Tunable negative permittivity in graphene/poly(vinylidene fluoride) composites with low percolation threshold

Meta-materials with fascinating dielectric behavior have drawn much attentions for their potential applications recently. Herein, percolating GR/PVDF composites consisting of GR sheets homogeneously dispersed in PVDF matrix are fabricated via hot-pressing method in 20 Hz-1 MHz frequency regions, of which simultaneously realizing negative permittivity with low percolation threshold. It’s demonstrated that negative permittivity of GR/PVDF composites are resulted from the low-frequency plasma oscillation of free electrons, and a universal regulatory mechanism of Drude model is analyzed. At the same time, rapid formative 3D GR conductive networks contributed to the low percolation threshold (7.78wt%) of composites. Moreover, it is shown that electrical percolation occurred in samples as GR content exceeds percolation threshold, indicating a typical metal-like behavior. In addition, the reactance is discussed according to the equivalent circuit analysis. This work constructed the meta-composites with low filler content, which is benefit for practical applications in electromagnetic devices. This article is protected by copyright. All rights reserved.