Multi-scale interface induced 3D percolation network in polymeric heterostructures for EMI shielding application

Abstract

For addressing the limitations of traditional metal-based electromagnetic interference (EMI) shielding materials, such as insufficient flexibility and susceptibility to corrosion, this study developed a fluorosilicone rubber (FVMQ) matrix composite with superior polarization response by constructing multi-scale heterogeneous interface structures. Multi-walled carbon nanotubes (MWCNTs) and silver-coated copper powder (Ag@Cu) were employed as functional fillers to optimize the electromagnetic and mechanical properties of the material system through precise regulation of the filler-matrix interface interactions. The metal-insulator interface formed between the Ag@Cu filler and the rubber matrix induces a strong interfacial polarization effect, thereby significantly enhancing the dielectric loss capacity of the material. Simultaneously, the three-dimensional network structure of MWCNTs not only improves the continuity of the conductive pathways but also markedly increases the crosslinking density of the composite due to its robust interaction with the rubber molecular chains. This multi-scale interface engineering effectively suppresses the formation of internal defects within the material, blocks water diffusion pathways, and enables the material to exhibit excellent corrosion resistance (contact angle >112°) and long-term stability. Results demonstrate that the heterogeneous composite possesses remarkable advantages in EMI shielding performance, achieving a shielding efficiency exceeding 109 dB. Notably, the material also exhibits superior electrothermal response characteristics under electric drive. It can achieve rapid temperature elevation above 130 °C under a low-voltage drive of 3.5 V, while maintaining outstanding mechanical properties (elongation at break >400%, tensile strength >3 MPa). The integration of EMI shielding, electrothermal conversion, and mechanical flexibility into a single multifunctional system highlights its potential for applications in complex environments. This study provides a critical interface design strategy for the development of next-generation flexible EMI shielding materials.