A novel self-healing coating with mechanically-triggered self-reporting properties: Color and fluorescence dual damage indications

Smart coatings with self-reporting and self-healing functions are essential to prolong their service life. In this work, a novel strategy was proposed to fabricate a dual-function coating with both mechanically triggered self-reporting ability and shape memory effect activated self-healing function. Polyurethane/poly-(urea-formaldehyde) microcapsules containing 2′,7′-dichlorofluorescein (DCF) were incorporated into the shape memory epoxy polymer (SMEP) coatings, and the molar ratios of curing agent and epoxy monomer were adjusted to modify the residual amino groups in the coating so as to strengthen both the self-reporting and self-healing performances. Once the coating was mechanically damaged, DCF would release from the ruptured DCF@PU/UF microcapsules and react with the residual amino groups in the coating to illustrate prominent red color. Even with a topcoat of polyurethane varnish or black paint, yellow fluorescence signals of DCF could be facilely observed upon ultraviolet light irradiation. For the self-healing performance, the high mobility of polymer networks endowed the coating with shape memory effect to recover the original shape and the barrier property. This strategy exhibits excellent potential to prolong the service lifetime of smart coatings.