An elastomeric composite with tunable thermal and mechanical properties via liquid metal-flake graphite multiphase fillers

Soft composites with improved and tunable thermal conductivity, stretchability and load-bearing capacity may find fascinating applications in soft robotics and wearable devices. Unfortunately, thermally conductive soft composites with solid fillers usually show serious degradation in stretchability, while those with liquid fillers usually possess a weak load-bearing capacity. To overcome these limitations, an elastomeric composite with solid–liquid multiphase fillers, named as pre-mixed LM&FG/SR composite, is proposed here by incorporating flake graphite (FG) with high thermal conductivity into liquid metal (LM) and then dispersing the mixture in a soft silicone elastomer (SR). In comparison with the LM/SR composite and the FG/SR composite, the pre-mixed LM&FG/SR composite gains the highest thermal conductivity under the strain-free state as it possesses both the excellent thermal conductivity of the FG filler and the high-volume fraction of the LM filler. In addition, by controlling the volume fraction of the multiphase fillers and the volume ratio of LM to FG, the pre-mixed LM&FG/SR composite can gain tunable thermal and mechanical properties under the strained state and thus be applicable to complex situations in which both excellent heat-conducting capability and certain load-bearing capacity are required.