Highly thermally conductive polymer-based composites with 3D exfoliated BNNS/functionalized SiC networks prepared by rapid solidification and hot pressing

High thermal conductivity polymer-based packaging materials can achieve effective heat diffusion, which is of great significance for the performance and longevity of electronic devices. Exfoliated boron nitride nanosheets (s-BNNS) containing smaller particle sizes, fewer layers, and more hydroxyl groups were prepared by ball milling and strong ultrasonic treatment in this work. The functionalized SiC (m-SiC) was obtained by ternary blend organic silanol modification, which promoted the compatibility between fillers and fillers, as well as fillers and matrix. By a facile strategy of rapid solidification and hot pressing, s-BNNS were distributed between and on the surface of m-SiC fillers to form m-SiC/s-BNNS/polyamide 6/polyethylene terephthalate (PA6/PET) composite films with 3D thermally conductive networks. The thermal conductivity of m-SiC/s-BNNS/PA6/PET composite reached a superior 6.98 W/(m·K) at a filler loading 85 wt%, which was 124.67% higher than that of SiC/PA6/PET composite without 3D thermal network formation. More interestingly, reverse non-equilibrium molecular dynamics (RNEMD) simulations show that the hybrid SiC/BNNS filler greatly reduces the porosity within the composite compared to only one kind of filler, which in turn improves the composite's thermal conductivity.