Multiscale study on the synergistic effect of interface heat transfer and filler structure on enhancing the thermal conductivity of boron nitride/alumina/ polyurethane composites

The design and preparation of polymer composites for microelectronic package with high thermal conductivity is an important route to solve the thermal problem of electronic devices. The synergistic effect of interface heat transfer and hybrid filler structure on the enhancement of thermal conductivity in polyurethane composites was analyzed using a multiscale approach. Firstly, the interface heat transfer characteristics and strengthening mechanism of BN-TPU and Al2O3-TPU regulated by functionalization were analyzed by atomic scale calculation. Then, the thermal conductivity of BN/Al2O3/TPU composites under different interface thermal resistance, filler distribution, filler ratio and contents were studied through representative volume elements with interface layer structure. The results indicate that, due to the functionalized molecules increasing the phonon vibration overlap between the filler and matrix and thereby reducing the interface thermal resistance, the thermal conductivity of the composite materials shows an increasing trend with interface functionalization. Moreover, under the combined effects of constructing oriented BN structures, optimizing the ratio between BN and Al2O3, and regulating interface functionalization, the composites showed excellent thermal conductivity at low filler content. The research can provide important guidance for the preparation of highly thermal conductive polymer composites.