (NIPAAM) from poly(vinylidene fluoride) (PVDF) via atom transfer radical polymerization (ATRP). Ionic PQVBC and thermo-responsive PNIPAAM grafts are characterized by proton nuclear magnetic resonance (1H NMR) spectroscopy. Polarity difference between flexible grafts and rigid fluorous backbones allows convenient formation of ionic clusters, which impart resultant membranes excellent hydroxide conductivities in the range of 21–52 mS cm−1 at 20 °C, and up to 98 mS cm−1 at 70 °C. Moreover, amide–amide interactions between thermo-responsive grafts at high temperature can mitigate water swelling of hydrophilic clusters. This study suggests that the fluorous copolymer bearing both ionic and thermo-responsive grafts holds a promising selectivity as novel materials for anion exchange membrane with enhanced hydroxide conductivity and controlled water swelling.