Flexible CoFe2O4@CNT/ANF-PMXene-CNT/ANF multilayer films with magnetic-electric bi-continuous gradient structure for EMI shielding and thermal camouflage

The rapid escalation of electromagnetic (EM) wave pollution and secondary radiation underscored the urgent need for electromagnetic interference (EMI) shielding materials with reduced reflectivity. Previous research predominantly emphasized the incorporation of magnetic fillers, often neglecting their synergistic integration with spatial architecture, thereby constraining the multifunctionality of EMI shielding systems. In contrast, layer-by-layer (LBL) fabrication technology offered precise control over microstructures and enabled multifunctional integration, which had been effectively applied in areas such as supercapacitors, controlled drug release, nanofiltration membranes and EMI shielding. By constructing tailored layered configurations, this approach facilitated tunable attenuation of electromagnetic waves. Herein, aramid nanofibers (ANF), carbon nanotubes (CNT), MXene and cobalt ferrite (CoFe 2 O 4 ) were employed to fabricate a multilayer film featuring a magnetic-electric bi-continuous gradient structure via LBL assembly. Owing to its hierarchical architecture, the (Z 1 -Z 2 -Z 3 )CoFe 2 O 4 @CNT/ANF-PMXene-CNT/ANF ((Z 1 -Z 2 -Z 3 )CoC/A-PM-C/A) films demonstrated exceptional EMI shielding performance. Particularly, the (80-40-10)CoC/A-PM-C/A composite film achieved a high EMI shielding effectiveness (EMI SE) of 63.6 dB and exhibited a low reflection coefficient (R) of 0.613, while maintaining favorable mechanical properties, including a tensile strength of 51.2 MPa and toughness of 5.67 MJ m −3 . Simultaneously, the films exhibited superior thermal camouflage capability with a mid-infrared (IR) emissivity as low as 2.61% in the 7∼17 μm range, and displayed effective Joule-heating characteristics. This work introduced a novel strategy for the development of advanced EMI shielding materials, and the resulting (Z 1 -Z 2 -Z 3 )CoC/A-PM-C/A films demonstrated considerable promise in applications involving EMI suppression, infrared stealth, and electrothermal conversion.