Synergistic enhancement of thermal conductivity in thermal interface materials by fabricating 3D-BN-ZnO scaffolds

Three-dimensional boron nitride/zinc oxide (3D-BN-ZnO) scaffolds were prepared by the ice-templating method, in which ZnO particles were in situ formed by sintering. Then, polydimethylsiloxane (PDMS)/3D-BN-ZnO composites were fabricated via vacuum infiltration of PDMS prepolymer into the scaffolds and curing. Compared with the composite prepared by simple blending, the thermal conductivity of the composite prepared based on the ice-templating method is much higher due to the excellent orientation of hexagonal boron nitride (hBN) sheets. Based on the same content of hBN sheets, the further introduction of 2.7 wt% ZnO particles formed in situ by sintering could promote the thermal conductivity of the composite to the value of 1.45 W m −1 K −1 , which is 70.6% higher than that of the PDMS/3D-BN composite. In addition, compared with the PDMS/3D-BN composite containing more hBN sheets, the PDMS/3D-BN-ZnO composite with 2.7 wt% ZnO particles possesses fewer fillers but higher thermal conductivity. It suggests that ZnO particles could synergistically improve the thermal conductivity. As revealed from the morphology of the composites, many ZnO particles are located between hBN sheets and thus construct thermally conductive paths. This study provides a new strategy for the design of thermal interface materials with high thermal conductivity.