Insights into Synchronously Enhanced Dielectric Properties and Thermal Conductivity of β-SiCw/PVDF Nanocomposites by Building a Crystalline SiO2 Shell as an Interlayer

Polymeric nanocomposites possessing high dielectric constant (k) without an unacceptably large increase in dielectric loss (k″) and excellent thermal conductivity (TC) are extremely desirable in microelectronics. In this study, a crystalline SiO2 shell (silicon dioxide shell) was constructed on the surface of β-silicon carbide whiskers (β-SiCw, denoted as whisker-0) under air by high-temperature oxidation, and the obtained core–shell-structured β-SiCw@SiO2 whiskers (denoted as calcined whiskers) were composited with poly(vinylidene fluoride) (PVDF) to deliberately generate morphology-controllable high-k, low-loss, and high-TC nanocomposites. The results show that the calcined whisker/PVDF nanocomposites reveal extremely low k″ and conductivity in comparison to the whisker-0/PVDF analogues because the insulating SiO2 interlayer prevents direct contact among whisker-0 and therefore remarkably suppresses the long-range charge migration. In particular, both the loss and conductivity tend to regularly reduce with increasing thickness of the SiO2 shell while maintaining a high k. Simultaneously, the constructed crystalline SiO2 interlayer compatibilizes the whisker-0 filler with the PVDF matrix via hydrogen bonding while restraining the interfacial thermal resistance and facilitating phonon transport at interfaces, resulting in increased TC of the nanocomposites compared to amorphous SiO2-encapsulated whisker-0 counterparts. 50 wt % calcined whisker/PVDF nanocomposites have rather good dielectric performances such as a very low k″ of 0.08 (100 Hz) and a greatly improved TC of 2.41 W/m K, compared with 1957 and 2.1 W/m K for 50 wt % whisker-0/PVDF nanocomposites, respectively. The synchronous enhancement in both dielectric properties and TC makes the nanodielectrics show appealing prospective applications in microelectronic and electrical industries.