Dual-Key Dynamic Encryption: Moisture and Ion-Responsive Aggregation-Induced Emission Hydrogel for Multidimensional Anti-Counterfeiting

Fluorescent hydrogels hold significant promise for information encryption, yet often suffer from signal instability under environmental fluctuations or limited responsive modes. Here, a fluorescent hydrogel with antiswelling properties was fabricated via micellar copolymerization of acrylic acid (AAc) and lauryl methacrylate (LMA), incorporating the pH-responsive aggregation-induced emission (AIE) agent tetra-(4-pyridylphenyl) ethylene (TPE-4Py). The reversible protonation/deprotonation of TPE-4Py, coupled with dynamic structural changes in the polymer network during hydration/dehydration cycles, enabled the fluorescent hydrogel to exhibit a reversible fluorescence wavelength shift from 545 to 508 nm, accompanied by significant intensity variations. Furthermore, the fluorescent hydrogel displayed distinct fluorescence responses to different metal cations. By leveraging specific metal cations, their concentrations, and environmental humidity, the hydrogel allowed flexible information encryption, enhancing data security. This multidimensional strategy effectively overcame the limitations of conventional static or single-mode encryption. This platform provided a reliable and interference-resistant solution for advanced dynamic anticounterfeiting technologies and secure information storage.