Negative permittivity of reduced graphene oxide/polyvinylidene fluoride membranous composites adjusted by heat treatment

Flexible composites with negative permittivity have a very broad development prospect in flexible electronics and wearable devices. Currently, how to control the negative permittivity except for from their intrinsic properties of components is still a challenge. In this study, the negative permittivity and frequency dispersion were adjusted by changing the heat treatment temperature. Polyvinylidene fluoride (PVDF) was selected as the flexible matrix and reduced graphene oxide (rGO) as the functional filler to prepare rGO/PVDF membranous composites. The negative permittivity was observed in rGO/PVDF composites film, and the effect of heat treatment temperature on the negative permittivity was further studied. It indicated that a higher heat treatment temperature contributed to the formation of conductive network, so as to obtaining negative permittivity. When the molding temperature was 70 °C, the negative permittivity spectrum conformed to the Drude model was only observed in the composites with 35 wt% content of rGO. After the heat treatment temperature reached 180 °C, when the content of rGO decreased to 25 wt%, the composites film achieved negative permittivity (~ − 10), which had a low-frequency dispersion in the test frequency range. The negative permittivity of in composites can be regulated by adjusting the heat treatment temperature, which promotes the application and development of flexible metamaterials in underwater sensing and detection, etc.