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

Polymeric materials play an essential and ubiquitous role in modern societies, but they are inevitably damaged during service, which can lead to compromised performance or even direct failure. The sensitive detection and dynamic monitoring of the health states of polymers is thus crucial to increase their reliability, safety, and lifetime. Herein, a facile fluorescence-based approach that can achieve the nondestructive, on-site, real-time, full-field, and sensitive visualization and monitoring of damaging-healing processes of polymers is demonstrated. By embedding novel UV-blocking microcapsules containing a diisocyanate solution of aggregation-induced emission luminogens (AIEgens) into a polymer matrix, the damaged regions of the composite show turn-on fluorescence and dual signal changes in both fluorescence intensity and fluorescence color can be observed during the healing processes. The invisible information of the static health states and dynamic healing processes can be directly and semi-quantitatively visualized by naked eyes based on the collective effects of AIE and twisted intramolecular charge transfer. In addition to the autonomous damage-reporting, self-healing, and health indication functionalities, the microcapsule-embedded polymeric coatings possess excellent photo- and water-protection capabilities, which are appealing to various practical applications.