Multi-stimuli responsive lanthanides-based luminescent hydrogels for advanced information encryption

The development of information storage materials and techniques with enhanced security level is still great challenging. Herein, the luminescent hydrogels were facilely prepared by doping luminescent lanthanide complexes into non-covalent cross-linked gelatin/poly(vinyl alcohol) hydrogels. The acquired luminescent hydrogels exhibited reversible luminescent switching behavior upon HCl/NH 3 and Fe 3+ /EDTA 2− stimuli, respectively. Remarkably, such reversible luminescent switching property of the hydrogels allows themselves as good candidates for rewritable information security storage. The written patterns were invisible under daylight, however can be clearly observed under UV light, suggesting their potential applications in information protection. Moreover, luminescent hydrogels with low toxicity possessed appealing shape memory and self-healing properties simultaneously. The combination of shape memory and self-healing properties with reversible luminescent switching property can access advanced information encryption effectively. Such encrypted information can only be decrypted by specific predesigned procedures with multi-steps. This work provides an alternative strategy to design and fabricate smart optical soft materials for advanced information encryption.