Preparation and characterization of damage indication and self‐healing microcapsules for surface micro‐cracks in mortar coating

Abstract

AbstractA mortar coating with damage indication and self‐healing properties based on microcapsules was proposed. The self‐healing microcapsules were synthesized by in‐situ polymerization method using urea formaldehyde resin as wall material and epoxy resin as core material. The damage‐indicator microcapsules with leuco dye crystal violet lactone as core material and polymethyl methacrylate as wall material were fabricated by solvent evaporation method. It was confirmed that after the core material was encapsulated, the heat resistance was improved. Through the particle diameter analysis of the microcapsules fabricated at diverse emulsifier contents and stirring speeds, it can be found that the microcapsule particle size decreased with increasing the emulsifier content and stirring speed. When cracks on the surface of the mortar coating were artificially fabricated, the damage‐indicator microcapsules can effectively highlight the surface cracks in blue for further manual repairs. The cured epoxy resin was found through the scanning electron microscope observation and element detection of the crack section. This indicated that the self‐healing microcapsules can fill micro‐cracks, thereby slowing down the development speed of cement‐based material cracks. This study provides a new method to detect and self‐heal surface micro‐cracks in mortar coating.