A Temperature-Ultraviolet-Responsive Fluorescent Anti-Counterfeiting Hydrogel

Information security and anti-counterfeiting are crucial across various industries. To address the limitations of traditional anti-counterfeiting materials, including low responsiveness, easy replication, and poor environmental stability, a fluorescein (Flu) loaded zeolitic imidazolate framework (ZIF-8) photothermal-responsive anti-counterfeiting hydrogel was designed. Flu was first confined within ZIF-8 via a one-pot method and then embedded into a polyacrylamide/lauryl methacrylate (PAM/LMA) network. This hydrogel emits intense green luminescence under 365 nm UV illumination. Its fluorescence can be quenched by Fe³⁺ and recovered upon exposure to PO₄^3-, which endows the material with rewritable data storage capacity. Sodium dodecyl sulfate (SDS) and sodium chloride (NaCl) in the hydrogel provide a temperature-dependent reversible transparency transition, allowing multi-level information encryption through the synergistic action of temperature, ions, and UV light. In addition, the hydrogel also features low toxicity, degradability, and an environmentally friendly solvent-free synthesis. This work demonstrates a multi-stimuli responsive strategy that overcomes the limitation of traditional single-responsive anti-counterfeiting materials, offering a promising approach for the design of rewritable and eco-friendly intelligent anti-counterfeiting systems and serving as a reference for the development of multifunctional responsive materials.