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

Copolymers of diisopropyl-p-vinylbenzyl phosphonate (DIPVBP) and I-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(diisopropylp-vinylbenzyl phosphonate-co-1-vinylimidazole) by hydrolysis of the phosphonate groups, which exhibits higher proton conductivity (10(-1) S cm(-1) at 30 degrees C) than the homopolymer of poly(vinylbenzylphosphonic acid).