Structural rearrangements in self-assembled surfactant layers at surfaces.
The transition from compact to extended configuration in ionic surfactant layers under the influence of salt, surfactant surface density, and temperature is studied using the classical density functional theory (cDFT). The increase in ionic strength of an aqueous salt solution or in the surfactant surface density leads to the transition from the hemicylindrical to the perpendicular monolayer configuration of the molecules. Although producing the same structural rearrangement in the surfactant layer, the origin of the effect of salt and surface density is different. While the addition of salt increases the out-of-plane attractive interactions with the solvent, the increase in density results in the increase in the in-plane repulsion in the surfactant layer. The temperature effects are subtler and are mainly manifested in the reduction of the solution structuring at elevated temperatures.
Sushko
Maria L
ML
Pacific Northwest National Laboratory, Richland, Washington 99352, USA. maria.sushko@pnl.gov
Liu
Jun
J