▎ 摘　　要

NOVELTY - Fluorine-containing hyperbranched polyethylene copolymer, is claimed. The fluorine-containing hyperbranched polyethylene copolymer is prepared by one-step chain walking mechanism of ethylene and fluorine-containing monomer catalyzed by alpha-diimide palladium catalyst to obtain final product, where the fluorine-containing monomer is hexafluorobutyl acrylate, trifluoroethyl acrylate or tridecafluorooctyl acrylate. USE - The fluorine-containing hyperbranched polyethylene copolymer is useful in PVDF-based dielectric composite material (claimed). ADVANTAGE - The fluorine-containing hyperbranched polyethylene copolymer: performs functional modification on graphene, thus produces PVDF-based dielectric composite material with higher dielectric constant and low dielectric loss. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: (1) Preparing fluorine-containing hyperbranched polyethylene copolymer, comprising adding anhydrous solvent A, fluorine-containing monomer and alpha-diimide palladium catalyst into a dry reaction vessel in an ethylene atmosphere and mixing, stirring and reacting for 0.5-48 hours, carrying out separation and purification to obtain final product; (2) PVDF-based dielectric composite material, comprising (1) introducing graphite powder, fluorine-containing hyperbranched polyethylene copolymer and chloroform into container, subjecting to ultrasonic treatment for 24-144 hours after sealing, centrifuging the obtained suspension and allowing to stand for 0.5-2 hours, and taking the supernatant to obtain a graphene dispersion containing excess polymer; carrying out vacuum filtration to remove the free polymer to obtain graphene dispersion liquid containing excess copolymer, then ultrasonic wave makes it disperse in chloroform again, can repeat the vacuum filtration-ultrasonic dispersion step until a graphene organic dispersion without excess free fluorine-containing hyperbranched polyethylene copolymer is obtained, where the mass ratio of fluorine-containing hyperbranched polyethylene polymer concentration to graphite to be controlled at 0.25-1.5, preferably 0.25, and the graphite initial charging concentration is 1-9 mg/ml, the concentration of fluorine-containing hyperbranched polyethylene polymer is 1-6 mg/ml, (2) dissolving P(VDFTrFE-CFE) powder in N,N-dimethylformamide to obtain a P(VDFTrFE-CFE) solution, then adding the graphene organic dispersion obtained in step (1), stirring at 500-1000 revolutions/minute for 0.2-30 minutes to mix the solution to obtain a mixed solution, where the concentration of P(VDF-TrFE-CFE) solution to be controlled at 1-1500 mg/ml, and the mass ratio of graphene to P(VDF-TrFE-CFE) to be controlled at 0.1-10:100; (3) casting the mixed solution obtained in step (2) on the mold and drying to obtain a PVDF-based dielectric composite material.