High-Performance Thermal Interface Silicone Elastomer Based on Liquid Metal-Encapsulated Aluminum Nitride Filler and Mechanical Training Strategy

Aluminum nitride (AlN) is highly regarded for its high thermal conductivity and electrical insulation, making it a promising filler for thermal interface materials (TIMs). However, its practical application is limited by the hydrolysis of its crystal structure in humid environments, which causes performance degradation. Existing surface modification methods also struggle to simultaneously achieve high processing efficiency and enhanced material performance. To address these issues, we developed a novel surface modification strategy involving the grafting of sulfhydryl groups onto AlN particles, followed by encapsulation with a liquid metal (LM) layer. The resulting LM@AlN fillers were then incorporated into a polydimethylsiloxane (PDMS) matrix and cured to form thermally conductive composites. The LM@AlN/PDMS composite exhibits a through-plane thermal conductivity of 1.83 W·m^–1·K^–1 and an in-plane thermal conductivity of 20.32 W·m^–1·K^–1, along with a tensile strength of 1.46 MPa and an elongation at break of 168.73%. It also demonstrates excellent stability in deionized water and under high-temperature, high-pressure conditions, with minimal changes in thermal conductivity (1.9% and 3.0%, respectively) and no leakage of liquid metal. This enhanced stability improves the practicality of liquid metal composites and broadens their potential for applications in wearable electronics and soft robotics.