Tunable absorption-dominated EMI shielding enabled by an asymmetric foam-film composite with modular bi-conductive networks

Conventional electromagnetic interference (EMI) shielding materials predominantly reflect waves, causing secondary pollution, while achieving absorption-dominated shielding without complex structures or magnetic components remains a significant challenge. Inspired by the scrub sponge architecture, this study develops a CNTs/MF-PA foam-film composites with modular bi-conductive networks for tunable absorption-dominated EMI shielding, where the porous foam serves as a regulatory component that modulates the electromagnetic response of the underlying organic coating. The asymmetric design, combining a carbon nanotube-loaded melamine foam (CNTs/MF) with a replaceable silver nanowire-based organic coating (PA), achieves 76.89 dB shielding effectiveness (SE) and 0.94 absorption coefficient (A) without magnetic components. Notably, by interchanging the bottom coating with varying EMI SE (20–80 dB), the overall shielding performance can be precisely tuned while maintaining an ultra-high A above 0.93, demonstrating universal foam regulation of different coatings for customizable shielding. The superior performance stems from synergistic effects where the foam layer ensures excellent impedance matching, promotes multiple scattering, and induces phase cancellation through extended propagation paths, while the organic coating provides robust shielding. This work offers a groundbreaking strategy for developing functional organic coating materials with tailored electromagnetic performance, holding immense promise for applications in flexible electronics and advanced aerospace systems.