High-k Dual Crosslinkable Polymer Nanocomposite Dielectrics Based on P(MMA-co-HEMA)/BaTiO 3 for Film Capacitors

Abstract

Abstract In order to obtain high-quality photocrosslinkable polymer matrix, cinnamoyl chloride functionalized poly(methyl methacrylate-co-2-hydroxyethyl methacrylate) [f-P(MMA-co-HEMA)] was synthesized. The functionalization and photocrosslinking of the polymer were confirmed through FTIR, 1H NMR, and UV characterization. In order to obtain high-quality, flat and pinhole-free polymer films, the effects of different photocrosslinked processes on the polymer film quality were investigated. When the crosslinking time was 10 min and the crosslinking degree was 55%, the dielectric constant of the capacitor reached to 4.65, the dielectric loss was as low as 0.04, the dielectric strength was as high as 343 V/µm, and the maximum energy density was 2.4 J/cm3. In order to obtain composite materials with high dielectric constant, photocrosslinkable functionalized copolymer f-P(MMA-co-HEMA) was used as the polymer matrix, and surface modified BT with phosphoric acid was introduced through ball milling dispersion to prepare photocrosslinkable f-P(MMA-co-HEMA)/m-BT composite film. By surface and cross-sectional SEM characterization, BT was uniformly dispersed in the polymer matrix. FTIR confirmed that the C = C group on the surface modified BT disappeared after photocrosslinking, which formed chemical binding between the two phases in the nanocomposite material, and the composite material formed a double crosslinking network structure. When the BT content was 30 wt%, the dielectric constant reached up to 51. With the bending angle of the capacitor changed by 120֯, the capacitance value changed by 27%, indicative of good sensitivity.