On the protective action of 1,2,3-Benzotriazole derivative films against copper corrosion

The inhibiting effects of 1,2,3-benzotriazole (BTA), 5-methyl-BTA C1-BTA), 5-butyl-BTA (C4-BTA), 5-hexyl-BTA (C6-BTA) and 5-dodecyl-BTA (C12-BTA) films on the corrosion of copper in 3.5% NaCl (pH = 7 and 2.5) were evaluated from polarization curves and EIS spectra. The characteristics of the inhibitor film were investigated by means of wetting tests and XPS analysis. The tested compounds (almost insoluble C12-BTA excepted) produce films able to inhibit the oxygen reduction process depending on the alkyl chain length, but only C6-BTA film succeeds in hindering copper oxidation reaction, even in acid NaCl. the protective action expecially exerted by C6-BTA film should be related to the hydrophobic effect of the alkyl chain, rather trhan to an electron-releasing inductive stabilisation effect