Corrosion performance of waterborne epoxy coatings containing polyethylenimine treated mesoporous-TiO2 nanoparticles on mild steel

Waterborne epoxy coatings were modified by adding mesoporous-TiO2 nanoparticles (meso-TiO2). In order to achieve proper dispersion of meso-TiO2 in the epoxy-based coating and make possible chemical interactions between meso-TiO2 and polymeric coating, meso-TiO2 was treated with polyethylenimine (PEI) of various molecular weights. Corrosion performance of mild steel coated specimens was investigated employing electrochemical impedance spectroscopy (EIS) and salt spray test. Coatings with meso-TiO2/PEI (600 molecular weight) possessed the best corrosion performance among the coating specimens. The EIS results showed that the resistance value of coating with meso-TiO2/PEI (600 molecular weight) was above 9.87 x 10(7) Omega cm(2) which was higher than neat epoxy coating. Possible chemical interactions between polymeric matrix and treated nanoparticles caused high barrier properties and high degree of cross-linking. (C) 2015 Elsevier B.V. All rights reserved.