A long-term stable and environmental friendly self-healing coating with polyaniline/sodium alginate microcapsule structure for corrosion protection of water-delivery pipelines

Recently, various self-healing materials have been proposed. However, there is a blank in the field of corrosion protection of water-delivery pipelines, because the self-healing performance is undesirable in the condition of water scouring and most of the encapsulated self-healing agents deteriorate the water environment during the self-healing process, rising the risk of human health damage. Aiming at solving the current problems, we successfully synthesize an environmentally friendly smart coating for corrosion protection of water-delivery pipelines. The coating contains a polyaniline shell and a sodium alginate core microcapsule structure and exhibits a hydrophobic surface, a steady thermo-stability, an acceptable tensile strength, and a good adhesion capability with carbon steel in a simulated water-delivery environment. From the experimental results, the coating exhibits a remarkable corrosion protection capability (99.9943%) after 50 days of immersion in corrosive medium. In addition, the scratch test indicates that the surface resistance recovers to 90% of the intact coating within 12 h, resulting from the formation of a sodium alginate/calcium alginate composite barrier layer in the defect region. Furthermore, no hazardous materials could be detected in the water after the coating was damaged, thus confirming its environmentally friendly characteristics.