A molecular mechanics study on conformations of piezoelectric copolymers of vinylidene cyanide

Abstract A molecular mechanics calculation has been applied to investigate conformational characteristics of highly alternating copolymers of vinylidene cyanide with vinyl acetate and methyl methacrylate. The former shows high piezoelectricity, while the latter has quite low piezoelectricity. It was found that the main-chain conformations depend on the configurations of the main chain as well as the conformations of the side chains. Both copolymers were found to take trans -rich conformations around the C(CN) 2 CH 2 bond. The vinyl acetate copolymer takes predominantly the trans conformation around the CH 2 CH(OCOCH 3 ) bond. The methyl methacrylate copolymer also takes the trans -rich conformation around the CH 2 C(COOCH 3 )(CH 3 ) bond, but the fraction of trans conformer is not larger than that around the corresponding bond in the vinyl acetate copolymer. It was suggested that the main-chain conformation of vinylidene cyanide copolymers before drawing/poling treatments is one possible important factor determining the piezoelectric activity of these copolymers.