Enhancing through-plane thermal conductivity of epoxy-based composites via surface treatment of boron nitride cured with a flame retardant phosphazene-based curing agent

With rapid advances in electronic technology, efficient thermal dissipation and fire-retardant properties are being considered. However, the introduction of fire retardants degrades the thermal and mechanical properties because of the presence of many interfaces. In this study, we prepared a hexachlorocyclotriphosphazene–vanillin (PPNV)–NH2 curing agent via the Schiff base reaction to address these challenges. Boron nitride (BN) can be used for enhancing the thermal conductivity of composites, but shows poor dispersion in polymers. We treated the surface of BN with a mixture of thionyl chloride and chloroform, and furoic acid was subsequently attached to the BN surface to enhance the compatibility between the matrix and filler. A bisphenol A diglycidyl ether (DGEBA)/PPNV–NH2/F-BN composite with 50 wt% filler content was prepared and showed a through-plane thermal conductivity of 2.54 W/m·K and a tensile strength of 141 MPa. The prepared composite has good flame retardancy, which renders it suitable for thermal management applications.