Multifunctional Flexible Phase Change Composites With High Thermal Conductivity and Electromagnetic Interference Shielding

ABSTRACT Flexible phase change materials (PCMs) offer a promising strategy for addressing cross‐interface heat transfer and enabling efficient temperature regulation in electronic devices. However, their practical application is hindered by intrinsically low thermal conductivity. Herein, we develop a multifunctional flexible PCM by integrating intrinsically flexible solid‐solid PCM with multidimensional thermally conductive network. Through rational design of the solid‐solid PCMs structure and thermodynamic properties, construction of an efficient heat transfer network, and optimization of the component ratios, the thermodynamic properties, flexibility, and thermal management performance of the multifunctional PCM are systematically balanced. The resulting composite achieves high thermal conductivity of 5.1 W m − 1 K − 1 , satisfactory latent heat density of 63.9 J g − 1 , excellent cycling stability over 1000 heating/cooling cycles, and electromagnetic interference shielding effectiveness up to 74.31 dB, outperforming most previously reported multifunctional flexible PCMs. Moreover, when employed as a thermal interface material in a cooling system, the multifunctional PCM/FAN reduces the device temperature by 27°C, demonstrating a synergistic cooling effect through latent heat storage and enhanced thermal conduction. This work presents high‐performance, multifunctional flexible PCM with integrated thermal management and EMI shielding functionalities, providing a feasible strategy for optimizing the composition and performance balance of flexible PCMs.