Towards smart self-healing coatings: Advances in micro/nano-encapsulation processes as carriers for anti-corrosion coatings development

Smart materials based on the self-healing concept are used in different advanced applications such as buildings, batteries and coatings. The development of these materials follows two scenarios: the development of materials with intrinsic self-healing properties, or the preparation of extrinsic self-healing materials containing adds such as microcapsules filled with healing agents. Currently, the extrinsic self-healing technique is the most investigated and applied. Microcapsules preparation is a key step for extrinsic self-healing materials development. For this purpose, a variety of micro/nanoencapsulation processes have been reported. This review aims specifically to present recent advances and a critical overview of the encapsulation processes used to develop microcapsules for anticorrosion self-healing coatings. For each encapsulation method, the advantages and limitations are evaluated. The challenges facing the micro/nano encapsulation processes, recent proof-of concepts and future trends are also discussed.