Preparation of Graphene-Liquid Metal/Epoxy Resin Composites with Plant Stem-like Hierarchical Structure
Due to its excellent chemical corrosion resistance, electrical insulation and low cost, epoxy resin can be widely used in the electronic packaging industry. However, the intrinsic low thermal conductivity of epoxy resins ( 0.2 W·m-1·K-1 ) limits its application in thermal management. It is an effective method to increase the thermal conductivity of epoxy matrix composites by adding high thermal conductivity filler to epoxy matrix and forming ordered structure. In this work, graphene-liquid metal/epoxy resin composite with plant stem-like hierarchical structure was prepared by 3D printing technology and directional freezing method. Thermal conductivity of the composite in the vertical direction (40％ mass fraction total filler) was 5.56 W·m-1·K-1, which was about 2.47 times higher than that of the graphene-liquid metal epoxy blended composite at the same mass fraction. This excellent thermal conductivity was attributed to the formation of anisotropic stem-like thermal conductivity paths along the enriched graphene layered phase and the improved compatibility between the liquid metal and the epoxy resin. At the same time, the unique plant stem-like hierarchical structure enabled the composite to maintain excellent mechanical property. Compared with the pure photosensitive resin skeleton, the compressive strength of the graphene-liquid metal/epoxy with plant stem-like hierarchical structure in the transverse direction and longitudinal direction was increased by 192％ and 240％, respectively. Consequently, the graphene-liquid metal/epoxy resin composite can be used as the best choice of thermal interface materials in the electronics industry.
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