A multifunctional phase‐change composite with high thermal conductivity, high electromagnetic interference and leakage‐free capability enabled by a hyperbolic‐like skeleton encapsulation and polymer blend

Phase‐change materials (PCMs) are attractive in thermal management, while the leakage, low thermal conductivity (TC) and high electromagnetic interference (EMI) limit their wide application. In this work, a highly thermally conductive PCM with anti‐leakage and EMI was obtained by a dual encapsulation: a polymer blend and an electrochemically expanded graphite (EEG) skeleton, in which EEG also played a role in enhancing thermal conduction and EMI. The octadecanol was first mixed with polyethylene‐ co ‐methyl acrylate‐ co ‐glycidyl methacrylate, and then the mixture was filled into EEG with vacuum assistance. Due to the dual encapsulation with polymer chain restriction and EEG, the composites obtained have a low leakage (<1%), a high enthalpy of melting (84.00 J g −1 ) and a high TC (24.24 W (m K) −1 ). At the same time, the composite material has a high EMI effectiveness of 94.80 dB. This simple preparation shows great potential for large‐scale fabrication of high‐performance and shape‐stable PCMs.