Excellent electromagnetic interference (EMI) shielding ability, light weight, and good heat resistance are highly required for practical applications of EMI shielding materials, such as in areas of aerospace, aircraft, and automobiles. Herein, a lightweight and robust carbon nanotube (CNT)/polyimide (PI) foam was developed for efficient and heat-resistant EMI shielding. Thanks to poly(vinyl pyrrolidone) (PVP) as a surfactant that not only promotes the uniform dispersion of CNTs to form perfect CNT conductive networks but also can be removed in situ during the polymerization process, the density of resultant CNT/PI foam is only 32.1 mg·cm–3, and the EMI shielding effectiveness (EMI SE) is up to 41.1 dB, which represents one of the highest EMI SE values compared to previously reported polymer-based foams. The CNT/PI foam also achieves the absorption coefficient (A) of up to 82.3%, which is very impressive in CNT/polymer foams at comparable EMI SE levels. The PI matrix endows the foam with excellent heat resistance. The as-prepared CNT/PI foam presents a higher EMI SE than 35 dB even after being subjected to the flame of an alcohol burner. Moreover, the compressive strength and compressive modulus are up to 240.9 and 323.9 kPa. These results indicate its certain application potential in the harsh requirement of aeronautics and aerospace industries as a highly efficient and lightweight EMI shielding material.
Flexible strain sensors based on elastomeric conductive polymer composites (ECPCs) play an important role in wearable sensing electronics. However, the achievement of good conjunction between broad detection range and high sensitivity is still challenging. Herein, a highly stretchable and sensitive strain sensor was developed with the formation of porous segregated conductive network in the carbon nanotube/thermoplastic polyurethane composite via a facile and nontoxic compression-molding plus salt-leaching method. The strain sensor with porous segregated conductive network exhibited perfect combination of ultrawide sensing range (800% strain), large sensitivity (gauge factor of 356.4), short response time (180 ms) and recovery time (180 ms), as well as superior stability and durability. The integrated porous structure intensifies the deformation of segregated conductive network when tension strain is applied, which benefits enhancement of the sensitivity. Our sensor could monitor not only subtle oscillation and physiological signals but also energetic human motions efficiently, revealing promising potential applications in wearable motion monitoring systems. This work provides a unique and effective strategy for realizing ECPCs based strain sensors with excellent comprehensive sensing performances.
Superhydrophobic electromagnetic interference (EMI) shielding textile (EMIST) is of great significance to the safety and long-term service of all-weather outdoor equipment. However, it is still challenging to achieve long-term durability and stability under external mechanical deformations or other harsh service conditions. Herein, by designing and implementing silver nanowire (AgNW) networks and a superhydrophobic coating onto a commercial textile, we demonstrate a highly robust superhydrophobic EMIST. The resultant EMIST shows a synergy of high water contact angle (160.8°), low sliding angle (2.9°), and superior EMI shielding effectiveness (51.5 dB). Remarkably, the EMIST still maintains its superhydrophobic feature and high EMI shielding level (42.6 dB) even after 5000 stretchingreleasing cycles. Moreover, the EMIST exhibits strong resistance to ultrasonic treatment up to 60 min, peeling test up to 100 cycles, strong acidic/alkaline solutions, and different organic solvents, indicating its outstanding mechanical robustness and chemical durability. These attractive features of the EMIST are mainly a result of the joint action of AgNWs, carbon nanotubes, polytetrafluoroethylene nanoparticles, and fluoroacrylic polymer. This work offers a promising approach for the design of future durable, superhydrophobic EMISTs, which are capable of remaining fully functional against long-time exposure to extreme conditions, for example, wet and corrosive environments.
The utility of current electromagnetic interference (EMI) shielding textiles (EMISTs) for protecting the human body from high‐intensity electromagnetic radiation is limited by their high cost, low manufacturing efficiency, and poor stability under mechanical deformation. More importantly, no existing EMISTs are truly washable, which is critical for optimized protection with direct and conformal contact with human skin. In this paper, by integrating silver nanowire (AgNW) networks and a polyurethane (PU) protective layer onto a commercial textile, a machine‐washable EMIST with excellent EMI shielding effectiveness (EMI SE) (63.9 dB @ 3.0 wt% AgNW) is demonstrated. Here, the EMIST has several key advantages, which include the following: 1) remarkable washing durability (89% EMI SE retention after 20 machine‐washing cycles), 2) outstanding long‐term mechanical reliability, remaining stable under various deformation conditions (e.g., EMI SE retention of at least 82% after 5000 stretching cycles), and 3) excellent chemical stability. The research provides a high‐quality, affordable, and fully wearable EMIST that can protect engineers, soldiers, and civilians who work with, live near, or pass by electromagnetic or radioactive sources.
Conductive textiles (CTs) are promising electromagnetic interference (EMI) shielding materials. Nevertheless, limited stretchability and poor reliability restrict their potential applications in stretchable electronic devices because of the rigid conductive networks. Herein, a highly stretchable and reliable CT is developed for effective EMI shielding by designing a deformable liquid-metal (LM) coating and polydimethylsiloxane (PDMS) protective layer. The resultant PDMS-LM/Textile exhibits an outstanding EMI shielding efficiency (EMI SE) of 72.6 dB at a thickness of only 0.35 mm while maintaining EMI SEs of 66.0 and 52.4 dB under strains of 30 and 50%, respectively. The corresponding EMI SEs hold 91.7 and 80.3% retention after 5000 stretching−releasing cycles, respectively. The superior and durable EMI SE should be ascribed to the perfect connectivity and good deformability of conductive LM networks. Moreover, the LM coating has a robust fastness to the textile substrate, without any obvious decrease in EMI SE after 10 min of ultrasonic treatment and 100 peeling cycles because of the protective effect of the PDMS layer. This work provides a novel route to developing highly stretchable CTs for advanced EMI shielding applications, especially in the field of highly stretchable electronic devices.
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