Electrospinning Machine | Tailored Electro-Magnetic-Porous Multigradient Nanoarchitectonics for Absorption-Dominated Electromagnetic Interference Shielding and Adaptive Multifunctionality

The development of 5G and IoT technology has led to the dense deployment of electronic devices, generating electromagnetic interference (EMI) that not only affects the stability of precision electronic systems but also threatens human health. Traditional metal shielding materials have defects such as high density, susceptibility to corrosion, and poor processability, and their strong reflection can cause secondary radiation. Recently, Professor Wang Guilong from Shandong University developed a lightweight, flexible EMI shielding material with high shielding effectiveness, low reflectivity, and multifunctionality, resolving the inherent contradictions of traditional materials through a "composition-structure multigradient" design. The related research findings were published in the journal Advanced Science under the title “Tailored Electro-Magnetic-Porous Multigradient Nanoarchitectonics for Absorption-Dominated Electromagnetic Interference Shielding and Adaptive Multifunctionality”.

This study prepared a multifunctional electromagnetic interference (EMI) shielding film with a conductivity-permeability-pore size gradient structure through shear-induced in-situ fibrillation combined with layer-by-layer assembly technology. Under strong shear force, carbon nanotube (CNT) nanofibers and polytetrafluoroethylene (PTFE) nanofibers intertwine to form an interpenetrating dual-nanofiber network, which not only firmly anchors Fe₃O₄ nanoparticles but also constructs continuous conductive and thermal pathways. Furthermore, this unique dual-nanofiber structure, combined with the inherent properties of its components, endows the PTFE/CNT/Fe₃O₄ gradient (FCFe-G) film with excellent mechanical properties, superhydrophobicity, flame retardancy, and corrosion resistance.
More importantly, leveraging the multi-gradient-induced synergistic mechanism of "impedance matching - multi-level polarization - re-absorption", this FCFe-G film (thickness 101.1 μm) achieved absorption-dominated electromagnetic interference shielding, with an electromagnetic interference shielding effectiveness (SE) as high as 53.79 dB and an extremely low reflectivity (0.38). Additionally, anisotropic thermal management and CNT-driven negative temperature coefficient behavior contribute to rapid heat dissipation and early fire warning. The film's dual-mode electro-/photothermal response also enables its application in areas such as aerospace de-icing, medical thermotherapy, and antibacterial uses. This work introduces a "composition-structure multigradient" design paradigm, providing a promising strategy for intelligent electromagnetic interference shielding in aerospace, flexible electronics, and smart wearables.

Figure 1. Preparation process of the FCFe-G multigradient nanofiber membrane.

Figure 2. Microstructural morphology and structural characterization of FCFe film and FCFe-G film.

Figure 3. Characterization and macroscopic properties of the FCFe-G film.

Figure 4. Electromagnetic interference shielding performance of FCFe film and FCFe-G film.

Figure 5. Theoretical and simulated electromagnetic interference shielding performance of FCFe film and FCFe-G film.

Figure 6. Anisotropic thermal conductivity and fire sensing capability.

Figure 7. Electro-/photothermal conversion performance of the FCFe-G film.

Conclusion
In summary, a lightweight and flexible FCFe-G multifunctional composite film with a multi-gradient structure was successfully prepared through a shear-induced in situ fibrillation strategy combined with layer-by-layer assembly. This film demonstrates excellent electromagnetic interference (EMI) shielding performance. The synergistic effect of the interconnected dual-nanofiber network within the layers and the interlayer nanofiber pinning mechanism endows the FCFe-G film with a remarkable tensile strength of 27.14 MPa, along with integrated superhydrophobicity, thermal stability, and chemical corrosion resistance. 

By simultaneously optimizing the hierarchical porous framework and the distribution of electromagnetic fillers, this triple-gradient structure (electrical–magnetic–porous) minimizes impedance mismatch. As a result, the FCFe-G film, with a thickness of only 101.1 μm, achieves an EMI shielding effectiveness (SE) of 53.79 dB and a reflection coefficient as low as 0.38, relying on an "absorption–reflection–reabsorption" shielding mechanism. Notably, its normalized specific shielding effectiveness (SSE) reaches 9539.52 dB·cm²·g⁻¹, surpassing many traditional reflection-dominated shielding materials.

Furthermore, due to its anisotropic structural design, the FCFe-G film exhibits significant directional differences in thermal conductivity: the in-plane thermal conductivity is 11.46 W·m⁻¹·K⁻¹, while the through-plane thermal conductivity is only 0.45 W·m⁻¹·K⁻¹, resulting in an anisotropy ratio of 25.47. Additionally, the film integrates excellent flame retardancy and temperature-responsive characteristics, showing great promise for early fire warning applications. By constructing a continuous carbon nanotube conductive network, the FCFe-G film reaches a steady-state heating temperature of 156.9 °C under a low driving voltage of 4 V and 159.7 °C under an optical power density of 400 mW·cm⁻², demonstrating potential for medical thermotherapy, de-icing, and antibacterial applications.

This study overcomes the long-standing technical limitation of "high reflection–low absorption" in traditional shielding films through multi-gradient structural engineering, laying a theoretical foundation for next-generation "structure–function integrated" EMI shielding materials. With its multidimensional integration of mechanical robustness, environmental adaptability, and intelligent thermal responsiveness, the FCFe-G film holds significant potential for applications in spacecraft electromagnetic compatibility, flexible electronic packaging, and smart wearable devices, promoting the advancement of EMI shielding materials toward sustainability, intelligence, and multifunctionality.

Original link: https://doi.org/10.1002/advs.202511234