Copolymerization of α-Cyanovinyl Acetate with Acrylonitrile and Methacrylonitrile: Synthesis, Characterization, and Study of their Dielectric Behavior

In the frame of a research aiming at developing new dielectric polymers containing C-CN substituent with strong dipole moment, the radical copolymerization of cyano (nitrile) monomers and an alpha-cyanovinyl acetate (CVA) as the comonomer, initiated by AIBN is described. Methacrylonitrile (MAN) and acrylonitrile (AN) were chosen as the cyano monomers. The homopolymer of CVA was also prepared and the corresponding yield was close to 60%. All these polymers were characterized by C-13 NMR, IR, DSC, and TGA. The percentages of incorporation of AN and MAN in the copolymers were 36 and 56%, respectively. These products showed high glass transition temperatures, T-g, ranging between 124 and 142 degrees C. The thermogravimetry analyses showed that these copolymers are stable up to 200 degrees C. Dielectric spectroscopy analysis revealed a weak relaxation beta process below T-g. The alpha relaxation phenomena have also been characterized around the T-g and associated to the cooperative movements of the polar groups (CN). The values of dielectric relaxation increment were calculated at 150 degrees C using the Havriliak-Negami equation and indicated that these polymers exhibit interesting dielectric properties comparatively to similar cyano materials. The alpha-activation energies were also calculated. New statistic copolymers based on CVA were characterized. The values of the intensity of alpha relaxation show the potential application of such materials in the domain of electronics. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 1094-1104, 2009