Ice-templated assembly strategy to construct three-dimensional thermally conductive networks of BN nanosheets and silver nanowires in polymer composites

Polymer composites have been widely employed as electronic packaging materials, due to their low cost, flexibility, chemical stability, and high malleability, etc. However, the thermal conductivity of polymer composites becomes increasingly requirement, with the rapid growth of electronics toward miniaturization and high-power density. Conventional method to enhance the thermal conductivity of polymer is addition of high-content thermally conductive fillers, but it will deteriorate other significant properties of polymers, such as optical, electrical, and mechanical performance. Herein, we report an ice-templated assembly strategy to construct threedimensional thermally conductive networks of BN nanosheets (BNNS) and silver nanowires (AgNWs) in epoxy resin composites. The thermal-conduction pathway can be easily built by the synergistic effects between twodimensional BNNS and one-dimensional AgNW. Furthermore, the welding of the adjacent AgNWs through low-temperature sintering process enlarges the total contact area per unit filler volume. The resulted polymer composite thus exhibits a through-plane thermal conductivity of 1.10 Wm(-1)K(-1) at only about 5.0 vol% fillers content, which is six times higher than that of the pure epoxy resin. This work shows great potential in advanced packaging materials, such as substrate materials and printed circuit board materials.