Preparation and Encryption Application of Photosensitive Intelligent Hydrogels Based on Graphene Oxide-Modified Carbon Quantum Dots

In the information era, information security issues are becoming increasingly prominent, making the development of anticounterfeiting materials and technologies of great significance. Fluorescent organic hydrogels have been widely used in the past; however, their limited functionality results in a low security index and simplistic encryption–decryption modes, thereby restricting their further application in anticounterfeiting. To address this, we designed a fluorescent self-healing hydrogel based on a polyacrylamide/poly(acrylic acid) matrix. By exploiting the self-healing ability of the hydrogel, fluorescent and nonfluorescent components can be reassembled into mixed encoded patterns, thereby enabling information encryption. Furthermore, owing to the abundant hydrogen bonds in poly(acrylic acid), the hydrogel exhibits robust mechanical strength and self-repair capability, achieving a healing efficiency of ∼72% after 24 h of reconnection. The carbon quantum dots doped with graphene oxide show an optimal excitation wavelength of 440 nm and an emission wavelength of 540 nm, with a 25% increase in the fluorescence lifetime. Functionalizing the hydrogel and integrating it with photosensitive materials further enhance the encryption level. This work proposes an application of photosensitive self-healing hydrogels in information encryption.