Epoxy loaded poly(urea‐formaldehyde) microcapsules via in situ polymerization designated for self‐healing coatings

Abstract Self‐healing systems are a next‐generation technology that can offer autonomous crack repair and increase the service lifetime of a protective coating. Polymeric microcapsules containing healing agents can be used in that perspective and exhibit significant potential. In the current study, poly(urea‐formaldehyde) microcapsules containing an epoxy healing agent as core material were successfully prepared using in situ polymerization. The effect of different process parameters was studied in respect to microcapsules' characteristics, that is, morphology, particle size, encapsulation efficiency and thermal properties. Spherical microcapsules with either smooth or rough surface were obtained with a size ranging from 90 to 165 μm, controlled by the stirring rate during the emulsification stage. The encapsulation efficiency varied between 65–77% with no significant dependence on the process conditions. Finally, the stability of the microcapsules during storage was investigated at different conditions.