Atomistic insight into the lubrication of glycerol aqueous solution: The role of the solid interface-induced microstructure of fluid molecules

Molecular dynamics simulations are performed to investigate the solid surface-induced microstructure and friction coefficient of glycerol aqueous solutions with different water contents confined in graphene and FeO nanoslits. Results show that the friction coefficient of glycerol aqueous solutions confined in both nanoslits presents similar nonlinear variation tendencies with increasing water content, but their lowest value and the corresponding water contents differ. Distinctive microstructures of the near-surface liquid layer induced by surfaces with different hydrophilicity are responsible for their difference in lubrication. The sliding primarily occurs at the solid–liquid interface for the hydrophobic graphene nanoslit owing to almost the same velocity difference in fluid molecules. By contrast, the sliding mainly occurs at the liquid–liquid interface for the hydrophilic FeO nanoslit because of the large velocity difference in fluid molecules. The weaker the interaction force at the sliding position, the lower the friction coefficient.