Water/organic liquid interface properties with amine, carboxyl, thiol, and methyl terminal groups as seen from MD simulations.

Abstract

Molecular dynamics simulations were performed to study structural and dynamic properties of polar butanamine/water/butanamine, pentanoic acid/water/pentanoic acid, butanethiol/water/butanethiol, and nonpolar pentane/water/pentane systems. The mass density profiles along the interface normal to the organic liquid/water system, the difference in the local structure of H O molecules in bulk and in the vicinity of interface, as well as the diffusion behavior of water molecules at the interface with above-mentioned organic liquids have been investigated. Our MD simulation has shown that the diffusion of water molecules across the water/organic liquid interface is influenced by the hydrogen bonds between water molecules and the terminal groups of organic liquids. It was found that the loss of the hydrogen bonds in the nonpolar organic liquid leads to a decrease in the value of the normal component of the diffusion coefficient , while the tangential diffusion coefficients, both and , increase.