Multifunctional Heterostructure Composite for Electromagnetic Interference Shielding with Excellent Absorption Characteristics

Multifunctional electromagnetic interference (EMI) shielding materials have become a growing need for modern communication equipment. Nevertheless, there still remains a challenge in achieving an EMI shielding performance with high absorption characteristics. Herein, inspired by gravity induced deposition, the design of a relative distribution of Fe3O4 and a low melting point alloy (LMPA) in poly(vinylidene fluoride) (PVDF) was achieved by compression molding. Finite element analysis (FEA) shows that Fe3O4 located in the upper half of the composite makes incident EMWs rarely reflect on the surface, and the heterostructure composite has a higher electromagnetic power loss. Meanwhile, the LMPA dispersed in the lower half of the composite has synergism with Fe3O4 and achieves excellent high absorption characteristics through multiple reflections and absorb–reflect–reabsorb processes. With a thickness of 2.0 mm, the heterostructure PVDF@Fe3O4/40LMPA exhibits an excellent EMI shielding effectiveness of 56.26 dB at 10 GHz with an absorption coefficient as high as 0.99999. Additionally, the excellent photothermal properties and high conductivity of the composite enable it to have static and dynamic infrared thermal camouflage. This work provides a strategy for fabricating EMI shielding composites with excellent absorption characteristics and photothermal properties for electromagnetic radiation protection and infrared thermal camouflage.