Enhancement in electroactive crystalline phase and dielectric performance of novel PEG-graphene/PVDF composites

In this work, polyethylene glycol grafted graphene (PEG-graphene) was obtained from the amidation reaction between graphene oxide and methoxypolyethylene glycol amine followed by the NaHB ₄ reduction and characterized by transmission electron microscope, Fourier transform infrared spectroscope, wide-angle X-ray diffraction, Raman spectroscope, X-ray photoelectron spectroscope, and thermogravimetric analysis. The PEG-graphene was incorporated into polyvinylidene fluoride (PVDF) to form novel PEG-graphene/PVDF composites by the solution blending method. The well dispersion of PEG-graphene in the PEG-graphene/PVDF composite was confirmed by scanning electron microscopy. Based on the results of FTIR, WAXD, differential scanning calorimetry, and XPS, it was found that the presence of PEG-graphene effectively enhanced the electroactive crystalline content of PVDF from 24.6% for the pure PVDF to 90.5% for the PEG-graphene (15 wt.%)/PVDF composite by the interfacial interaction. Moreover, the PEG-graphene (10 wt.%)/PVDF composite near the percolation threshold possessed a much higher dielectric constant of 53.3 compared to the pure PVDF (8.2), and a relatively low dielectric loss of 0.265 at 1000 Hz.