Cationic Carbon Dot Reinforced Highly Tensile, Tough, Dehydration Resistant Polyelectrolyte Hydrogels with Fluorescence for Flexible Sensing and Information Anti‐Counterfeiting

Abstract With the rapid development of wearable devices, there is an increasing demand for multifunctional conductive soft materials. Nanocomposite hydrogels containing carbon nanofillers such as carbon dots (CDs) composite gels emerge as promising candidates. However, traditional CDs nanocomposite hydrogels face limitations in terms of mechanical strength, stability and elasticity. To overcome these critical challenges, in this work, a cationic carbon dots (CCDs)‐reinforced polyelectrolyte hydrogel engineered through synergistic electrostatic assembly and salting‐out strategies is developed. The polyacrylic acid/sodium hyaluronate/cationic carbon point glycerol‐water binary solvent fluorescent organohydrogel (PAH‐CG) is fabricated. The resulting organohydrogel PAH‐CG successfully overcame the plasticizing effect of glycerol, resulting in a significant enhancement of mechanical properties, with a 149‐fold increase in Young's modulus compared to the control hydrogel. Specifically, the PAH‐CG hydrogel exhibited high tensile strain (1200%–2734%), tensile strength (234 kPa), and modulus (275 kPa), alongside excellent elasticity, fluorescence, and dehydration resistance. The improvement in mechanical properties leads to excellent performance in flexible sensor applications. Concurrently, glycerol incorporation not only amplifies fluorescence intensity but also improves dehydration resistance and moisture absorption. Applications for encrypted transmission of information and anti‐counterfeiting have been developed based on these properties, making PAH‐CG hydrogels a promising platform for advanced smart devices.