Coating that self-reports cracking and healing using microcapsules loaded with a single AIE fluorophore

A crack and crack healing were both detectable with a microcapsule-based dual-reporting self-healing coating system developed using a single aggregation-induced emission (AIE) fluorophore, (2Z,2′Z)-3,3′-(2,5-bis(diphenylamino)-1,4-phenylene)bis(2-(4-fluorophenyl)acrylonitrile) (DPA-PPV-F). This selected and synthesized single AIE dye was tested for changes in its fluorescence color and fluorescence intensity following a solution/solid-state phase change. These unique AIE-fluorophore-embedded microcapsules were successfully synthesized, and a crack/healing dual-reporting self-healing system with a top coating and an epoxy matrix resin was prepared. The prepared self-healing coating system was indicated by optical microscopy and scanning electron microscopy (SEM) after a scratch was created with a razor. The self-healing coatings showed red fluorescence with weak intensity immediately after being scratched, and the fluorescence color changed from red to orange as healing occurred via photocuring. The fluorescence intensity also dramatically increased at the healing region soon after the scratch was inflicted. The fluorescence color changed from red to orange according to the crack/healing process, and the fluorescence intensity also dramatically increased.