Abstract
The purpose of this study was to develop a microcapsule-type self-healing coating system that could self-heal cracks and then maintain the healed state even upon crack expansion. Mixtures consisting of a photoinitiator and two methacrylate components, bismethacryloxypropyl-terminated polydimethylsiloxane (BMT-PDMS) and monomethacryloxypropyl-terminated PDMS (MMT-PDMS), were transformed into viscoelastic semi-solids through photoreaction. The viscoelasticity of the reacted mixtures could be controlled by varying the mass ratio of the two methacrylates. Through a stretchability test, the optimal composition mixture was chosen as a healing agent. Microcapsules loaded with the healing agent were prepared and dispersed in a commercial undercoating to obtain a self-healing coating formulation. The formulation was applied onto mortar specimens, and then cracks were generated in the coating by using a universal testing machine (UTM). Cracks with around a 150-μm mean width were generated and were allowed to self-heal under UV light. Then, the cracks were expanded up to 650 μm in width. By conducting a water sorptivity test at each expanded crack width, the self-healing efficiency and capability of maintaining the healed state were evaluated. The B-M-1.5-1-based coating showed a healing efficiency of 90% at a 150-μm crack width and maintained its healing efficiency (about 80%) up to a 350-μm crack width. This self-healing coating system is promising for the protection of structural materials that can undergo crack formation and expansion.
Highlights
A coating is usually applied to the surface of structural materials, such as concrete and steel, to protect it from corrosive substances including water, carbon dioxide, and chloride ions
Microcapsules loaded with the healing agent were prepared and were dispersed in the coating formulation to obtain a self-healing coating
In order to find the optimal composition of the healing agent, BMT-PDMS and MMTPDMS were mixed at various proportions and were polymerized (Scheme S1)
Summary
A coating is usually applied to the surface of structural materials, such as concrete and steel, to protect it from corrosive substances including water, carbon dioxide, and chloride ions. Damage to the protective coating can occur by microcracking or scratching, which causes the penetration of the corrosive substances through the damaged region. If a self-healing ability to repair the damage by itself is introduced into the protective coating, it can effectively protect the materials from deterioration. Self-healing coating technology can contribute to the extension of the material’s lifetime, the reduction of maintenance expenses, and the enhancement of public safety [1,2,3]. Microcapsule-type self-healing protective coatings have been developed extensively by incorporating microcapsules loaded with a variety of healing agents [4]. When the self-healing coating is damaged, the microcapsules in the damaged region rupture, and the healing agent is released. In most cases of previous studies on microcapsule-type self-healing coatings, the released healing agent chemically transformed into a hard solid
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
