Self-assembled monolayers of alkanethiols on copper provide corrosion resistance in aqueous environments

Alkanethiols adsorb onto copper surfaces and form densely packed monolayer films that inhibit corrosion of the underlying copper substrate. The performance of these self-assembled monolayers are insensitive to the presence of water as they provide equal levels of protection in both dry and humid oxygen-containing atmospheres. This observation suggests that the monolayer films provide a barrier against water penetration, as the corrosion of untreated copper samples is much more rapid in the presence of water. In these applications, longer-chained adsorbates - C18H37SH and C22H45SH - provided the greatest levels of protection. Monolayers formed from these adsorbates were also effective as barrier layers toward oxidation when the samples were immersed in oxygen-saturated water for over 1 week. These densely packed, chemisorbed layers maintained their level of performance during the weeklong exposure without the need for adding corrosion inhibitor molecules to the contacting water phase. Preliminary experiments show that bilayer assemblies formed from the sequential adsorption of HS(CH2)(22)OH and CH3(CH2)(17)SiCl3 provide a stable molecular architecture for forming thicker, robust coatings on the copper surface; however, the use of chlorine-containing reagents in the formation of this assembly results in defects that seriously impede the inhibition properties of the layers.