Unlocking Chemically Encrypted Information Using Three Types of External Stimuli

Abstract

Encryption is critical to information security; however, existing chemical-based information encryption strategies are still in their infancy. We report here a new approach to chemical encryption involving a supramolecular gel QR (quick response) code with multiple encryption functions. Three color "turn-on" supramolecular polymer gels, <b>G1</b>-<b>G3</b>, were prepared that produce pink, purple, and yellow colors when subject to treatment with acetic acid vapor, UV light, and methanolic FeCl₃, respectively. As the result of hydrogen-bonding interactions at the gel interfaces, the three gels can be assembled to produce gel <b>G4</b>. Engraving a QR code pattern onto <b>G4</b> then gave gel <b>G5</b>. When one or two stimuli are applied to the individual pieces corresponding to the QR engraved versions of the gels <b>G1</b>-<b>G3</b> making up <b>G5</b>, a complete scannable pattern is not displayed, and the stored information cannot be recognized. Only when three different stimuli are applied at the same time does <b>G5</b> give a complete recognizable pattern allowing the stored information to be retrieved. This strategy was applied to the decryption-based opening of a coded lock.