The improved interfacial polarization in a poly(vinylidene fluoride-co-chlorotrifluoroethylene) composite with hyperbranched polyethylene-graft-poly(methyl methacrylate) modified boron nitride nanosheets

Abstract

Polymer capacitors are promising candidates for the miniaturization and integration of electronic devices due to their flexibility and large power density. The current energy storage performance of polymer dielectrics is still not sufficient to meet the rapid development of up-to-date electronic technology. Here, we designed a compatible poly(methyl methacrylate) (PMMA) interface with a poly(vinylidene fluoride-co-chlorotrifluoroethylene) P(VDF-CTFE) nanocomposite incorporated with boron nitride nanosheets (BNNSs) to improve the electrical energy capability. The BNNS/P(VDF-CTFE) nanocomposite film was prepared via a solution casting method. The rigid PMMA segments in the hyperbranched polyethylene-graft-poly(methyl methacrylate) (HBPE-g-PMMA) copolymer establish an improved compatibility between the BNNSs and fluoropolymer that restricts the motion of charge carriers, which results in an enhanced interfacial polarization. The stable BNNS dispersion was exfoliated by a liquid-phase preparation with the assistance of the HBPE-g-PMMA copolymer, which was adsorbed on the nanosheets via non-covalent CH–π interactions and served as steric hindrance against aggregation. Consequently, the energy density of the 0.5 wt% nanocomposite achieved 6.6 J cm⁻³ with a charge–discharge efficiency of 51.5% at 400 MV m⁻¹. This work delivers a universal strategy for the simultaneous exfoliation and functionalization of nanosheets to enhance the energy density of polymer nanocomposites that possess potential prospects for film capacitors.