Enhanced electroactive phase, toughness and dielectric properties of poly(vinylidene fluoride) with addition of MMA-BA-IL copolymer

Abstract

Methyl methacrylate (MMA), butyl acrylate (BA) and 1-butyl-3-vinylimdazolium tetrafluoroborate ([BVIM][BF4]) copolymer (MMA-BA-IL) was prepared and used to enhance the electroactive phase content, toughness and dielectric properties of poly(vinylidene fluoride) (PVDF). Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) tests indicated that crystal transformation of PVDF from α-phase to β/γ-phase occurred due to ion-dipole interaction between PVDF and [BVIM][BF4]. Scanning electron microscope (SEM) results showed MMA-BA-IL copolymer dispersed in the PVDF uniformly and the partial replacement of MMA components by [BVIM][BF4] decreased the miscibility between PVDF and MMA-BA copolymer. MMA-BA-IL copolymer improved the tensile ductility and impact toughness of PVDF. When the content of MMA-BA-IL was beyond 10 wt%, the elongation at break was higher than 400% and the impact strength was higher than 600 J/m. Deformation mechanism researches proved that shear yielding of the PVDF matrix and debonding/cavitation of the MMA-BA-IL copolymer particles were the major toughening mechanisms. The addition of MMA-BA-IL copolymer enhanced the dielectric properties of PVDF significantly. When the MMA-BA-IL content was 15 wt%, the dielectric constant of the PVDF/MMA-BA-IL blend increased to 54.3 at the 100 Hz frequency, which improved by 246% relative to that of the pure PVDF.