Effects of water vapour on 2-mercaptobenzothiazole corrosion inhibitor films deposited on copper

The effects of water on 2-mercaptobenzothiazole (2-MBT) film pre-formed on copper at low pressure and room
temperature was investigated in situ by X-ray photoelectron spectroscopy. Upon exposure to water vapour at
5 × 10^-6 mbar, the 2-MBT molecules not directly bonded to copper desorb, until only one monolayer remains
adsorbed. Further exposure leads to cleavage of the bond between exocyclic sulphur and copper, whereas nitrogen
remains bonded to copper. Dissociative adsorption of water is observed, without copper oxidation for
exposure up to 3 × 10⁶ L. This work brings new molecular scale insight into corrosion inhibition mechanisms in
water-containing environments.