Tailoring dielectric performance of Ni/poly(vinylidene fluoride) composites through constructing NiO shell as an interlayer

An insulating interlayer between conductive filler and polymer matrix is essential for inhibiting the dielectric loss of polymer composites. To suppress the dielectric loss of nickel (Ni)/poly(vinylidene fluoride) (PVDF) composites while still having a high dielectric permittivity (k) near the percolation threshold, Ni particles were first encapsulated with a layer of insulating NiO shell through direct thermal oxidation method at high temperature, and then were incorporated into PVDF to explore the influence of the NiO coating on dielectric properties of the Ni/PVDF composites. The results indicate that the calcination temperature and the filler loading significantly influence the dielectric properties of the composites. Ni@NiO/PVDF composites have high k and low loss compared with the pristine Ni/PVDF. The NiO insulating interlayer prevents Ni particles from direct contact thereby leading to significantly suppressed conductivity and loss even at high filler loadings. Increasing shell thickness reduces dielectric loss with the k almost unaffected. These Ni@NiO/PVDF composites with a high k and very low loss show promising potential application in the microelectronic and electrical industries.