Molecular Insights into the Effect of Temperature and Functional Groups on the Nonwetting, Prewetting, Partial Wetting, and Complete Wetting Transitions of Ethanol on Graphite

Adsorption of ethanol on pure and oxygenated graphite surfaces in the 120–425 K temperature range was conducted to microscopically investigate wetting transitions using a Grand Canonical Monte Carlo Simulation. At temperatures <120 K, ethanol displayed nonwetting on the pure graphite substrate. Interestingly, in the temperature range 120–159 K, it transitioned to prewetting and displayed partial wetting at higher temperatures (159–278 K). Complete wetting occurred at further temperatures (>278 K). On the isotherm, partial wetting had two vertical jumps to a complete monolayer (∼6 μmol/m²) and a second layer (∼14 μmol/m²) sequentially. The thin-to-thick film of prewetting had only one vertical jump to complete two layers simultaneously. When functionalized graphite was considered, nonwetting and prewetting of pure graphite at low temperatures (<120 and 120–159 K) could be transferred to partial wetting. According to the results of this study, the transition from prewetting to partial wetting occurs not only with higher substrate affinity but also at higher temperatures.