One-pot synthesis of hexafluorobutyl acrylate hyperbranched copolymer for graphene/poly(vinylidenefluoride-trifluoroethylene- chlorofluoroethylene) dielectric composite.

Dielectric polymer film capacitor is rapidly emerging as next-generation energy storage for advanced engineering applications because of its lightweight, low cost, and processability. Further increasing energy density of polymer film with high charge-discharge efficiency is prevalent research spotlight. The filler/polymer composite with compatible interface is proved as an effective strategy to improve the energy storage capability of dielectric film. In this work, we designed hyperbranched hexafluorobutyl acrylate copolymer as miscible interface in graphene/fluoropolymer dielectric composite. A facile one-pot method was adopted to synthesize hyperbranched polyethylene grafted hexafluorobutyl acrylate (HBPE--HFBA) copolymer, which was adsorbed on surface of nanosheets by non-covalent interaction during exfoliation of natural graphite. The graphene/poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) composite was prepared by solution casting. The interfacial polarization is enhanced with the improved compatibility of composite that is due to the chemical similarity between hexafluorobutyl acrylate segments and fluoropolymer matrix. The energy density of 0.1 wt% nanocomposite achieves 5.0 J cmwith charge-discharge efficiency of 78.1% at 250 MV m. This work provides an optional route for non-covalent functionalization of graphene and the development of flexible polymer film capacitor with large energy storage capability.