Morphological engineering of SiO₂ interlayer towards meliorative dielectric and thermal properties in β‐SiC_w@SiO₂/PVDF composites

Abstract Polymers with high thermal conductivity (TC) and dielectric constant (ε) but low dielectric loss show enormously potential applications in electrical power systems. To enhance the ε and TC while significantly suppressing the loss of β‐silicon carbide whisker (β‐SiC_w)/polyvinylidene fluoride (PVDF), in this study, SiO₂ shells with different morphologies were constructed on the superficies of β‐SiC_w via a facile oxidation method in air atmosphere. The SiO₂ shell’ morphology on the TC and dielectric performances of the β‐SiC_w@SiO₂/PVDF are systematically explored as a function of the frequency and filler loading. The β‐SiC_w@SiO₂/PVDF demonstrate astonishingly restricted loss and meliorative TC when compared to the β‐SiC_w/PVDF because the SiO₂ shell not only suppresses the β‐SiC_w from direct contact with one another and impedes the long‐distance charges migration thereby resulting in rather low loss and leakage conductivity, but also restrains the thermal interfacial resistance via increased interfacial compatibility and interactions. The concurrent enhancement effect in the ε and TC but low loss of the composites is more evident in the crystalline SiO₂ interlayer with a high TC compared with amorphous one. These results provide insight into the exploration of composite nanodielectrics with large TC and ε but low loss for applications in electrical power systems. Highlights Core@shell structured β‐SiC_w@SiO₂/PVDF were obtained by a facile oxidation. The great reduction in both loss and conductivity is attributed to the SiO₂ shell. Crystalline SiO₂ shell can improve the composites' thermal conductivity. The SiO₂ shell prevents long‐range carrier migration.