Abstract: With the rapidly evolving direction of wireless communication technologies and mobile electronic products towards high integration and miniaturization, the worldwide electromagnetic (EM) emission has been increasingly harmful. The advancement of novel electromagnetic interference (EMI) shielding materials is crucial for solving EM pollution, especially high-performance EMI shielding materials possessing high absorption efficiency, compressibility and superior flexibility characteristics. In this work, a porous silicone rubber composite with special layer-by-layer distribution structure was fabricated through repeated casting and supercritical carbon dioxide foaming. The introduced highly conductive silver-plated tetra-needle zinc oxide (Ag@T-ZnO) was deposited at the bottom due to its high density, which provided superior EMI shielding performance by reinforcing the conductive network through its advanced microstructure. By embedding a progressive concentration of Fe₃O₄@CNT and Ti₃C₂T_x, the absorbability of the composites is significantly improved and resulting in an “absorption-reflection-reabsorption” mechanism. Supported by electromagnetic simulations, the prepared composite foams exhibit an average EMI shielding effectiveness (SE) and absorption efficiency of 71.41 dB and 89.54 % within 8.2-12.4 GHz, respectively, along with remarkable compressible recovery and stability characteristics. Notably, the absorption efficiency of this composite foam reaches a maximum value (99.97 %) at 9.2 GHz because of the resonance attenuation for incident and reflected EM waves. This work presents a feasible strategy for the exploitation of light-weight, compressible and highly efficient EMI shielding materials, which is expected to be suitable for the next generation of wearable and handheld smart electronic products.

Key words: Electromagnetic interference (EMI) shielding, Microcellular structure, Progressive network, Silicone rubber