Application of polymer composites and nanocomposites as corrosion inhibitors

Corrosion commonly defined as the deterioration of a material (usually a metal) or its properties because of a reaction with its environment is a global problem. NACE International, The Corrosion Society, estimates that global corrosion costs can be about 3-5% of GDP or GNP. Methods commonly adopted to combat corrosion include coatings and linings, cathodic protection, materials selection and corrosion inhibitors. Corrosion inhibitors are chemicals that, when present in very low concentrations, retard corrosion. Corrosion inhibitors form a layer over the metallic substrate and protect the metal from corrosion, thereby enhancing the life of the metal. Polymers, both naturally occurring and synthetic have been tested for metal corrosion inhibitors as replacement for the toxic inorganic and organic corrosion inhibitors. Interest in polymers stems from their availability, cost effectiveness, and eco-friendliness in addition to the inherent stability and multiple adsorption centers. However, it is found that most polymer materials studied are moderate corrosion inhibitors. Several attempts such as copolymerizing, addition of substances that exert synergistic effect, cross linking, blending, and most recently incorporation of inorganic substances in nano size into the polymer matrix have been made to improve the inhibition ability of polymers. Composites are materials consisting of two or more chemically distinct constituents on a minutescale, having a distinct interface separating them, and with properties which cannot be obtained by any constituent working individually. The production of composite materials is either by ex-situ or in-situ formation through chemical synthesis although electrochemical method had been used recently. The application of polymer composites and nanocomposites as anticorrosion materials have shown promising results and are believed to form metal chelate which could barricade metal surfaces from corrosive agents. In this chapter, the application of polymer composites and nanocomposites as corrosion inhibitors for different metal substrates in different corrosive media is explored.