An organohydrogel with tunable fluorescence and shape-memory property for advanced anti-counterfeiting†

Counterfeiting is a significant threat in the intricate realm of global commerce, casting shadows over industries, economies, and unsuspecting consumers. Fluorescent anti-counterfeiting labels have been widely used in the past, but their level of security is still relatively inadequate. Therefore, the ongoing research is aimed at improving security through the encapsulation of information within predefined geometric structures. Herein, fluorescent organohydrogels with a hydrophilic polymer network of poly(N,N-dimethylacrylamide-acrylic acid) (P(DMA-AAc)), containing blue fluorescent monomers (PyMA), and a hydrophobic polymer network, polystearyl methylacrylate (PSMA), are fabricated by two-step interpenetrating polymerization. Upon treatment with Fe³⁺, the blue fluorescence of organohydrogels is quenched owing to the intramolecular charge transfer (ICT) effect, which can be reinstated by adding H⁺. Furthermore, coupled with the shape memory function induced by the crystallization of PSMA, the organohydrogels enable the concealment of encoded fluorescent information in specific three-dimensional shapes. This work presents innovative possibilities for designing and constructing advanced anti-counterfeiting systems.