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Electroactive materials are of great interest for high performance capacitive behavior due to their relaxed ferroelectric properties. In this work, we studied the dielectric properties of poly(vinylidene fluoride) (PVDF) grafted with polystyrene (PS) by electron beam radiation induced free radical graft copolymerization reaction in solution. The dielectric constant of polystyrene grafted PVDF copolymers reaches about 90 at 100 Hz at room temperature representing more than seven times increment compared with the pristine PVDF matrix. The dielectric loss of 0.005 at 1 KHz can be achieved. Correlation of the dielectric properties with the graft copolymerization reaction mechanism was discussed. This route represents one of the most effective techniques to synthesize potential graft copolymers with desirable dielectric properties in a wide frequency range for energy storage applications.

We report the graft copolymerization synthesis of novel high dielectric constant HEMA (2hydroxyethylmethacrylate)-graft-poly(vinylidene fluoride) (PVDF) copolymers for potential applications in high energy density capacitors. In the present study the graft copolymerization reaction was introduced by irradiation (electron beam) treatment of the PVDF polymer powder. The chemical changes in the PVDF polymers after HEMA grafting were monitored and the results were evaluated by FTIR, DSC, TGA and contact angle measurement. An analysis is presented on the effectiveness of this approach as a function of electron beam operating variables including radiation dose, reaction time, reaction temperature, monomer concentration and effect of solvent. The PHEMA-g-PVDF copolymers demonstrate improved dielectric properties such as high dielectric constant, lower leakage and low dielectric loss as compared to pristine PVDF. Correlation of dielectric properties with the graft copolymerization reaction mechanism was discussed.