Graphene nanosheet-Fe3O4(GNS-Fe3O4) hybrids were obtained by a one-step solvothermal reduction of iron (III) acetylacetonate [Fe(acac)3] and graphene oxide (GO) simultaneously, which had several advantages: (1) the Fe3O4nanoparticles were firmly anchored on GNS surface even after mild ultrasonication; (2) the loading amount of Fe3O4nanoparticles could be effectively controlled by changing the initial feeding weight ratio of Fe(acac)3to GO; (3) the Fe3O4nanoparticles were homogeneously distributed on the GNS surface without much aggregation. Composites based on syndiotactic polystyrene (sPS) and GNS-Fe3O4were prepared by a solution-blending method and the electric and dielectric properties of the resultant GNS-Fe3O4/sPS composites were investigated. The percolation threshold of GNS-Fe3O4in the sPS matrix was determined to be 9.41 vol.%. Slightly above the percolation threshold with 9.59 vol.% of GNS-Fe3O4, the GNS-Fe3O4/sPS composite showed a high dielectric permittivity of 123 at 1000 Hz, which was 42 times higher than that of pure sPS. The AC electrical conductivity at 1000 Hz increased from 3.6 × 10-10S/m for pure sPS to 2.82 × 10-4S/m for GNS-Fe3O4/sPS composite containing 10.69 vol.% of GNS-Fe3O4, showing an obvious insulator-semiconductor transition.
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