A multifunctional kapok cellulose nanofiber/MWCNT/Fe₃O₄ flexible multilayer film for electromagnetic interference...

With the rapid advancement of 5G communications and flexible electronics, electromagnetic interference (EMI) shielding materials with multifunctionality and environmental adaptability are urgently needed. Herein, we report a sustainable and cost-effective strategy to fabricate multifunctional multilayer films incorporating kapok cellulose nanofibers, MWCNT, and Fe₃O₄ nanoparticles. Specifically, films with 3-11 layers are obtained via sequential solution deposition and vacuum filtration. The multilayer architecture enhances interfacial polarization and multiple internal reflection, yielding an EMI shielding effectiveness of 46 dB for samples with 11 layers. Meanwhile, the synergistic combination of polymeric, conductive, and magnetic components endows the film with inherent flexibility, thermal stability, and additional functionalities, including photothermal conversion (reaching up to 108 °C under 2.0 sun illumination) and a Seebeck coefficient of 56.3 μV/K. This work provides an effective approach for integrating EMI shielding with energy-related functionalities in sustainable bio-based films, offering novel insights into the design of high-performance multifunctional EMI shielding materials.