Advances in Linseed Oil-Filled Microcapsules for Self-Healing Coatings: Preparation, Characterization, Healing Mechanisms, Performance and Future Perspectives

Abstract

Drying oils such as linseed oil are interesting the attention of researchers not only as paint protection but also as self-healing components in smart coatings for corrosion protection. Linseed oil due to the fast-drying properties when they contact oxygen from the atmosphere. The encapsulation method is a quick and easy way to sanctuary their properties, facing many challenges in achieving stable oil-in-water emulsions. Linseed oil filled urea-formaldehyde microcapsules with various sizes were prepared via in-situ polymerization. To recognize the healing performance of linseed oil as a healing agent and the development of corrosion processes underneath the healed area, long term corrosion performing of scratched epoxy-based coating samples containing microcapsules. This review paper summarizes recent accomplishments in encapsulating linseed oils, tackling their high viscosity by changing process parameters (stirring speed, homogenization/ultrasonic step, use of different emulsifiers, etc.). This review paper also delivers a cheap and feasibility analysis for the industrial application of drying oils in self-healing coatings for corrosion protection. Corrosion test results showed that although linseed-oil can significantly improve the corrosion performance of the damaged coating in short-term however it rapidly decreases with time and hence this should be taken into account in designing of microcapsule’s core composition.