PVDF composites filled with core–shell fillers of Si@SiO₂, Si@SiO₂@PS: effects of multiple shells on dielectric properties and thermal conductivity

Exploring polymer composites with a high dielectric constant (ε′) and breakdown strength (E_b), low dissipation factor (tanδ), as well as a high thermal conductivity (TC) is of crucially important thanks to their potential applications in modern electronics. Herein, in this paper, two kinds of core–shell-structured Si particles, i.e., Si@SiO₂, Si@SiO₂@PS, were prepared by high temperature oxidation and polystyrene (PS) coating and incorporated into PVDF (poly(vinylidene fluoride)). The results indicate that both the fillers’ kinds and loading have obvious influences on dielectric and thermal properties of the composites. The SiO₂ interlayer between the Si and PVDF matrix remarkably suppresses the loss and reduces leakage conductivity, whereas encapsulation of Si@SiO₂ with a PS shell further inhibits the loss and conductivity, and the organic PS interlayer enhances the interfacial compatibility and promotes the fillers’ homogeneous dispersion in PVDF, therefore improving the E_b of the composites. More importantly, the PVDF composites with 50 wt.% of Si@SiO₂@PS show good comprehensive performances: ε′ of 66.6 but tanδ of 0.04 at 100 Hz, E_b of 2.48 kV/mm as well as a high TC of 1.0 W/m K. The prepared Si@SiO₂@PS/PVDF composites show promising potential applications in microelectronics and electrical industries.