Sustainable epoxy composites with high thermal conductivity using poly(lipoic acid) modified liquid metal as crosslinkers

With the increasing demand for electronics integration and the increasing accumulation of e-waste, thermal management materials combing high conductivity and sustainability is highly desired. Herein, bio-based recyclable epoxy composites with significantly improved thermal conductivity were prepared by utilizing poly(lipoic acid) modified liquid metal (LM) as the crosslinkers. The strong interactions between poly(lipoic acid) and LM enable the formation of a poly(lipoic acid) shell layer coating on the LM droplet core, which facilitates the dispersion of LM droplets as well as interfacial thermal transport in the composites. As a result, the composite with only 25 vol% LM exhibits a thermal conductivity of 0.82 W/(m·K), which is higher than those of the previous studies with randomly filled LM at the same loading. In addition, attributed to the existence of dual dynamic bonds (disulfide bonds and β-hydroxyl ester bonds), the composites are reprocessable and their thermal conductivities are maintained after reprocessing. Moreover, the composites can be degraded under mild reducing conditions. This work presents a novel approach for the preparation of high-performance thermal management materials featuring recyclability and degradability.