Enhancing Effective Anisotropic Thermal Conductivity and Electromagnetic Interference Shielding by Natural Cellular Channels of Wood and Liquid Metal/Cellulose Nanofiber Interface Engineering

This work achieved surface functionalization of liquid metal (LM) through interface engineering, introducing alkoxyl and carboxyl groups on its surface to facilitate strong interactions with the hydroxyl groups on Cellulose Nanofiber (CNF) to construct a continuous heat transfer network. This allowed LM to anchor onto the CNF tube walls, thereby promoting the formation of a thermally conductive network. The thermally conductivity of the CNF filled with thiomalic acid (TA) modified LM reaches 7.421 W/m·K, with a thermal conductivity anisotropy ratio of 23, which is 46 times higher than that of pure CNF. The heat transfer experiments reveal the high heat transfer efficiency of the composites, and further validation through finite element simulations demonstrate that the construction of a LM thermal network provides an effective pathway for phonon transmission. Additionally, the prepared composites exhibits outstanding electromagnetic interference (EMI) shielding performance with a shielding effectiveness of 32.11 dB and a conductivity of 25.64 S/m, capable of blocking 99.937% of incident radiation. This work provides a novel concept and valuable insight for the preparation of thermal interface composites with high thermal conductivity.