Preparation of branched Al2O3 and its synergistic effect with carbon nanotubes on the enhancement of thermal conductive and electrical insulation properties of silicone rubber composites

With the increasing demand for thermal management materials in the highly integrated electronics fields, it is great significant to develop next-generation thermal conductive yet electrically insulating composites to efficiently solve “hot spot” problems. Herein, based on sintering mass transfer of particles, branched Al 2 O 3 (B-Al 2 O 3 ) are prepared by calcinating spherical Al 2 O 3 , and then are introduced into silicon rubber (SiR) matrix with CNTs to fabricate SiR composites. The B-Al 2 O 3 fillers are overlapped with each other through branched structures, while CNTs with a high aspect ratio contribute to construct a more continuous thermal conductive network effectively by bridging B-Al 2 O 3 in the composites. The SiR composite exhibits a higher thermal conductivity of 1.307 W·m −1 ·K −1 with 20 vol% B-Al 2 O 3 and 0.5 wt% CNTs, which is also higher than that of SiR incorporated with 37 vol% B-Al 2 O 3 . Meanwhile, the electrically insulation of the SiR composites is not damaged due to the addition of a small amount of CNTs, which shows high volume resistivity of 10 15 Ω·cm. Furthermore, the SiR composites possess elevated flexibility, tensile strength , Young’s modulus and fracture toughness. Our findings provide a practical route to produce polymer composites with high thermal conductivity and excellent electrically insulation performance for thermal management applications in advanced electronic devices.