Herein, a multifunctional electromagnetic interference (EMI) shielding membrane with a conductivity-permeability-pore size gradient structure is fabricated via shear-induced in situ fibrillation coupled with layer-by-layer assembly. Under intense shear, carbon nanotube (CNT) nanofibers intertwine with polytetrafluoroethylene (PTFE) nanofibrils to form an interpenetrating dual-nanofibrous network, which not only robustly anchors Fe3O4 nanoparticles but also establishing continuous conductive and thermal pathways. Moreover, the integration of this unique dual-nanofibrous structure with the intrinsic properties of its components endows the PTFE/CNT/Fe3O4-gradient (FCFe-G) membrane with superior mechanical properties, superhydrophobicity, flame retardancy, and corrosion resistance. More importantly, leveraging a multigradient-induced "impedance matching-multilevel polarization-reabsorption" synergistic mechanism, the FCFe-G membrane (101.1 µm) achieves absorption-dominated EMI shielding with an exceptional EMI shielding effectiveness (SE) of 53.79 dB and ultralow reflectivity (0.38). Furthermore, anisotropic thermal management and CNT-driven negative temperature coefficient behavior facilitate rapid heat dissipation and early fire warning. The film's dual-mode electro/photothermal response further enables aerospace deicing, medical hyperthermia, and antibacterial applications. This work introduces a "composition-structure multigradient" design paradigm, offering a promising strategy for intelligent EMI shielding in aerospace, flexible electronics, and smart wearables.
Shao et al. (Thu,) studied this question.