Encapsulation of triethanolamine as organic corrosion inhibitor into nanoparticles and its active corrosion protection for steel sheets

Triethanolamine (TEA), a corrosion inhibitor for zinc and steel, was introduced into nano-sized particles as nanoreservoirs to increase longevity of inhibitive property and prevent degradation caused by direct addition of corrosion inhibitor into coating layer. TEA-incorporated nanoparticles with average particle size around 400–450 nm were successfully synthesized by sequential emulsion polymerization, occupying around 5% of total solid weight of particles during a neutralization process. Encapsulated TEA was released from the capsule inside when the pH level of environment became acidic or alkaline due to an acid–base interaction or ionization of seed material in specific conditions. In the corrosion tests, the encapsulated TEA decreased the corrosion rate of steel substrate owing to its adsorption on steel surface and the resistance of coating layer against corrosive environment was much higher and remained its resistance as immersion time increased when TEA was incorporated in coating layer in the encapsulated form. Based on the scanning vibrating electrode technique (SVET) result, anticorrosive ability of the encapsulated TEA seemed to improve due to the spontaneous passivation of exposed metal on the defected region of coated steel.