Nanodiamond loaded with corrosion inhibitor as efficient nanocarrier to improve anticorrosion behavior of epoxy coating

In the present study, thermally oxidized nanodiamond (OND) was first modified non-covalently with dodecylamine (DDA) as corrosion inhibitor. In this respect, reactive primary amine of DDA molecule with high isoelectric point (IEP) could interact easily with negative charge carboxylic acid groups of OND. Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) proved that OND nanoparticle was successfully functionalized by DDA up to approximately 5 wt% grafting contnet. Both OND and dodecylamine modified OND (DND) were loaded in epoxy (EP)/polyamine hardener matrix at the same concentration of 1 wt% and applied on mild steel substrate. Morphology of EP-DND and EP-OND investigated by field emission-scanning electron microscopy (FE-SEM) suggested well nano dispersion of DND in EP matrix. A detailed electrochemical impedance spectroscopy (EIS) analysis showed that low frequency impedance of EP-DND after 30 days immersion in 3.5 wt% NaCl solution is at least one order of magnitude higher than EP-OND and pure epoxy. Such superior corrosion protection behavior was associated to effective barrier properties of EP-DND against corrosive species caused by well dispersion of DND and efficient interaction within epoxy matrix as well as pH responsive release of DDA as corrosion inhibitor from nanodiamond surface. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.