Semifluorinated/hydrogenated alkylthiol thin films:: A comparison between disulfides and thiol binary mixtures

Self-assembled monolayers composed of disulfides with asymmetric functional groups (A-S-S-B) have been investigated on gold surfaces. The two coexisting functional groups, A and B, are linear hydrocarbon and semifluorinated hydrocarbon chains. Mixtures of two thiols with the same corresponding functional groups have also been investigated for comparison. The absence of island formation in disulfide-based SAMs supports the premise that not only are the S-S bonds intact in the solution during the self-assembly process, but that the adsorbed molecules also have a small lateral diffusion constant. Results from contact angle, FTIR, Raman, and XPS measurements are supportive of this conclusion.