Multi-Stimuli responsive shape memory and fluorescence-switching composite hydrogel for information encryption

Recently, composite hydrogels with fluorescent properties have emerged as advanced materials for intelligent confidential information protection. However, developing a high-throughput 3D anticounterfeiting platform capable of storing, protecting, and displaying classified information on demand remains a significant challenge. Herein, it developed a composite hydrogel with multi-stimuli responsive shape memory and fluorescence-switching properties, offering a promising platform for 3D information encryption. Specifically, the hydrogel exhibited stimulus-responsive shape memory and recovery capabilities arising from the reversible formation and disruption of three distinct types of chemical bonds: ionic bonds, dynamic imine bonds, and dynamic metal–ligand coordination bonds. Simultaneously, its fluorescence-switching capabilities were driven by the fluorescence variations of the embedded carbon dots (CDs) in response to diverse stimuli, including salt solutions, pH changes, metal ions such as Fe³⁺, respectively. Based on these properties, the hydrogel was further developed as an advanced platform for the secure protection and controlled decoding of encrypted information. Moreover, the innovative use of stimulus-responsive materials could pave the way for advanced smart systems that dynamically adapt to their environments.