High Thermal Conductivity Liquid Metal/AlN Thermal Interface Materials Enabled via a Self-Assembled Monolayer Strategy

Thermal interface materials are critical to restrict the development of energy equipment for pursuing much higher power efficiency due to the existence of interfacial thermal resistance. This study developed a liquid metal/AlN composite based on self-assembled monolayer interfacial engineering. Through plasma hydroxylation and silane coupling agent modification, a complete chemical bonding bridge was constructed between the AlN fillers and the liquid metal matrix for achieving molecular-level interfacial bonding between them. One end of the silane molecule forms a covalent Al–O–Si bond with the AlN surface, while the other end establishes a stable chemical bond with the liquid metal via its terminal functional group. Systematic investigation revealed that the composite with 40 nm AlN fillers, a 10 wt % filling ratio, and modified with (3-chloropropyl)triethoxysilane exhibited the optimal thermal performance, achieving a thermal conductivity of 57.4 W·m–1·K–1 and an effective thermal resistance as low as 0.122 K·cm2·W–1, which is 22.78% lower than the unmodified sample. Practical application results demonstrated that the prepared material enables an output voltage of 2.7 V in a thermoelectric generator system, representing a 1.45-fold increase compared to the condition without TIM. In chip cooling applications, it reduces the chip’s excess temperature by 24.02 °C, achieving a 50.8% reduction. This research provides an effective interfacial engineering solution for realizing high-performance liquid metal-based thermal interface materials.