▎ 摘　　要

A novel ultra-high-k composite material comprising of polyvinyl alcohol (PVA) as a polymer matrix and vanadium pentoxide (V2O5) and graphene oxide (GO) as fillers have been developed successfully using colloidal processing technique. The PVA/V2O5 and PVA/V2O5/GO composites were characterized using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-vis spectroscopy (UV), X-ray diffraction (XRD), thermogravimetric analysis (TGA), polarized optical microscopy (POM), scanning electron microscopy (SEM) and atomic force microscopy (AFM). FTIR studies indicate the strong chemical interaction between GO and polymer matrix. SEM results confirm that GO was homogeneously dispersed within the polymer matrix. The dielectric measurements show that PVA/V2O5/GO composites exhibit ultra-high dielectric constant and low dielectric loss. The dielectric constant increases from (epsilon = 189.40, 50 Hz, 40 degrees C) for PVA/V2O5 (95/05 wt/wt) composites to (epsilon = 5610.76, 50 Hz, 50 degrees C) for PVA/V2O5/GO composites with 2.5 wt% GO loading and the dielectric loss increases from (tan delta = 3.76, 50 Hz, 80 degrees C) for PVA/V2O5 (95/05) composites to (tan delta = 9.77, 50 Hz, 150 degrees C) for PVA/V2O5/GO composites with 2.5 wt% GO loading. This study opens up the avenue to prepare novel graphene-based polymer composites having ultra-high dielectric constant and low dielectric loss and extends the application window of graphene based fillers. (C) 2016 Elsevier Ltd. All rights reserved.