Combined Molecular Dynamics and Quantum Mechanics Study of Oil Droplet Adsorption on Different Self-Assembly Monolayers in Aqueous Solution

Abstract

In this paper, the dodecane is selected as the oil phase, and the adsorption behavior of an oil droplet on six self-assembled monolayer (SAM) surfaces in aqueous solution is investigated by a combined molecular dynamics and quantum mechanics method. First, the adsorption configuration of an oil droplet on these six surfaces is investigated, which indicates that the oil droplets spread on SAMs of −CH3, −OCH3, and −COOCH3 and detach from SAMs of −NH2, −OH, and −COOH. After that, the interactions of oil–SAM and water–SAM are calculated to rationalize the driving force controlling the conformational change of the oil droplet on various SAMs. Researched results suggest that the conformational change of the oil droplet is mainly driven by the interaction between water and SAMs. Finally, the mechanism of oil spreading or detachment behavior is discussed from the aspect of water property near the SAM, and calculated results show that the adsorption capability and dynamic property of interfacial water have a profo...