Ultrathin polyimide-based composites with efficient low-reflectivity electromagnetic shielding and infrared stealth performance

Researching and manufacturing materials that possess both electromagnetic interference (EMI) shielding and infrared stealth capabilities is of great significance. Herein, an ultrathin polyimide-based nonwoven fabric with low-reflection EMI shielding/infrared stealth performance is successfully fabricated by in-situ loading of Fe₃O₄/Ag nanoparticles on the surface of polyimide (PI) fiber (PFA), and followed by bonding with a commercial Cu/Ni mesh. The synergistic assembly of PFA and Cu/Ni promotes the rational construction of hierarchical impedance matching, inducing electromagnetic waves (EMW) to enter the composite and be dissipated as much as possible. Meanwhile, the existence of Cu/Ni mesh on back of PFA facilitates the formation of electromagnetic resonance and destructive interference of EMW reflected from composite, leading to a lower-reflectivity (0.26) EMI shielding performance of 58 dB within 24–40 GHz at a thinner thickness (430 µm). More importantly, the fluffy PFA nonwoven fabric and metal Cu/Ni mesh endow composite with good thermal insulation and low infrared emissivity, resulting in excellent infrared stealth performance in various environments. As a result, such excellent compatibility makes it possible to become a promising defense material to be applied in military tent for preventing electromagnetic and infrared radiation.