Excellent dielectric properties of Polyvinylidene fluoride composites based on sandwich structured MnO2/graphene nanosheets/MnO2

MnO2/graphene nanosheets/MnO2 (MGM) is fabricated by a facile and effective ethanol-assisted graphene-sacrifice reduction method. The morphology and structure of the MGM are examined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The MGM is used as a dielectric filler to prepare MGM/Polyvinylidene composites by solution casting and hot pressing. The MGM/Polyvinylidene composites exhibit excellent dielectric properties (dielectric constant is 2360, dielectric loss is 2.0) near the percolation threshold at 1 kHz which are better than that of most carbon/polymer composites. The excellent dielectric properties originate from the poor conductive MnO2 layers which not only ensure good dispersion of graphene nanosheets in the Polyvinylidene fluoride but also act as inter-particle barriers to prevent direct contact of the graphene nanosheets.