Novel Method for the Fabrication of Flexible Film with Oriented Arrays of Graphene in Poly(vinylidene fluoride-<i>co</i>-hexafluoropropylene) with Low Dielectric Loss

Carbon–polymer nanocomposites with good dielectric properties have potential applications in the electronic and electrical industry because of their good mechanical properties and low cost. The morphology, structure, dielectric properties, and mechanical strength of reduced-graphene oxide nanosheet/poly(vinylidene fluoride-co-hexafluoropropylene) nanocomposites (rGO/PVDF-HFP) were investigated. The rGO nanosheets were well dispersed and strongly oriented in the matrix, thanks to the unique spin-assistant preparation process. A dielectric constant of 54 (100 Hz) which was four times higher than that of pure PVDF-HFP was obtained when the concentration of rGO was 0.7 vol % and the dielectric loss was as low as 0.27. The good dielectric performance of the nanocomposites was attributed to the homogeneous dispersion and good alignment of rGO. The shear force provided by spin-coating, the thickness decreasing process, and thickness control were assumed to be key factors in the alignment of rGO nanosheets in the nanocomposite films. At the same time, the aligned rGO sheets increased the percolation threshold of the composite which shed light on the mechanism for obtaining low loss materials.