Castor oil-based polyurethane ternary composites with enhanced thermal conductivity and mechanical properties by using liquid metal as second filler

With the miniaturization, high frequency of electronic devices, and low-carbon and sustainable development, higher requirements are put forward for thermal conductive polyurethane composites in terms of comprehensive performance and renewable raw materials. Herein, choosing bio-based polyurethane (PU) derived from castor oil as matrix, and liquid metal (LM) and aluminum hydroxide (ATH) as hybrid thermal conductive filler, castor oil-based PU composites were developed via high-speed rotation and in-situ polymerization method. The LM-ATH hybrid filler displayed a synergistic enhancement effect on the thermal conductivity of composites due to the presence of LM-bridging significantly improved the effective contact probability between ATH fillers. The thermal conductivity of 50LM-ATH/PU reached 1.69 Wm-1 K-1, which was 9.9 times and 1.4 times higher than that of pure PU and 50ATH/PU, respectively. Notably, the 50LM-ATH/PU exhibited outstanding mechanical properties including tensile strength up to 4.0 MPa and adhesion strength up to 7.9 MPa, especially elongation at break up to 120% which was improved by 200% compared with 50ATH/PU (40%). Additionally, the composite possessed excellent electric insulation, thermal stability, and inflaming retarding properties, showing great application potential in the electronic devices field.Highlights Castor oil-based PU composites with ATH-LM hybrid filer were developed. LM-ATH hybrid filler of 2:8 promoted the thermal conductivity of composites. Hybrid filler than ATH-endowed composites with better mechanical properties. The ATH-LM/PU exhibited excellent electric insulation. Preparation flowchart and performance of LM-ATH/PU composites. image