Programmable photo-responsive self-healing hydrogels for optical information coding and encryption

In this study, we proposed programmable photo-responsive self-healing hydrogels containing polyacrylamide (PAM), polyacrylic acid (PAA), poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA), ammonium molybdate (Mo7), and 7–2(acryloyl hydroxypropyl)-4-methyl-coumarin (AHPMC). Because of the electrostatic interaction of PAA and PDMAEMA, the hydrogel demonstrates good self-healing properties. Moreover, we introduced Mo7 and coumarin derivative in the hydrogel, respectively, which endows the hydrogel photo-responsive properties. Under the control of UV light, PAM-AD/Mo7 hydrogel with photochromic behavior could turn atrovirens, and PAM-AD/AC hydrogel with photoluminescent properties could emit blue fluorescence. In contrast, PAM-AD hydrogel possesses no photo-responsive behavior. Based on the self-healing and photo-responsive properties of the hydrogels, the three hydrogel blocks could be programmed and healed as a whole combination. In addition, we demonstrated the application of the hydrogel in optical information coding and encryption, which possesses good information coding and encryption effect. Therefore, the photo-responsive self-healing hydrogel may have potential applications in flexible information display and encryption fields.