Proton-Conducting Polymers via Free Radical Polymerization of Diisopropyl-p-vinylbenzyl Phosphonate and 1-Vinylimidazole

Copolymers of diisopropyl- p -vinylbenzyl phosphonate (DIPVBP) and 1-vinylimidazole (1VI) prepared by free radical polymerization were studied. It was found that 1-vinylimidazole can be polymerized with DIPVBP. The reactivity ratios of 1VI and DIPVBP obtained from Kelen−Tudos plots were 0.10 ( r 1: 1VI) and 3.10 ( r 2: DIPVBP), respectively. According to the reactivity ratios, it is presumed that the imidazole moiety is surrounded by the phosphonate groups in the early stage of the copolymerization. A proton-conducting copolymer of vinylbenzylphosphonic acid and 1-vinylimidazole (P(VBPA- co -1VI)) was then obtained from poly(diisopropyl- p -vinylbenzyl phosphonate- co -1-vinylimidazole) by hydrolysis of the phosphonate groups, which exhibits higher proton conductivity (10 −1 S cm −1 at 30 °C) than the homopolymer of poly(vinylbenzylphosphonic acid).