Bioinspired Functional\nComposites for Enhanced Thermally\nConductivity via Fractal-Growth CuNP Fillers

Thermal conduction for electronic devices has attracted\nextensive\nattention in light of the development of 5G communication. Thermally\nconductive materials with high thermal conductivity and extensive\nmechanical flexibility are extremely desirable in practical applications.\nHowever, the construction of efficient interconnected conductive pathways\nand continuous conductive networks is inadequate for either processing\nor actual usage in existing technologies. In this work, spherical\ncopper nanoparticles (S-CuNPs) and urchin-inspired fractal-growth\nCuNPs (U-CuNPs), thermally conductive metal fillers induced by ionic\nliquids, were fabricated successfully through the electrochemical\ndeposition method. Compared to S-CuNPs, the U-CuNPs shows larger specific\nsurface contact area, thus making it easier to build a continuous\nconductive pathway network in the corresponding U-CuNPs/liquid silicone\nrubber (LSR) thermally conductive composites. The optimal loading\nof CuNP fillers was determined by evaluating the rheological performance\nof the prepolymer and the mechanical properties and thermal conductivity\nperformances of the composites. When the filler loading is 150 phr,\nthe U-CuNPs/LSR produces optimal mechanical properties (e.g., tensile\nstrength and modulus), thermal conductivity (above 1000% improvement\ncompared to pure LSR), and heating/cooling efficiency. The enhanced\nthermal conductivity of U-CuNPs/LSR was also confirmed through the\nfinite element analysis (FEA) overall temperature distribution, indicating\nthat U-CuNPs with larger specific surface contact areas exhibit more\nadvantages in forming a continuous network in composites than S-CuNPs,\nmaking U-CuNPs/LSR a promising and competitive alternative to traditional\nflexible thermally interface materials.