Intrinsic structure of hydrophobic surfaces: the oil-water interface.
We investigate the water-oil interface using molecular dynamics simulations of realistic models of alkanes and water. The intrinsic density profiles are computed using a methodology that removes the smoothing effect of the capillary waves. We show that at 300 K the intrinsic width of the gap separating the oil and water phases spans little more than one water molecule diameter, and undergoes very weak short-ranged fluctuations, indicating that the water-oil interface is a rigid molecular structure at ambient temperature. Only near the drying transition (above 500 K for dodecane), the gap features uncoupled fluctuations of the oil and water surfaces, as expected in a typical drying structure. We find that the intrinsic structure of water next to the oil phase is remarkably similar to the bare water-vapor interface.
Bresme
Fernando
F
Department of Chemistry, Imperial College London, London, United Kingdom. f.bresme@imperial.ac.uk
Chacón
Enrique
E
Tarazona
Pedro
P
Tay
Kafui
K