Corrosion Protection Of Copper By Self-Assembled Monolayers Modified In Aqueous Micellar Solution

Self-assembled monolayers (SAMs) have been widely used in the corrosion protectionof copper. Because organic solvents are usually used in the assembly of SAMs,environmental problems are generated. Therefore, it is necessary to find substitutes for theorganic solvents so as to obtain eco-friendly films. Aqueous micellar solution can be usedto generate hydrophobic cores that dissolve alkanethiols. Such water-borne SAMs havedenser molecular packing than those prepared in organic solvents, attributing tohydrophobic interactions between alkyl chains during self-assembly.In this paper, dodecanethiol (DT) SAMs on copper were formed using aerated anddeaerated aqueous micellar solutions of cetyltrimethyl ammonium bromide (CTAB),respectively. Scanning electronic microscopy (SEM), atomic force microscopy (AFM),X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transforminfrared spectroscopy (ATR-FTIR), electrochemical impedance spectroscopy (EIS),polarization curves and cyclic voltammograms were used to investigate the structure andinhibition effects of these SAMs.Results show that the water-borne DT SAMs are compact and well-orientated withhigh coverage and few defects. SAM formed in the aerated solution have higher quality andbetter protection efficiency when compared to SAM formed in the deaerated solution. Afterimmersion in3%NaCl solution for7days or exposure to air for30days, the water-borneSAMs still protect copper well and SAM formed in the aerated solution performs better toinhibit corrosion from Cl－and air. The superiority of SAM formed in the aerated solutionis attributable to synergistic effects among the DT SAM, multimolecular complexes ofalkanethiols and CTAB-Cu (I) complexes.