Morphological engineering of SiO2 interlayer towards meliorative dielectric and thermal properties in ss-SiCw@SiO2/PVDF composites

Polymers with high thermal conductivity (TC) and dielectric constant (epsilon) but low dielectric loss show enormously potential applications in electrical power systems. To enhance the epsilon and TC while significantly suppressing the loss of ss-silicon carbide whisker (ss-SiCw)/polyvinylidene fluoride (PVDF), in this study, SiO2 shells with different morphologies were constructed on the superficies of ss-SiCw via a facile oxidation method in air atmosphere. The SiO2 shell' morphology on the TC and dielectric performances of the ss-SiCw@SiO2/PVDF are systematically explored as a function of the frequency and filler loading. The ss-SiCw@SiO2/PVDF demonstrate astonishingly restricted loss and meliorative TC when compared to the ss-SiCw/PVDF because the SiO2 shell not only suppresses the ss-SiCw 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 epsilon 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 epsilon but low loss for applications in electrical power systems.