Visualization and monitoring of dynamic damaging–healing processes of polymers by using AIEgen-loaded multifunctional microcapsules

Abstract

The sensitive detection and dynamic monitoring of the structural health of polymers are crucial to increase their quality, reliability, and durability. Although a lot of effort has been devoted to the indication of static damaged and/or healed states of polymers, the simple, sensitive, and real-time monitoring of dynamic damaging–healing processes still remains challenging. In this work, a facile design strategy for multifunctional polymer coatings that can sensitively show their damaging–healing processes in an on-site, real-time, and full-field manner is demonstrated. By embedding UV-blocking microcapsules containing the diisocyanate solution of an aggregation-induced emission luminogen (AIEgen) into a polymer matrix, immediate turn-on fluorescence is observed upon damage, and dual-signal variations in both the fluorescence intensity and color can be clearly visualized during the dynamic healing process. These changes can also be readily and semi-quantitatively detected by using a fluorescence spectrometer and digital image correlation analysis. Such a high-contrast fluorescence change is achieved due to the collective effects of AIE and twisted intramolecular charge transfer of the luminogen. Benefiting from the multifunctional microcapsules, the composite polymeric coatings exhibit excellent photo-protective and water-proof performances in addition to the autonomous damaging–healing visualization capability, which are appealing to various practical applications.