Corrosion Protection of Poly(aniline-co-N-ethylaniline)/ZnO Nanocomposite Coating on Mild Steel

A copolymer of aniline (AN) and N-ethylaniline (EA), namely Poly(AN-co-EA) and its composite with ZnO nanocomposites, Poly(AN-co-EA)/ZnO were synthesized by chemical oxidative polymerization using ammonium persulphate as an oxidant. The synthesized compounds were characterized by FTIR, XRD, SEM and electrical conductivity techniques. The synthesized compounds were dissolved in N-methyl-2-pyrrolidone (NMP) and were casted on mild steel (MS) specimens using 10 % epoxy resin as a binder. The adhesion properties of the copolymer and nanocomposite coatings were also tested. The anticorrosion behaviour of coated MS was investigated in 0.1 M HCl, 5 % NaCl solution, distilled water and open atmosphere by performing immersion test, open-circuit potential measurements, potentiodynamic polarization measurements, electrochemical impedance spectroscopy and atmospheric exposure test. Surface morphology of the coated steel prior to and after 30 days immersion in corrosive solution was evaluated using SEM. The nanocomposite coating showed excellent protection against MS corrosion; the protection efficiency (PE) varied in the range of 89-96 % after 30 days of immersion. The incorporation of ZnO nanoparticles improved the anticorrosion properties of Poly(AN-co-EA) copolymer in all corrosion media subjected to investigation.