Multi-layered rubber-based nanocomposites for absorption-dominant EMI shielding and adaptive infrared camouflage

Designing cutting-edge flexible electronics that seamlessly integrate into the infrared (IR) spectrum while providing absorption-dominated EMI shielding remains a formidable challenge. This requires a delicate balance between impedance matching for high electromagnetic wave (EMW) absorption, optimal electrical conductivity for efficient EMI shielding, and precise IR reflection control for effective camouflage, a synergy barely achieved in a single nanocomposite. This study introduces a novel approach, pioneering a step-by-step engineered distribution of carbon nanotubes (CNTs) and pyrolyzed magnetic metal-organic frameworks (MMOFs) within a multi-layered styrene-butadiene rubber (SBR) system. By increasing the CNT content gradient while reducing the MMOF content gradient across the layers, this approach unlocks a unique balance among impedance matching, electrical conductivity, and IR emissivity. The optimized 1-mm-thick nanocomposite achieved a shielding effectiveness of 54 dB with an absorption coefficient of 0.70, demonstrating the successful development of an absorption-dominant EMI shield capable of blocking 99.9996 % of incoming EMWs. It's remarkable that Joule heating capability also allows it to rapidly reach a steady-state temperature of 125 °C within 84 s under a 10 V driving voltage. This electro-thermal energy conversion ability complements IR camouflage, as the optimized nanocomposite can dynamically modulate IR radiation in response to fluctuating environmental temperatures, ensuring adaptive IR camouflage under varying conditions. Mechanically, the developed nanocomposite offers exceptional flexibility and durability, with an elongation at break of 134 % and a maximum tensile stress of 11.5 MPa. This multifunctional multi-layered nanocomposite integrates high EMW absorption, efficient EMI shielding, and IR camouflage, making it ideal for next-generation flexible electronics. • The asymmetric nanocomposite shows 54 dB EMI shielding with 70 % absorption. • EMI shielding and absorption are retained after 500 mechanical deformation cycles. • Asymmetric nanocomposite shows adaptive IR camouflage via Joule heating. • Flexible EMI shield exhibits 134 % elongation and a tensile strength of 11.5 MPa.