Solid Surface Induced Anisotropic Clustering in Ethanol-Cyclohexane Binary Liquids Studied by Molecular Dynamics Simulations

Molecular dynamics simulations were performed to investigate the interfacial liquid structure at the solid interface of a ethanol-cyclohexane mixture, a typical system with micro-heterogeneity in the liquid bulk. The degree of micro-heterogeneity was decreased, not only when the solid surface was hydrophilic as previously reported, but also when it was hydrophobic. However, the microscopic mechanism was different. The hydrophobic surfaces restricted the molecular orientation of ethanol, and hence, sterically suppressed the clustering of ethanol molecules in the in-plane direction. Molecular dynamics simulations were performed to investigate the interfacial liquid structure at the solid interface of the ethanol-cyclohexane mixture. The micro-heterogeneity was decreased, not only when the solid surface was hydrophilic as previously reported, but also when hydrophobic. The hydrophobic surfaces restricted the molecular orientation of ethanol, and hence, sterically suppressed the clustering of ethanol molecules in the in-plane direction.