Fe3O4 and Ag micro/nano coating for high-efficiency flame retardancy and electromagnetic interference shielding

In order to solve the growing problem of electromagnetic radiation and accidental fires due to heat accumulation or electric heating smart clothing, electromagnetic shielding materials with fire resistance are urgently needed. Herein, a polydopamine-assisted polysulfonamide (PSA) nonwoven fabric was designed as a hydrophilic substrate and nano-silver was employed as a conductive layer. A mixed solution of Fe3O4 with ammonium polyphosphate (APP) was further treated to obtain the surface of microspheres with incombustibility. Interestingly, the micro-nano electromagnetic wave loss gradient enabled the PSA/Ag/Fe3O4/APP-1(PSA/AFA-1) fabric to exhibit efficient absorption-dominant electromagnetic shielding performance, and the optimized fabric exhibited an EMI SE value of 45.5 dB at X-band (8.2-12.4 GHz) with a shielding efficiency of 99.99 %, which remained stable under multiple twisting and bending. This study opens up a new idea for the preparation of fireproof EMI shielding materials with broad application prospects as well as next-generation multi-purpose garments.