Multilayer composite films with enhanced electromagnetic interference shielding and thermal management properties based on bamboo cellulose nanofibers

Flexible, lightweight, and versatile materials are key trends for the next generation of electromagnetic interference (EMI) shielding solutions. Conductive polymer composites have garnered significant attention in the field of EMI shielding. In this study, multilayer films consisting of bamboo cellulose nanofibers (BCNF)/silver nanoparticles (AgNPs) and conductive reduced graphene oxide (rGO)/multi-walled carbon nanotubes (MWCNTs) were prepared using a vacuum alternate filtration. Leveraging the inherent reducibility of BCNF, AgNPs were incorporated into the composite films to impart antibacterial properties. Stacking and concentrating rGO/MWCNTs into conductive layer resulted in multilayer films that exhibit excellent EMI shielding and thermal management properties. The composite films exhibited an EMI shielding effectiveness (EMI SE) of 37.59 dB in the X-band, achieving an SE/d (the ratio of SE to thickness) of 729 dB mm⁻¹, effectively attenuating 99.98 % of electromagnetic waves. Thanks to the outstanding electrical conductivity, the composite films exhibited excellent Joule heating performance, reaching a saturation temperature within 10 s. Furthermore, the composite films possess dual heating capabilities and can also be heated through photothermal conversion. This work presents a straightforward and environmentally friendly approach for fabricating multifunctional composite films that integrate both EMI shielding and thermal management, addressing the needs of environmental protection and sustainable development.