Magnetized carbon microsphere and chitosan-functionalized BN hybrid network in stearic acid–epoxy composites for synergistic thermal management and EMI shielding

Developing multifunctional materials that simultaneously address thermal and electromagnetic interference (EMI) challenges is essential for next-generation miniaturized electronic systems. In this study, a chemically bonded stearic acid–epoxy phase-change polymer (SAEP) composite was engineered using magnetized carbon microspheres (MCMs) and chitosan-functionalized boron nitride (CBN) to achieve integrated thermal management, EMI shielding, and mechanical reinforcement. The MCMs, comprising a carbon framework embedded with iron oxide nanoparticles, facilitate both thermal conduction and magnetic-loss-driven EMI absorption. CBN provides high intrinsic thermal conductivity while improving interfacial compatibility with the SAEP matrix because of chitosan-assisted functionalization. Owing to the synergistic effects of these fillers, the optimized SAEP/MCM/CBN composite achieved a through-plane thermal conductivity of 5.11 W·m −1 ·K −1 , demonstrating a twenty-two-fold improvement over pristine SAEP, while maintaining a high latent heat of 90.5 J·g −1 to ensure effective heat storage and phase-transition stability. The composite also exhibited strong EMI shielding performance, reaching 65.2 dB within the X-band (8.2–12.4 GHz), with absorption as the dominant mechanism, thereby minimizing secondary electromagnetic reflection. Infrared thermal imaging further confirmed rapid heat dissipation, with CPU surface temperatures reduced by more than 25 °C during operation. Mechanical testing revealed significant enhancements in both tensile strength and elongation due to the interconnected hybrid filler framework. Collectively, these results highlight that combining MCMs with functionalized ceramic fillers within a chemically integrated phase-change material matrix enables simultaneous heat dissipation, EMI attenuation, and mechanical durability. The SAEP/MCM/CBN composite, therefore, represents a robust and scalable platform for advancing thermal interface and EMI shielding in high-power electronic systems. • PCM composite integrates thermal, EMI, and mechanical functionalities • MCM enables magnetic loss and thermal conduction via a carbon–Fe 3 O 4 network • CBN enhances thermal conductivity with interfacial compatibility • EMI SE reaches 65.2 dB via absorption-dominant mechanism • SAEP/MCM/CBN composite achieves a through-plane thermal conductivity of 5.11 W/m·K