Interfacial friction of ethanol-water mixtures in graphene pores

The interfacial friction of fluid within nanoscale pores is important to nanofluidic devices and processes. Herein, molecular dynamics simulations have been used to study the interfacial flow resistance of ethanol-water mixtures confined within graphene-based nanochannels. The friction coefficients of the mixtures were investigated by considering the effects of slit pore width and mixture composition. The simulated results show that the flow friction coefficient is sensitive to the graphene slit pore size for ethanol-containing solution systems. In particular, the mixture composition has a significant impact on the friction coefficients for the mixture in 7-10 angstrom nanoslits, while the composition dependence of friction coefficients becomes weak at larger pore widths. In addition, qualitative theoretical analysis has been carried out to reveal the molecular origin of mixture friction behavior. The ethanol-wall interaction accounts for the major role on the mixture friction coefficients. The changing behavior of mixture friction coefficient is caused by the joint effects from the interfacial ethanol density and the potential energy barrier felt by ethanol molecules.