Polymer nanocomposites as industrially useful corrosion inhibitors: Recent developments

Corrosion is defined as deterioration of metallic materials (metals and alloys) and their properties by the electrochemical reactions with the constituents of surrounding environments. Corrosion is a damaging and costly problem for both developed and developing countries including Australia, Japan, Germany, Kuwait, United States, China, Sweden, and India. According to national association of corrosion engineers (NACE), recent global annual cost of corrosion is approximately US $2.5 trillion which constitute approximately 4.2% of the world’s gross domestic product (GDP). In India annual cost of corrosion is approximately US $70 billion. The cost of corrosion can be minimized up to 15%-35% using available corrosion control measures such as materials selection, cathodic protection, surface coating, and corrosion inhibitors. Application of surface coating and solution phase corrosion inhibitors are most important, efficient, profitable, and easy methods for corrosion protection because of their cost-effective synthesis, high protection efficiency, and ease of application. Recently polymer nanocomposites (PNCs) are gaining particular attention in numerous fields of science, engineering, and technology. One of the greatest applications of PNCs that have attracted significant attention in recent times is in surface coating and solution phase corrosion inhibition of several metals and alloys. Both natural and synthetic polymers have been extensively used as effective corrosion inhibitors because of their high availability, environmental friendliness, and high protection ability. Generally high protection efficiency of the polymers results due to their high surface areas and numerous adsorption centers that offer strong intermolecular interactions between metallic surface and the polymers. However, use of pure natural and synthetic polymers is limited because of their moderate corrosion inhibition effectiveness and limited solubility. Therefore several attempts have been made in the past for copolymerization to improve the effectiveness of the polymers through synergistic effect. Recently attempts have been made for the incorporation of nanosized inorganic materials into the polymer matrix to improve the corrosion inhibition effectiveness of the polymers. The PNCs can be synthesized using ex situ or in situ chemical or electrochemical protocols. Several PNCs have been used as effective solution phase corrosion inhibitors and surface coatings. Present chapter deals with the collection of reports available on PNCs as solution phase corrosion inhibitors and anticorrosive surface coatings.