A Leakage-Free Solid–Solid\nPhase Change Composite\nwith High Thermal Conductivity and EMI Enabled by Covalent Functionalization\nand a Quasi-Hyperbolic Framework

With the rapid advancement of artificial intelligence,\nsmart sensing\ntechnologies, and batteries with high power density, thermal management\nhas become a critical issue for electronic devices. Phase change materials\n(PCMs) offer promising applications in thermal management. However,\nit is a significant challenge to fabricate PCMs with high thermal\nconductivity (TC) and electromagnetic interference shielding effectiveness\n(EMI SE) while maintaining a leakage-free performance. This work reports\nleakage-free solid–solid phase change composites with high\nTC and EMI SE enabled by covalent functionalization and a quasi-hyperbolic\nframework. The solid–solid phase change material (OP) is synthesized\nvia a nucleophilic ring-opening reaction of epoxy groups, where octadecanol\n(OD) is grafted onto the side chains of polyethylene-<i>co</i>-methyl acrylate-<i>co</i>-glycidyl methacrylate (PEMAGMA).\nSubsequently, it is filled into the electrochemically expanded graphite\n(EEG) framework through vacuum filtration, in which the EEG framework\nis produced using an electrochemical expansion method and has high\nTC and EMI SE. The obtained OP/EEG composites exhibited excellent\nproperties, including very low leakage (0.6%), high latent heat (86.45\nJ/g), ultrahigh TC (22.6 W/(m·K)), and superior EMI SE (110.28\ndB). This material shows great potential for improving the heat transfer\nefficiency of thermal interface materials (TIMs) in practical applications,\ndemonstrating a promising outlook in the field of thermal management.