The flexible metacomposites with tunable negative permittivity have great potential in wearable cloaks, stretchable sensors, and thin-film capacitors, etc. In this paper, the flexible graphene/polydimethyl­siloxane (GR/PDMS) metacomposites with tunable negative permittivity were prepared by an in situ polymerization method. The ac conductivity behavior, dielectric property, and impedance performance of the resulting composites with different graphene mass ratios (0–4 wt %) were studied. With the increase of graphene, the conductive mechanism of the resulting composites changed from hopping conduction to electron conduction, along with the change of microstructure. When graphene content in the composites came up to 3 wt %, the negative permittivity conforming to Drude model was observed. Further investigation revealed that there is a corresponding relationship between the permittivity and the reactance. It is demonstrated that the inductive character is responsible for the negative permittivity, while the capacitive character results in the positive permittivity.

The weakly negative permittivity behavior and its generation mechanism in flexible silver nanowires/carbon fiber felt metacomposites.

In this work, a hydrosoluble matrix is used for the first time to prepare flexible membranous composites, in order to improve their environmental friendliness and simplify the processing. Modified graphene (GR) sheets are distributed in polyvinyl alcohol (PVA) solution to achieve flexible GR/PVA metacomposites. As graphene content increases, an interconnected graphene network is eventually formed among the PVA matrix, and the resulting composites present a conductor‐like behavior. Interestingly, the Drude‐like negative permittivity is obtained in the composites with 20 wt% graphene, which is ascribed to the plasma oscillation. Meanwhile, the absolute values of negative permittivity decrease by several orders of magnitude due to the moderate electron density of graphene. It is demonstrated that the negative permittivity is dependent on the inductive character. This work provides a novel and versatile approach based on water‐soluble matrices to prepare flexible membranous metacomposites, which can be applied in wearable cloaking, thin‐film capacitors, and flexible and stretchable devices.

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