To investigate the effects of surface functionalization of exfoliated graphene (EG) on the crystalline form of ?-phase and dielectric properties of poly(vinylidene fluoride) (PVDF), we prepared PVDF-based composites reinforced by different functionalized EG. The X-ray photoelectron spectroscopy results indicated that a wide variety of chemical functional groups such as C?OH, C?O?C, C=O, COOH and C?F could be introduced on the surface of modified EG. As confirmed by results of Fourier transform infrared spectrum and X-ray diffraction, the ?-phase PVDF can be produced in the composites with the incorporation of functionalized EG. In the frequency ranging from 102 to 107 Hz, the dielectric permittivity of PVDF composites shows an obvious increase owing to a variation of the carbonyl group (C=O) content. Among all the composites, the EG grafted with polymethyl methacrylate/PVDF composite has the highest dielectric permittivity and dielectric loss.
