Aramid Nanofiber/Polypyrrole Composite Films for Broadband EMI Shielding, Wearable Electronics, Joule Heating, and Photothermal Conversion

Abstract

With the rapid development of miniaturization, high power, and high integration of electronic components, multifunctional electromagnetic interference (EMI)-shielding materials have attracted tremendous attention. Herein, the flexible multifunctional EMI-shielding aramid nanofiber/polypyrrole (ANF/PPy) composite films are prepared through a facile vacuum filtration method, which exhibits excellent broadband EMI shielding performance, wearable sensing, Joule heating, and photothermal conversion. The ANF/ PPy-4 composite film with a thickness of 46 μm displays an outstanding EMI shielding effectiveness (EMI SE) of 35 dB in the frequency range of 6−26.5 GHz due to the introduction of conductive PPy. The EMI SE of the ANF/PPy-4 composite film per unit thickness can achieve 826.0 dB mm −1 . A tensile strength of 132 MPa and fracture strain of 5.2% can be achieved, indicating the superior mechanical properties of the ANF/PPy-4 composite film. Furthermore, the ANF/PPy composite film can monitor human motions (such as finger, wrist, elbow, knee, ankle, forearm, and throat) due to piezoresistive response. In addition, the saturation temperature of the ANF/PPy-4 composite film is about 77 °C at a low voltage of 5.0 V. Moreover, the temperature of the ANF/PPy-4 composite film can reach 54 °C via photothermal conversion under one sun irradiation. Multifunctional ANF/PPy composite films show enormous potential application for broadband frequency EMI shielding, wearable sensing, and personal thermal management.

Ti3C2Tx MXene- and Sulfuric Acid-Treated Double-Network Hydrogel with Ultralow Conductive Filler Content for Stretchable Electromagnetic Interference Shielding

“…(e) Schematic illustration of the EMI shielding mechanism of the M 20 S 12 PPH. (f) Normalized EMI SE after stretching and releasing at different strains of M 20 S 12 PPH and other conductors in the literature. − (g) Comparison of EMI SE at 26.5 GHz and conductive filler content of M 20 S 12 PPH and other landmark conductors. ,− …”

“…As shown in Figure g, MSPPH has the largest maximum EMI SE of 99 dB and the lowest conductive filler content of 0.6% among various landmark conductors (Supplementary Table S1). ,− The excellent mechanical and EMI shielding performance achieved at such a low conductive filler content positions MSPPH as a low-cost and promising EMI shielding material for next-generation flexible electronics.…”

Ferrite-Decorated Ultrathin and Lightweight Carbon Nanotube Film for Electromagnetic Interference Shielding

“…Meanwhile, electronic devices are becoming more and more miniaturized for emerging technologies, causing more electromagnetic interference (EMI). EMI is considered pollution because of its negative effects on communication systems and other electronic devices . EMI seriously impacts sensitive electronic devices used in hospitals, military applications, and communication .…”

“…Therefore, protection from EMI, called EMI shielding, is essential to operating electronic devices properly. EMI shielding is a mechanism designed to mitigate the effects of electromagnetic radiation or interference, effectively diverting them from the protected area and minimizing potential disruptions or malfunctions. − EMI shielding involves absorption ( A ), reflection ( R ), and transmission ( T ) waves, which represent the shielding effectiveness according to the materials’ electrical conductivity and magnetic permeability. − Considering these properties, metals such as copper have been widely used as EMI-shielding materials in devices. , However, metals do not fulfill the requirements of next-generation devices because of their relatively high density, being prone to corrosion, and inflexibility. Various studies have examined different alternative materials for ultrathin and lightweight EMI shielding. − MXenes, two-dimensional (2D) layered materials derived from transition metals, show promising performance as ultrathin EMI-shielding materials, but they still have limitations in their fabrication processes and scalability.…”

“…Various studies have examined different alternative materials for ultrathin and lightweight EMI shielding. − MXenes, two-dimensional (2D) layered materials derived from transition metals, show promising performance as ultrathin EMI-shielding materials, but they still have limitations in their fabrication processes and scalability. Additionally, several studies combined high-performance polymeric-based fibers such as aramid with MXene (28.1 dB at 4.5 μm thickness), polypyrrole (46 dB at 46 μm thickness), or aerogel (75.4 dB at 5.2 mm thickness) to boost EMI-shielding performance. ,, Likewise, these materials suffer from industrial and environmental drawbacks due to the production methods or limitations, such as thickness and electrical conductivity.…”