Self-Healing Liquid Metal Microdroplet Composites with Enhanced Thermal Conductivity for Phase Change Thermal Interface Applications.

Abstract

Gallium-based liquid metals (LMs) uniquely fuse metallic and fluidic properties, making them promising advanced composites that are gaining significant research attention. Inspired by the biological mechanisms of skin repair and blood coagulation, a novel liquid metal microdroplet composite phase change thermal interface material (LM composites) was developed. It incorporates a wide-melting-range LM dispersed phase (LM droplets) that can leak, aggregate, fuse, and partially crystallize into In or InSn4 crystals, as well as a self-healing polymer matrix with dynamic covalent and noncovalent networks. This unique structure results in a dual self-healing mechanism that synergistically combines flow-deformation solidification (from the metal) with matrix restoration (from the polymer), leading to a superior and more reliable self-healing performance. Subsequently, LM droplets and LM composites have been characterized to comprehensively investigate the properties of LM composites. And the composites exhibited a remarkable increase in thermal conductivity after damage healing, with a percentage increase of more than 37.8%. This enhancement is attributed to the aggregation and reorganization of LM droplets at the damaged interfaces, establishing new, efficient thermal conductivity pathways. Furthermore, the working performance of the LM composites can also prove this point, in which the LED wick temperature of healed samples is relatively lower compared to the correlation-type composites. Overall, these findings establish a new paradigm for designing self-healing composites. This paradigm moves beyond a specific material combination by intelligently utilizing the phase change behavior of functional fillers rather than relying solely on their liquid-state properties and offers broader implications for the field.