▎ 摘　　要

Polymer matrix composites (PMCs) with high-k and low loss (tan delta) have aroused extensive research due to their significant applications in energy-storage capacitors and novel printed circuit board. In this work, the single layer structured graphene/polyvinylidene fluoride (GR/PVDF) composites were synthesized by hot pressing process, in which the fascinating permittivity transition from positive to negative was attributed to plasma oscillation. Meanwhile, the alternating current conductivity (sigma(ac)) and reactance behavior were well consistent with Jonscher's power law and equivalent circuit model. More importantly, the GR/PVDF composites consisted of negative-k layer that led to high-k and low tan delta performances. When the GR content of the negative-k layer was 10 wt% and positive-k layer was 2 wt%, the permittivity reached up to 559 and tan delta was just 0.053 at 100 kHz in bilayer structured composite, respectively. Theoretically, the high-k performance originated from strong interfacial polarization between positive-k and negative-k layers, which is beneficial to the synergistic effect of capacitive and inductive characters. Additionally, the low tan delta was attributed to the effectiveness restriction of electron transfer in capacitive layer. Therefore, the multilayer structured GR/PVDF composites by introducing negative-k layer can achieve high-k and low loss that supply a novel strategy for preparing dielectric materials. (C) 2021 Published by Elsevier Ltd.