Concentration Effect on the Hydrogen-Bond Strength between Small Molecules at the Oil/Water Interface: Application to Coarse-Grained Model Development

Abstract

Oil-water interface are ubiquitous in nature and are particularly important in biology as a simplified model for the membrane-water system. This model is used to study the transfer of biological molecules across the membrane. We are interested in the thermodynamic behavior across the bulk oil, oil/water interface and the bulk water at varying alcohol concentrations. In addition to all atom simulations, we also performed coarse-grain simulations using the SDK model. In oil/water interface, the alcohols behaves differently at different concentration. Lower concentrations of alcohol prefers associative behavior but at higher concentration it becomes less associative. All of the simulations and free energy calculations were carried out with NAMD version 2.9 and for coarse-grain we used LAMMPS. System were described with the CHARMM27 force field. The TIP3P model was used for water. The results we obtained are compared with the existing theoretical and experimental findings.