Improved dielectric properties and thermal conductivity of PVDF composites filled with core–shell structured Cu@CuO particles

To suppress dielectric loss while still harvesting high dielectric constant (k) and thermal conductivity in polymer composites, core–shell structured fillers are synthesized via controlled calcination under air, where the conductive copper (Cu) particles are encapsulated by a thin insulating oxidation layer (CuO). The dielectric constant can be substantially improved in the poly(vinylidene fluoride) PVDF composites filled with Cu@CuO fillers, and the dielectric loss is strongly restrained even at high filler loadings. The improved dielectric performance can be ascribed to the insulating CuO shell, which promotes the multiple interfacial polarization and meanwhile impedes the long-range electron migration. Additionally, the Cu@CuO/PVDF composites exhibit higher thermal conductivity (TC) than the unfilled polymer and the Cu/PVDF, owing to the reduced interfacial thermal resistance between the fillers and the matrix. Composites with high TC and k but low loss are promising materials for potential applications in microelectronic, electrical and energy storage devices.