Molecular Dynamics Study of a Surfactant Monolayer Adsorbed at the Air/Water Interface.

A constant volume and temperature (NVT) molecular dynamics (MD) simulation has been carried out to investigate the properties of a monolayer of monododecyl hexaethylene glycol (C12E6) adsorbed at the air/water interface at a surface coverage corresponding to that at its critical micelle concentration (55 Å(2) per molecule). The simulated results have been found to agree reasonably well with available experimental data and with other simulation studies. The study shows that the long polar headgroups of the surfactants are more tilted toward the aqueous layer due to strong interaction between them and water. It has been shown that the surfactant monolayer strongly influences the translational and rotational mobility of interfacial water molecules. A drastic change in the dipolar reorientational motion of water molecules in the aqueous layer is observed with a small variation of distance from the surfactant headgroups.