Flexible intelligent electromagnetic shielding polymer composites with sensitive on/off switching and high absorption

Abstract

The development of absorption-oriented intelligent switchable electromagnetic shielding materials has presented a promising solution for combining data transmission and electromagnetic shielding, and effectively reducing the secondary pollution caused by electromagnetic waves. However, it remains a challenge to achieve high electromagnetic interference shielding effectiveness (EMI SE) and a great absorption coefficient while adapting to certain deformations. Herein, a nickel-plated silicon carbide whisker (Ni@SiCw) is introduced to enhance the absorption properties through electroless plating under dielectric loss and magnetic loss. Ni@SiCw/polyurethane (TPU) is prepared by solution blending and hot pressing. Additionally, silver nanowires (AgNWs)/TPU layers are fabricated by electrospinning and vacuum-assisted filtration. The Ni@SiCw/TPU layer is then bonded with the AgNWs/TPU layer using waterborne polyurethane, fabricating a composite material with an electromagnetic isolation structure. This structure adopts the absorption–reflection–reabsorption shielding mechanism, which allows the composite material to achieve both great EMI SE (49.87 dB) and A (0.72). Furthermore, the material demonstrates the ability to switch the electromagnetic shielding efficiency (15.97–45.92 dB) within a range of 30% strain deformation. Moreover, after 200 tensile cycles, there is no significant decline in its electromagnetic shielding performance, which provides a reference strategy for the development of intelligent electromagnetic shielding materials.