Photochromic Polyurethane Coatings with Cross-Linked Structure and Self-Healing Behavior Based on the FRET Effect.

Intelligent fluorescent coatings have received widespread attention in the encryption technique field such as anti-counterfeit and information coding, while the traditional fluorescent coatings are easy to be damaged by external force and difficult to be repaired, which often limits the applications. In this study, the fluorescent and self-healing smart anti-counterfeit coatings were prepared after rational molecular design. Two polymers containing fluorescent groups, including polyurethane containing the anthracene (AN) side group and polyimide containing the naphthalenediimide (NDI) structure were synthesized to realize multiple color changes with fluorescence through simply blending. Due to the overlapping fluorescence spectra of the groups in the composites, enabling the fluorescence resonance energy transfer effect (FRET), the coating with different group ratios exhibits tunable blue, green, and red fluorescence under the same excitation light, providing diverse information for coating patterning. Moreover, as a result of the reversible photo-crosslinking and thermal de-dimerization properties of AN, the recording, erasure, and rewriting of the information on the surface pattern can be realized, and the fluorescent anti-counterfeit coatings exhibit excellent self-healing properties after cross-linking due to the FRET effect, which solves the problem of poor healing due to light cross-linking and ensures the stability and integrity of the coatings in the application. The preparation of fluorescent coating with cross-linked structure and self-healing behavior based on the FRET effect greatly expands the functional applications of traditional polyurethane materials, which is expected to be used for anti-counterfeiting pattern, optical information storage, fluorescent probes, and other fields. This article is protected by copyright. All rights reserved.