Salt Spray Resistant Silver-Plated Graphite Flake/Polyurethane Foam for Efficient Electromagnetic Interference Shielding.

Porous polymer-matrix electromagnetic interference (EMI) shielding composites can effectively lower density, and their multiple interfaces facilitate microwave attenuation by enhancing the internal scattering of electromagnetic waves. However, owing to the large specific surface area originating from the porous structure, such materials generally suffer from poor salt spray corrosion resistance, which limits their applications in coastal and marine service scenarios. Here, silver-coated polydopamine-modified graphite flake (Ag/pG) was first prepared as the conductive filler. Subsequently, the Ag/pG was further surface modified with γ-aminopropyltriethoxysilane (KH550). Finally, the modified Ag/pG was incorporated into the polyurethane (PU) foam matrix via a co-foaming process, fabricating porous EMI shielding composites with good salt spray corrosion resistance. The KH550 could form an organosilane protective layer on the silver surface, passivating the metal surface and suppressing the corrosion process. Meanwhile, the amino moieties in KH550 could chemically bond with PU macromolecular chains, effectively improving the interfacial compatibility. Such dual functions synergistically enhanced the salt spray corrosion resistance of the composites. After eight cycles of salt spray corrosion testing, the prepared composites maintained EMI shielding effectiveness above 90 dB with negligible attenuation. This study offers a facile design strategy toward high-performance EMI shielding materials applicable to complex and harsh service environments.