Abstract: Accompanied with the great progress on highly integrated soft electric devices consistent with the Moore’s law, the demand of heat management with high efficiency is increasing, which makes the polymer-based heat dissipating materials attract intensive interest from both scientific and industrial communities. Therefore, to meet the demand, the construction of thermal conduction network in the polymer matrix is essential to improve the thermal conductivity of polymer composites. Herein, a three-dimensional Si3N4-BN ceramic (3D-SNBN) framework was effectively prepared within one step by in-situ combustion synthesis using low-cost Si, B2O3 and α-Si3N4 as raw materials and polymethylmethacrylate (PMMA) as pore forming agent. High-performance epoxy composites (SNBN/EP) were then prepared by impregnating epoxy resin (EP) into the 3D-SNBN framework. The thermal conductivity of the composites with a 3D-SNBN framework loading of 57.9 vol% was as high as 6.4 W·m-1·K-1, which exhibited a significant enhancement of 2809% and 644% compared with pure EP (0.22 W·m-1·K-1) and epoxy composites with conventional randomly dispersed Si3N4-BN powders (0.86 W·m-1·K-1). In addition, the composites exhibited outstanding thermal behaviors during heating and cooling processes accordingly, which further demonstrates its reliability and wide applying potential in industrial heat management. The discovery not only provides a feasible material candidate for heat transfer in the future, but also offers a general strategy in high thermal conductive polymer matrix design and preparation.

Key words: High thermal conductivity, Polymer composites, Porous Si₃N₄-BN ceramic, In-situ combustion synthesis, Heat management