Droplets of oil in water appear in our daily lives as food, pharmaceuticals and in the petrochemical industry (the by-product of the production of crude oil). The properties of oil droplets dispersed in water are primarily determined by the chemical nature of the interfacial region as a stable dispersion typically consists of nanoscopic oil droplet with a high surface-to-volume ratio.We have investigated the hidden interfacial region of nanoscopic droplets in water using vibrational Sum Frequency Scattering (SFS). The average water orientation on a neat oil-droplet/water interface is the same as the water orientation on a negatively charged interface. For the latter interface, the interfacial density of adsorbed SDS is at least one order of magnitude lower than at a corresponding planar interface. The oil alkyl chains are much stiffer than the surfactant chains, and exhibit an orientation predominantly parallel to the surface plane.

Nanoscopic oil droplets in water: Structure of water, surfactants, and oil

243rd National Meeting (2012)

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