Robust PI composites with high-connected AgNPs for multifunctional electromagnetic interference shielding in harsh environment

Durable and multifunctional electromagnetic interference (EMI) shielding materials have garnered significant attention due to their growing application demands. However, achieving optimal EMI shielding performance remains challenging, primarily due to the inherent interfacial resistance among conductive fillers. In this study, a novel polyimide@silver-sintered (PI@Ag–S) nanofiber composite was developed through in situ anchoring and low-temperature sintering of Ag nanoparticles (AgNPs) on electrospun PI nanofibers. The sintering process created a highly interconnected AgNPs layer, significantly reducing the electrical resistance and enhancing the electrical conductivity from 49 S/cm to an exceptional 154 S/cm. The resulting PI@Ag–S nanofiber composite demonstrated outstanding EMI shielding effectiveness (86.7 dB), and a remarkable SSE/t value of 14985 dB cm 2  g −1 , alongside excellent in-plane thermal conductivity (2.6011 W/(m⋅K)). Additionally, the composite showcased superior electrical heating performance, enabling effective defogging and de-icing operations at a low voltage of 1.5 V. Notably, the composite, protected by an ultrathin 8 μm PI coating, exhibited exceptional durability, including resistance to extreme temperatures, strong acid and alkali corrosion, and flame-retardant properties. These attributes make the flexible PI@Ag–S nanofiber composite a promising candidate for advanced EMI shielding and thermal management applications, particularly in harsh environments.