Fluorescent Organohydrogel with Thermal‐Induced Color Change for Anti‐counterfeiting

Comprehensive Summary Smart fluorescent patterns enable dynamic color variation under external stimuli, showing a much higher security level in the field of anti‐counterfeiting. However, there is still lacking of a simple and convenient way to achieve dynamic fluorescence changes. Herein, a fluorescent organohydrogel made up of a poly(N,N‐dimethylacrylamide‐co‐isopropylacrylamide) (p(DMA‐NIPAM)) hydrogel network and a poly(lauryl methacrylate) (PLMA) organogel network was fabricated via a two‐step interpenetrating technique. The former network bears naphthalimide moieties (DEAN, green fluorescent monomer) and the later contains 6‐acrylamidopicolinic acid (6APA, fluorescent ligand), leading to emitting green fluorescence. When Eu3+ was introduced and coordinated with 6APA, the organohydrogel displays red fluorescence, which can further emit yellow after applying thermal stimulus. Furthermore, by adjusting the proportion of comonomers, various organohydrogels can be obtained, which can be programmed and act as an effective platform for the encryption and decryption of secret information. Adopting two‐step interpenetrating technique, a heterogeneous fluorescent organohydrogel made up of a poly(N,N‐dimethylacrylamide‐co‐isopropylacrylamide) hydrogel network and a poly(lauryl methacrylate) organogel network has been fabricated. Response to the stimulus of heat with fluorescent color variation, the organohydrogel thus can be applied for anti‐counterfeiting.