▎ 摘　　要

In order to enhance the dispersion of graphene (Gra) in PVDF matrix and improve the interface properties of the composite materials, a copolymer (P[MMA-IL]) with 1-vinyl-3-ethyl imidazole bromine (IL) and methyl methacrylate (MMA) was synthesized by radical polymerization. A series of PVDF/PMMA, PVDF/PMMA/Gra, PVDF/P[MMA-IL] and PVDF/P[MMA-IL]/Gra were prepared using a solution-cast and hot pressing method. The morphological structure, crystallization and dielectric behavior were investigated by Raman spectrometer, field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), polarized optical microscopy (POM), differential scanning calorimetry (DSC) and LCR meter, respectively. Raman spectra indicated that strong pi interaction between imidazole ring and carbon ring established between P[MMA-IL] and Gra, and FESEM observation showed the good dispersity of Gra in PVDF matrix due to that interaction. DSC results indicated that, TT of PVDF was decreased by the presence of PMMA as a diluent, and that T-c and T-m of PVDF were promoted by P[MMA-IL] modified Gra because of the presence of beta polar crystal. Gra was modified by P[MMA-IL] as a template to increase the degree of crystallinity of PVDF. XRD and FTIR-ATR results confirmed that the beta-crystal was not induced by PMMA and Gra, but by P[MMA-IL] due to the electrostatic interaction between the > CF2 of the polymer backbone and imidazolium cation, and the strong induction was brought by the template of Gra. POM photos displayed that alpha-crystal with loose structure were embedded into the chip space of spherulites because the presence of MMA chain segments. The electrostatic interaction and nucleating agents of IL chain segments resulted in beta crystal with small size and increased the crystallization rate. Dielectric properties study showed that PMMA and modified Gra reduced the crystallinity and concentration of PVDF chain, leading to weak interface polarization and orientation polarization of PVDF. The dielectric constant is low. While P[MMA-IL] and modified Gra induced more beta crystal, the strong interface polarization was enhanced by beta crystal and ion polarization of IL chain segments improved the dielectric constant.