Synthesis and characterization of poly(urea-formaldehyde) microcapsules containing linseed oil for self-healing coating development

In this study, linseed oil was successfully encapsulated in poly(urea-formaldehyde) (PUF) shell via in-situ polymerization to achieve a microcapsule-based self-healing coating. A set of techniques including Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), optical microscope, and scanning electron microscope (SEM) were used to completely characterize the synthesized microcapsules. The effects of the molecular weight of poly(vinyl alcohol) (PVA) stabilizers, stir rates, and reaction temperatures on the property of microcapsules were investigated. Micro-computed tomography (micro-CT) showed a uniform distribution of microcapsules inside the coating matrix. The stable microcapsules with the high content of core materials ensured the self-healing function. By observation from SEM, the self-healing coating showed excellent healing performance upon artificial cracks comparing to the blank epoxy coating.