Abstract
Corrosion protection activities of thin films formed on iron by electrochemical polymerization of organic compounds were studied by electrochemical measurements, spectroscopy, and chemical analysis. Pyrrole, aniline, phenol and their derivatives were polymerized by electrooxidation on an iron disk electrode in nonaqueous solvents, and vinyl compounds and organic halides by electroreduction. Corrosion protection effects of the films thus formed were examined by the polarization measurements for the electrodes with rotating at 500rpm in an aerated aqueous 0.5M Na2SO4 solution (pH7). Among all of the examined compounds, α, α′-dibromo-p-xylene afforded the most protective film when it was cathodically electropolymerized in the presence of oxygen. The role of oxygen for the corrosion protection was investigated by the comparison of the films prepared from α, α′-dibromo-p-xylene between in air and under nitrogen, by chemical analysis, polarized reflection IR spectroscopy, and scanning electron microscopy. It was found that oxygen was reduced to form O2-· and this radical was involved in the polymerization reaction to result in the construction of packed polymer structure containing C=O and C-O moieties besides the main chain of (-CH2-C6H4-CH2-)n.
