Synchronous enhancements in dielectric performances and thermal conductivity of β-SiCw/PVDF nanocomposites through building crystalline SiO2 shell as an interlayer

Polymer composites with high dielectric permittivity (ε′), low dissipation factor (tanδ) and excellent thermal conductivity (TC) are extremely desirable in microelectronics. In this study, a crystalline silicon dioxide (SiO2) shell was constructed on the surface of β-silicon carbide (β-SiCw) whisker via a facile thermal oxidation method, and the obtained core@shell structured β-SiCw@SiO2 were composited with poly(vinylidene fluoride) (PVDF) to expect high-ε' and TC, but low loss nanocomposites. The results show that the β-SiCw@SiO2/PVDF nanocomposites display extremely low conductivity and tanδ compared to the raw β-SiCw/PVDF because the insulating SiO2 interlayer stops immediate contact among β-SiCw and remarkably suppresses the long-range charge migration. Moreover, both the dielectric loss and conductivity are further reduced with increasing the SiO2 shell’ thickness while still holding a high-ε′. The constructed crystalline SiO2 interlayer not only improves the interfacial compatibility between the PVDF and β-SiCw via hydrogen bonding, thereby restraining the thermal interfacial resistance and facilitating phonon transport, but also enhances the TC of the nanocomposites thanks to its much higher TC compared with amorphous SiO2 encapsulated β-SiCw. The 40 wt% β-SiCw@SiO2/PVDF have good overall properties such as a high-ε′ of 38 but a low tanδ of 0.07 (100 Hz), and a TC of 1.72 W/(m·K). Therefore, the synchronous enhancements in dielectric properties and TC make the β-SiCw@SiO2/PVDF nanocomposites exhibit appealing potential application in electrical and microelectronic industries.