Experimental and computational study of thermally-driven phase separation of mixed thiol SAMs on Au(111)*

Mixed self-assembled monolayers with two or more distinct components and have been shown experimentally to undergo phase separation. Control over phase separation and composition of mixed monolayers would allow one to “tune” the properties of the surface, like thermal conductivity, wetting/capillary behavior, or interactions with complex molecules like proteins. The present reseracrh concerns whether it is possible to modulate domain morphology and composition by varying the cooling rates during SAM formation. Both experiments and simulations of phase separation are carried out. This synergy will allow us to reduce the number of experiments necessary to control over the domain formation of the SAMs.  Through AFM characterization, we have seen experimentally that there is a correlation between SAM domain size, morphology, and the rate of cooling. We also have developed a numerical model that introduces temperature dependence into the Cahn-Hilliard equation to model domain formation of SAMs with a decaying temperature. Here we present and compare current simulations and experiments.