Bifunctional Structural Regulation of Polymer Composites for High‐Efficiency Electromagnetic Wave Absorption and Heat Dissipation

ABSTRACT Heat accumulation in electronic devices, which is caused by electromagnetic interference, has emerged as a critical threat to electronic components. Integrating broadband electromagnetic wave absorption (EMA) with high thermal conductivity (TC) is therefore crucial for ensuring device stability. However, in polymer composites, the structural requirements for achieving high TC and effective EMA often conflict with each other. Consequently, overcoming this structural design contradiction between TC and EMA performance in composites has become an urgent challenge. This work proposes a novel strategy for constructing a 3D bifunctional network. By controlling the selective distribution of functional particles within a styrene‐butadiene‐styrene (SBS) copolymer, we successfully constructed a continuous TC network based on boron nitride (BN) alongside mutually segregated EMA units containing carbon fiber (CF) and carbonyl iron (CIP). The resultant composites exhibit a broad effective absorption bandwidth (EAB) of 9.4 GHz and a high thermal conductivity of 3.855 W m ^{− 1} K ^{− 1} , representing performance that surpasses most reported composites. Furthermore, electromagnetic simulations confirm that the electromagnetic wave‐transparent TC network effectively enhances the impedance matching of the composites. This study thus provides a viable solution for developing high‐performance EMA composites with excellent TC, holding promising prospects for commercial applications.