Polymer-composite with high dielectric constant and enhanced absorption properties based on graphene–CuS nanocomposites and polyvinylidene fluoride

Novel reduced graphene oxide (RGO)/CuS nanocomposites, featuring CuS microspheres embedded in reduced graphene oxide (RGO) layers, are successfully fabricated by using an in situ growth approach in the presence of cexadecyl trimethyl ammonium bromide (CTAB) under mild wet-chemical conditions (140 °C). Characterization of the nanocomposites indicates that the CuS complex microspheres with relatively uniform size are embedded in the RGO layers to form unique core–shell nanostructures. A simple hot-press process is employed to synthesize the RGO/CuS/PVDF composites. With a filler loading of 15 wt%, the dielectric constant of the composites can reach 36 at 2 GHz, which is 10 times higher than that of pure PVDF. The composites with a filler loading of 5 wt% exhibit high values of reflection loss and the maximum loss is 32.7 dB at 10.7 GHz when the thickness is just 2.5 mm, and it can be adjusted by the thickness. The enhanced mechanism is also explained based on the Debye dipolar relaxation of the composites. The composite with a high dielectric constant is a promising material in high capacitance, while the composite with enhanced absorption can decrease the environmental pollution caused by microwave irradiation.