Membranes Based on PVdF–HFP and Alkylammonium Protic Ionic Liquids: Thermal and Transport Properties

Abstract

Casting from a solution is used to obtain proton-conducting membranes based on a poly(vinylidenefluoride-co-hexafluoropropylene) copolymer doped with diethylammonium hydrogen sulfate and diethylammonium mesylate with different levels of doping. An IR spectroscopic study is performed, and the phase behavior of the obtained membranes, their thermal and electrochemical stability, and specific electrical conductivity are investigated. It is established that doping protic ionic liquids into PVdF-HFP copolymer reduces the degree of its crystallinity. It has been shown that all membranes are thermally stable up to 290–300°C, and their conductivity at 145°C varies from 1.6 to 10.4 mS cm–1, depending on the level of doping.