Simple Two-Component CDs/PVA Hydrogels Possess Dynamic High-Definition and Two-Stage Information Encryption Capability

Ensuring the fidelity and security level of stored information is essential for information carrier materials to safeguard data and prevent counterfeiting. However, low resolution, limited encryption modes, and complex fabrication hinder existing information carriers from meeting evolving technological demands. Herein, a solvent exchange strategy from DMSO to water is employed to stably anchor hydrophobic fluorescent carbon dots (CDs) with multiple emission states onto a 3D framework of poly(vinyl alcohol) (PVA) chains, forming a simple two-component CDs/PVA hydrogel with tunable fluorescent colors and recyclability. The hydrogel can accommodate a high CDs loading of up to 15% and remains functional even after 5 solvent exchange cycles. Through a noncontact photobleaching oxidation process of CDs, high-definition images that are distinct from the blurred ones induced by traditional chemical ink stimuli can be recorded onto the hydrogel, decrypted under UV light, and dynamically erased after being read. Additionally, the chemical stimulus response of CDs and the easy processability of PVA provide the CDs/PVA hydrogel with more diverse encryption modes. The combination of light and chemical stimuli enables two-stage encryption, where light writing ensures high-fidelity information storage, while chemical ink introduces interference, further increasing the decryption difficulty and enhancing the security of stored information. Furthermore, the reversible physical cross-linking allows this hydrogel to be easily recycled and reprocessed after use. This versatile strategy endows the material with enhanced information security and provides insights into the development of advanced information carrier materials.