Erasable, Rewritable, and Reprogrammable Dual Information Encryption Based on Photoluminescent Supramolecular Host–Guest Recognition and Hydrogel Shape Memory

Abstract Information encryption technologies are very important for security, health, commodity, and communications, etc. Novel information encryption mechanisms and materials are desired to achieve multimode and reprogrammable encryption. Here, a supramolecular strategy is demonstrated to achieve multimodal, erasable, reprogrammable, and reusable information encryption by reversibly modulating fluorescence. A butyl‐naphthalimide with flexible ethylenediamine functionalized β ‐cyclodextrin (N‐CD) is utilized as a fluorescent responsive ink for printing or patterning information on polymer brushes with dangling adamantane group grafted on responsive hydrogels. The photoluminescent naphthalimide moiety is bonded to β ‐CD and entrapped in the cavity. Its fluorescence is highly weakened in β ‐CD cavity and recovers after being expelled from the cavity by a competing guest molecule to emit bright green photoluminescence under UV. Experiments and theoretical calculations suggest π – π stacking and ICT as the primary mechanism for the naphthalimides assembly and fluorescence, which can be quenched through insertion of conjugated molecules and recover by removing the insert. Such reversible quenching and recovering are used to achieve repeated writing, erasing, and re‐writing of information. Supramolecular recognition and hydrogel shape memory are further combined to achieve reversible dual‐encryption. This study provides a novel strategy to develop smart materials with improved information security for broad applications.