Spherical hybrid filler BN@Al2O3 via chemical adhesive for enhancing thermal conductivity and processability of silicon rubber

Abstract

AbstractHexagonal boron nitride (h‐BN) is an ideal candidate material for electrical and electronic systems due to its excellent performance. However, the addition of platelet‐like h‐BN leads to a dramatic increase of viscosity of composites and anisotropic thermal conductivity of composites. Herein, modified h‐BN (m‐BN) was coated onto spherical α‐Al2O3 via chemical adhesive, and core‐shell structured hybrid spherical filler (m‐BN@Al2O3) was prepared. Furthermore, the microstructure, rheology, mechanical properties, and thermal conductivity of hybrid filler/polydimethylsiloxane (PDMS) were studied. At 60 vol% filler loading, the thermal conductivity of m‐BN@Al2O3/PDMS is up to 2.23 W·m−1·K−1, which is 86% higher than that of Al2O3/PDMS and the ratio of in‐plane diffusivity to through‐plane diffusivity decreases from 2.0 to 1.0. At meanwhile, the viscosity of m‐BN@Al2O3/PDMS is about one fourth of the viscosity of m‐BN/Al2O3/PDMS. This simple and versatile strategy opens a pavement for enhancing the thermal conductivity of polymer and has great potential in high‐frequency communication.