Multifunctional Flame-Retardant Melamine-Based Hybrid Foam for Infrared Stealth, Thermal Insulation, and Electromagnetic Interference Shielding

Multifunctionalization is an important development direction of electromagnetic interference (EMI)-shielding materials. However, it is still a huge challenge to effectively integrate multiple functions into materials. Herein, we reported a facile method to fabricate multifunctional EMI-shielding materials, which were assembled with multidimensional components consisting of a 3D melamine–formaldehyde (MF) foam skeleton, 0D ferroferric oxide (Fe3O4) nanoparticles, and 1D silver nanowires (AgNWs) via coprecipitation and dip-coating processes. Due to the coaction of conductive AgNWs and magnetic Fe3O4 nanoparticles, the resultant hybrid foam showed excellent absorption-dominant EMI-shielding performances with a high specific EMI-shielding effectiveness value of 12,704 dB cm2 g–1. Moreover, thanks to the multilayer porous micro-/nanostructure and the nonflammability of functional coatings, the hybrid foam shows excellent flame retardancy and heat insulation, making it attractive for the functions of infrared stealth and heat insulation. The corresponding mechanism is discussed in detail. Combined with the advantages of high thermal insulation, flame retardancy, elasticity, and excellent absorption-dominant EMI-shielding performances, the hybrid foam showed great applications in the fields of both military and civilian. This work provides new inspiration and insights for the design of multifunctional high-performance EMI-absorbing materials.