Transparent and Ionic Conductive Hydrogel Integrating Photochromism and Electromagnetic Interference Shielding for Smart Window Applications

Abstract

Smart windows capable of simultaneously regulating light and providing electromagnetic interference (EMI) shielding represent an emerging frontier in functional building materials. Herein, a novel conductive hydrogel (PAM-MS-Mo-NaCl) is developed to integrate photochromic behavior, optically transparence and excellent EMI shielding effectiveness (SE) in a single. By incorporating ammonium molybdate and sodium chloride, the material achieves rapid, reversible photochromic switching under UV irradiation while attaining an EMI SE of 42.9 dB in the X-band when its thickness is only 1.8 mm. The ratio of SE and thickness for the hydrogels with a transmittance of 82% reaches 238.3 dB/cm, exceeding the reported transparent and ironic conductive hydrogels. Furthermore, the hydrogel demonstrates robust mechanical properties (fracture stress of 39.9 KPa, elongation at break of 97%) and stable shielding performance after repeated deformation. This work presents a multifunctional hydrogel that merges adaptive optical regulation with efficient electromagnetic protection, offering a promising material strategy for next-generation smart windows and advanced transparent shielding applications.