Surface modification of copper with 2-dodecylpropane-1,3-dithiol: The key effect of the solvent

Self-assembly of alkanethiol on gold in various solvents (alkane, alcohol, etc) leads to monolayers with similar properties. However when the self-assembly is performed on copper substrates, the nature of the solvent has an effect on the properties of the monolayer. This phenomenon arises from the chemical interaction of copper with the solvent, which is not the case of gold. Ethanol is a solvent widely used for self-assembly, however some studies pointed out its negative effect due to its significant chemical reactivity towards copper and its ability to chemisorb on the surface. The aim of this work consists in a comparative investigation of 2-dodecylpropane-1,3-dithiol (or R(SH)2) in various solvents and its ability to form stable SAMs, densely packed and well ordered. Characterizations of the SAMs are carried out using X-ray photoelectron spectroscopy (XPS), polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) and cyclic voltammetry (CV).