Confined distribution of conductive particles in polyvinylidene fluoride-based multilayered dielectrics: Toward high permittivity and breakdown strength

Polyvinylidene fluoride (PVDF)-based multilayered dielectrics containing alternating layers of confined carbon black (CB) were fabricated using a layer-multiplying extrusion. For a given film thickness, a large enhancement of dielectric permittivity occurred following the increase of CB containing layers. When the number of total layers reached 256, the permittivity at 103 Hz became 3 times higher than that predicted by the series model. A frequency dependence in the dielectric loss curves caused by the layer multiplication process was also observed. The differences in capacitance and conductivity between neat PVDF and CB containing layers resulted in charge accumulation at their interfaces, leading to an increase in the permittivity and the dielectric loss peak intensity. Furthermore, the presence of PVDF between the CB containing layers distinctly improved the breakdown strength of the multilayered films by at least two orders of magnitude higher than that of the PVDF/CB conventional composite at a similar CB loading or conductivity level. The present approach for the preparation of high-k dielectrics with high breakdown strength would significantly broaden the choices of dielectric materials for pulse powered, high field electronics and a new generation of clean energy applications. (C) 2014 Elsevier Ltd. All rights reserved.