Construction of denser networks via functionalized aluminum oxide‐boron nitride hybrid fillers: Towards improved thermal conductivity of polycarbonate composites

Abstract With the gradual acceleration of development in the modern electronics, there is a higher demand for insulating polymer composites with high thermal conductivity. Herein, the functionalized fillers were fabricated through first deposition of polydopamine (PDA) on boron nitride (BN) plates and then covalent modification of BN‐PDA and aluminum oxide (Al ₂ O ₃ ) by γ‐aminopropyltriethoxysilane (APTES), respectively. Hybridized filler‐filled polycarbonate (PC) composites were prepared by partially substituting Al ₂ O ₃ for BN plates with constant filler content. The PC composite filled with 9 wt% Al ₂ O ₃ and 21 wt% BN (PCA ₃ B ₇ ) achieved a thermal conductivity of 0.734 W mk ⁻¹ , which is 217% and 21% higher than that of pure PC (0.231 W mk ⁻¹ ) and PCB (0.605 W mk ⁻¹ ), respectively. Besides, the PC composites exhibit excellent electrical insulation properties (10 ¹³ Ω cm), relatively good mechanical properties, and enhanced thermal stability. This PC composite, characterized by its superior comprehensive performance, holds significant promise as a thermal management material in electrical and electronic device applications. Highlights Functionalized fillers were fabricated via covalent and non‐covalent methods. The appropriate proportion of hybridized fillers showed synergistic effects. The composite's thermal conductivity was 217% higher than pure PC. The composite exhibited desirable electrical insulating characteristics and thermal stability. The composite could act as a thermal management material.