Dual encryption of digital information in a tough fluorescent hydrogel

Hydrogels capable of shape-morphing and/or fluorescence modulation have practical significance in the field of anti-counterfeiting, while tough hydrogels with tunable fluorescence for multi-level encryptions have been rarely explored. Herein, we report a hydrogel P(DAE-co-AAc) for dual information encryption. The hydrogel is prepared by copolymerization of photoresponsive diarylethylene and acrylic acid, and it exhibits tunable mechanical properties and fluorescence. The soft hydrogel becomes tough when exposed to UV irradiation which induces dimerization of diarylethylene units, and thus information can be concealed by a folding-and-irradiation process. Tunable fluorescence upon irradiation enables photolithography for pattern encryption. Benefitting from reversible photo-decrosslinking, shape and emission recoveries can be realized, making the encryption material recyclable. We believe this work will be inspiring for the design of smart materials for information encryption.