Chapter 6 - Inhibitor-encapsulated smart nanocontainers for the controlled release of corrosion inhibitors

Abstract

Corrosion of metals/materials is an expensive material science issue, which has originated since the day of metal invention. Numerous methods were developed, and still many serious research works are being in progress for corrosion mitigation. Corrosion inhibitor usage is a common practice over industries because of its ease of applications and effectiveness. A large number of chemicals, which include organic molecules with heteroatoms (O, N, and S)/π electronic cloud, inorganic complexes, rare earth metals, and green products derived from plants, were positively identified as corrosion inhibitors for various corrosive environments. Protective coatings also play a major role in metal protection, while under aggressive/extreme corrosive environments, efficiency of protective coating is not sufficient. In these conditions, addition of corrosion inhibitors along with protective coatings enhanced the metal protection effectively. However, direct blending of coatings with corrosion inhibitors was found ineffective, which leads to innovative method of using a carrier (nanocapsule/container) to encapsulate the corrosion inhibitor. Nanocontainers have a great potential to deliver corrosion inhibitors where the corrosion damage initiated. Hence, the current scenario on corrosion inhibitors research is to develop a “smart coating” for metal protection, which comprises protective coatings and “nanocontainer,” loaded with corrosion inhibitor. Various nanocontainers, viz., halloysite nanotubes, titania nanocontainers, mesoporous silica nanocontainers, and polyelectrolyte shell, were successfully identified and being developed for “smart coating” applications. Advancement of “smart coating” application extends its metal protection for oil/gas pipelines, cooling towers, marine environments, and reinforced concrete. This chapter deeply discusses the origin of nanocontainers, various literatures of nanocontainers loaded with corrosion inhibitor, and their mode of application in smart coatings.