Dielectric thermally conductive boron nitride/silica@MWCNTs/polyvinylidene fluoride composites via a combined electrospinning and hot press method

With the development of microelectronics towards integration, miniaturization and high power, the accumulation of heat in this small space has become a serious problem. Therefore, polymer matrix composites with high thermal conductivity and electrical insulation need to be developed urgently. Here, an ordered oriented boron nitride/silicon dioxide (silica) coated multiwalled carbon nanotubes (BN/SiO₂@MWCNTs) thermally conductive network was constructed in a polyvinylidene fluoride (PVDF) matrix by electrostatic spinning technique, and subsequently the PVDF composites were prepared by hot-pressing. The synergistic effect of two-dimensional BN and one-dimensional MWCNTs in PVDF was investigated. It was found that the out-of-plane thermal conductivity of BN₃₀/SiO₂@MWCNTs composites reached 0.4693 Wm⁻¹ K⁻¹, which was 209% higher than that of pure PVDF and 10% higher than that of BN/PVDF composites. The in-plane thermal conductivity of BN₃₀/SiO₂@MWCNts) composites reached 1.5642 Wm⁻¹ K⁻¹, which was 1055% higher than pure PVDF and 40% higher than BN/PVDF composites. This is attributed to the synergistic effect of BN on SiO₂@MWCNTs. Meanwhile, the volume resistivity and breakdown strength of the BN/SiO₂@MWCNTs/PVDF composites reached 3.6 × 10¹³ Ω m and 47.68 kV/mm, respectively. The results indicate that the BN₃₀/SiO₂@MWCNTs/PVDF composites have excellent thermal conductivity and electrical insulating properties, which are promising for microelectronics applications.