Copolymerization of 1-Ethyl-3-vinylimidazolium Bis(trifluoromethylsulfonyl)imide via Initiated Chemical Vapor Deposition

We studied the copolymerization of an ionic liquid (1-ethyl-3-vinylimidazolium bis(trifluoromethylsulfonyl)imide ([EVIm][TESI])) with ethylene glycol diacrylate (EGDA) via initiated chemical vapor deposition to form polymerized ionic liquid (Pit) copolymer films. The copolymerization was carried out by placing droplets of [EVIm][TESI] in the reactor and introducing EGDA and tert-butyl peroxide initiator in the vapor phase. The heterogeneous films that formed at the surface of the liquid droplets were composed of a homopolymer PEGDA top layer that formed by the polymerization of adsorbed EGDA at the liquid-vapor interface and a poly([EVIm] [TFSI]-co-EGDA) copolymer bottom layer that formed by the copolymerization of [EVIm][TESI] with absorbed EGDA within the liquid. The copolymer layer contained a gradient composition with decreasing concentration of [EVIm][TESI]. We showed that the composition of the copolymer films can be controlled by tuning the reaction time and pressure. In addition, we demonstrated that the films can be formed on solid supports which could allow these materials to be used as separation membranes and catalyst supports.