Ultraviolet encryption information storage using hydrophobic poly(ε-caprolactone)/carbon quantum dot composite film

Abstract

Luminescent poly(ε-caprolactone)/nitrogen-doped carbon quantum dots (PCL/N-CQDs) film with the function of information protection and encryption was realized based on the fluorescent N-CQDs. The N-CQDs were synthesized from citric acid with urea as a dopant for the enhancement of fluorescent properties. The facilely prepared composite film retained the hydrophobic nature of PCL and achieved the enhanced mechanical property. The appropriate crystallization temperature and degree of crystallinity of PCL provide the film with opaque characteristics at room temperature, rendering it an ideal carrier for carrying information. The information encryption and decryption are achieved through ionoprinting technique, exploiting the ability of Fe3+ ions to quench the fluorescence of N-CQDs, allowing for the encryption of designed information on the film’s surface. With its opaque, hydrophobic, and photoluminescent properties, the PCL/N-CQDs composite film holds significant promise for applications in information encryption.