Structural Engineering of Coaxial Fibers Toward Magnetic‐Dielectric‐Conductive Synergy for High‐Performance EMI Shielding

ABSTRACT The rapid evolution of the electronic information industry has brought both benefits and a significant challenge: electromagnetic interference. Such interference can cause severe disruptions to human health and the operation of precision instruments. However, conventional EMI shielding materials often have excessive weight, limited surface area, and low efficiency, which hinder their practical use. To overcome these issues, this paper proposes a composite strategy combining coaxial electrospinning and interfacial functionalization, yielding lightweight, flexible shielding materials with multi‐level electromagnetic loss mechanisms. By embedding FePc/Fe 3 O 4 @ZIF‐67 magnetic composite fillers with a strong coupling effect into the fiber shell layer, constructing a relatively conductive network with carboxylated MWCNT in the fiber core layer, and in situ depositing silver nanoparticles on the surface, a magnetic‐dielectric‐conductive multi‐interface synergistic structure is formed. The resulting composite film achieves an excellent shielding effectiveness of 62.349 dB at a thickness of only 0.197 mm, with a specific shielding efficiency of 12 356.136 dB·g −1 ·cm 2 . Furthermore, thanks to the excellent hydrophobicity and thermal stability of BPAPEN, the membrane exhibits excellent anti‐fouling performance and long‐term stability, significantly broadening its potential in diverse application scenarios. This work offers new insights into the rational design of flexible EMI shielding materials featuring multi‐interface synergy and structural tunability.