3D Printed Hydrogels with Time/Temperature-Dependent Photoluminescence for Multi-information Dynamic Display

There is an urgent need to develop next-generation information storage and display materials to protect confidential information. Herein, we introduce the vat photopolymerization (VP) 3D printing technology with low-intensity visible light to fabricate two kinds of new fluorescent hydrogel-based information carriers in a green and efficient way. One of them affords the characteristics of time-dependent multicolor fluorescence and reversible photochromism, and the other features multifactor modulation character and temperature-dependent photoluminescence when doped with lanthanide ions. A 3D code-producing array constructed from these hydrogels is able to render dynamic information transformations on a time scale by controlling UV exposure and heating treatment. More importantly, a cryptographic matrix composed of these hydrogels makes the encrypted information only identifiable at a specific time in accordance with the sequence of photochromism; meanwhile, the information can self-erase after being read according to the fading behaviors upon exposure to air. The related works are still rare in the field of information encryption and decryption. We expect the VP 3D printing technology to guide the future intelligent manufacturing for fluorescent hydrogels; additionally, we hope that these two fluorescent hydrogels can serve as a new avenue for the future development of information storage and display materials.