Towards suppressing loss tangent: Effect of SiO2 coating layer on dielectric properties of core-shell structure flaky Cu reinforced PVDF composites

Flaky Cu (f-Cu) particles coated with various thickness of silica (SiO2) were incorporated into poly(vinylidene fluoride) (PVDF) to investigate the effects of SiO2 coating layer and its thickness on dielectric properties of the composites. The morphological and dielectric properties of the composites were characterized. The results indicate that the SiO2 coating layer significantly affects the electrical properties of f-Cu@SiO2 and f-Cu@SiO2/PVDF, and that the PVDF composites with f-Cu@SiO2 particles exhibit superior dielectric properties compared with raw f-Cu. Dissipation factors (tanδ) of the f-Cu@SiO2/PVDF are remarkably suppressed and reduced to rather low level owing to the presence of SiO2 shell which serves as an interlayer between the f-Cu particles preventing them from contacting with each other. Furthermore, the effect of suppression on tanδ tends to be more prominent as the thickness of SiO2 coating layer increases. The as-prepared composites possess high dielectric constant and low tanδ, making them promising for the industrial application as embedded capacitors.