Magnetically Reconfigurable Liquid Metal Microdroplet Networks Enable High Thermal Conductivity and Self-healing in Dynamic Polymer Composites

The integration of high thermal conductivity and autonomous self-healing capability in thermal interface materials remains a critical challenge for next-generation electronic devices. Herein, we design a liquid metal (LM) magnetic droplet composite: TA-coated iron particles (Fe@TA) are compounded with Ga68.5In21.5Sn10, ultrasonicated into LM magnetic droplets, and dispersed in a dynamic polymer matrix. The TA shell architecture serves a dual function: it prevents deleterious alloying between iron and gallium-based LM, while the polyphenolic moieties of TA establish coordination interactions with Fe2+/Fe3+ and Ga3+/In3+ ions, synergistically ensuring interfacial structure and the stability. Under magnetic actuation, Fe@TA enables the directional migration and controlled deformation of LM droplets within the matrix, promoting droplet–droplet contact and the formation of efficient thermal pathways. Meanwhile, the magnetic field guides the droplets toward the damaged region, inducing matrix displacement to close the fracture gap and facilitating dynamic bond reformation, which substantially enhances the self-healing capability. Remarkably, the healed LMMC70 composite exhibits a 100% enhancement in thermal conductivity compared to its pristine sample, attributable to the synergistic magneto-thermal effect that drives droplet aggregation at damage sites, reinforces interfacial thermal contacts, and restores structural continuity through effective dynamic bond reorganization. In addition, the LMMC90 composite integrates high thermal conductivity (5.6 W·m–1·K–1), ultralow contact thermal resistance (0.1 K·cm2·W–1), excellent electrical insulation (1011 Ω·m), and effective self-healing capability. This work offers a viable strategy for designing intelligent thermal interface materials with magnetic-field-assisted thermal management and autonomous damage healing, holding great promise for reliable thermal management in advanced electronics.