Multifunctional melamine foam composites featuring asymmetric conductive networks for highly absorptive EMI shielding and infrared stealth

Abstract To address the growing need for lightweight and multifunctional stealth materials in modern protective applications, this study presents an innovative melamine foam (MF)-based composite featuring an asymmetric dual-nano conductive network with integrated absorption-dominated electromagnetic interference (EMI) shielding, infrared (IR) stealth, and flame retardant properties. Inspired by Salisbury screen, the composites employ MF as an interlayer and flame-retardant thermoplastic polyurethane (TPU) nanofiber membrane as a substrate. The architecture features a carbon nanotubes (CNTs)-modified impedance matching nanofiber layer as the top absorber and a silver nanoparticles (AgNPs)-modified nanofiber layer as the highly conductive reflective bottom. Precise control of CNTs content and interlayer thickness enables tunable electromagnetic waves (EMWs) absorption, yielding a low reflection (0.03) and high EMI shielding effectiveness (79.23 dB) at 4.40 mm. Even at 1.40 mm, effective absorption-dominated shielding is maintained. And the performance remains stable under ultrasonic, compression, and bending, demonstrating high durability. Especially, the mechanism behind achieving absorption-dominated EMI shielding at a reduced thickness, which relies on destructive interference of EMWs enabled by the asymmetric dual-nano conductive network, is thoroughly elucidated. Additionally, the composite exhibits superior IR stealth and self-extinguishing properties. This work offers a feasible strategy for designing high-performance stealth materials with strong potential for personnel and communication equipment protection.