Effect of Surface Freezing of Sodium Hexadecyl Sulfate - Hexadecanol Mixed Adsorbed film on OW Emulsion Stability.

Abstract

The adsorbed film of Sodium Hexadecyl Sulfate (SHS) at the dodecane - water interface showed a first-order phase transition to a surface frozen monolayer upon cooling by the lateral van der Waals attraction between their hydrophobic tails and those of hexadecanol (C16OH) incorporated from the dodecane phase. The surface freezing transition of the SHS - C16OH monolayer was then utilized to stabilize an oil-in-water (OW) emulsion. The obtained results were compared to those examined previously for the cetyltrimethylammonium chloride (CTAC) - C16OH surface frozen monolayer. The main conclusion of this study was that the interfacial density of SHS significantly increased at the surface freezing by the cooperative adsorption with C16OH which gave rise to a higher surface freezing temperature (35°C) compared to CTAC (25°C). The formation of the surface freezing monolayer in the ambient temperature range could have a significant importance when it is applied to practical applications.