Self-healing coatings based on poly(urea-formaldehyde) microcapsules: In situ polymerization, capsule properties and application

Abstract Protective coating failure can lead to excessive substrate wear increasing the need for maintenance. Polymeric microcapsules loaded with a healing agent can offer self-healing properties when embedded to a coating, repairing the microcracks produced. Epoxy loaded microcapsules with a poly(urea-formaldehyde) shell were successfully prepared within the current study, using in situ polymerization. Microcapsules were obtained as colorless free-flowing powder with a diameter ranging from 37 to 66 μm and high encapsulation efficiency (up to 75%). Microcapsule characteristics, such as morphology, particle size, encapsulation efficiency, thermal stability, were correlated to in situ polymerization conditions, and efficiently induced self-healing ability to an alkyd-based coating.