Multi-functional interface tailoring for enhancing thermal conductivity, flame retardancy and dynamic mechanical property of epoxy/Al₂O₃ composites

Interfacial tailoring is always the key to preparing high-performance polymer-based thermal conductive composites (PTCs). Herein, we reported a multi-functional interface tailoring approach to simultaneously improve the thermal conductivity, flame retardancy, thermal and mechanical properties of PTCs, by forming a core-shell structured graphene oxide coating Al₂O₃ hybrid (Al₂O₃@HGO). Simultaneously a flame retardant bridging agent was introduced to improve the coating amount and flame retardant efficiency of the hybrid. The morphology analysis revealed the significant reinforcement of interfacial interaction of Al₂O₃ in epoxy (EP) by HGO coating. As a result, such the interfacial tailoring induced both the significant decrease in interfacial thermal resistance and the formation of additional thermal conductive paths by the graphene coating layer, resulting in the significant improvement in thermal conductivity of EP/Al₂O₃@HGO composites. The flame retardant parameters, peak heat release rate, total heat release and total smoke production, showed a 49.3%, 40.9% and 71.2% reduction, respectively, comparing to neat EP, which was ascribed to the strong interface with GO coating layer and the flame retardant bridging agent catalyzed charring to form an intact and compact char protective layer with Al₂O₃. Moreover, the strong interfacial interaction also restricted the segment movement, increasing the storage modulus and T_g.