Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
J Colloid Interface Sci. 2010 May 15;345(2):293-301. doi: 10.1016/j.jcis.2010.02.062. Epub 2010 Mar 3.
Molecular dynamics simulations of mixtures of sodium dodecyl sulfate (SDS) and 1-dodecanol molecules on a graphite surface were carried out at low and high concentration to investigate the formation of aggregates on the solid plate. The simulations showed that at low concentration the surfactants were well adsorbed on the surface by forming layers structures or a hemicylinder aggregate for a slightly higher surfactant concentration whereas at the highest concentration the surfactants formed monolayer-like structures localized away from the graphite surface with a water bin between the monolayer and the graphite plate. Therefore, we obtained different arrays of those observed in recent simulations of pure SDS adsorbed on graphite at the same concentration reported in the literature. The unexpected water layer between the 1-dodecanol and the graphite surface, at the highest concentration, was explained in terms of the Hamaker constants. The present results suggest that the formation of aggregates on solid surfaces is a combined effect not only of the surfactant-surfactant and the surfactant-wall interactions but also of the surfactant concentration.
在低浓度和高浓度下，对十二烷基硫酸钠（SDS）和 1-十二醇分子在石墨表面上的混合物进行了分子动力学模拟，以研究固体板上聚集物的形成。模拟表明，在低浓度下，表面活性剂通过形成层状结构或半圆柱状聚集体来很好地被吸附在表面上，对于稍高的表面活性剂浓度，而在最高浓度下，表面活性剂形成单层状结构，远离石墨表面，在单层和石墨板之间存在水层。因此，我们获得了与文献中报道的在相同浓度下纯 SDS 吸附在石墨上的最近模拟中观察到的不同排列。在最高浓度下，在 1-十二醇和石墨表面之间出乎意料的水层，根据哈默常数得到了解释。本结果表明，固体表面上聚集物的形成不仅是表面活性剂-表面活性剂和表面活性剂-壁相互作用的综合效应，而且是表面活性剂浓度的综合效应。
