Cheong Daniel W, Panagiotopoulos Athanassios Z
Department of Chemical Engineering, Princeton University, Princeton, New Jersey 08544, USA.
Langmuir. 2006 Apr 25;22(9):4076-83. doi: 10.1021/la053511d.
A lattice model for ionic surfactants with explicit counterions is proposed for which the micellization behavior can be accurately determined from grand canonical Monte Carlo simulations. The model is characterized by a few parameters that can be adjusted to represent various linear surfactants with ionic headgroups. The model parameters have a clear physical interpretation and can be obtained from experimental data unrelated to micellization, namely, geometric information and solubilities of tail segments. As a specific example, parameter values for sodium dodecyl sulfate were obtained by optimizing for the solubility of hydrocarbons in water and the structural properties of dodecane. The critical micelle concentration (cmc), average aggregation number, degree of counterion binding, and their dependence on temperature were determined from histogram reweighting grand canonical Monte Carlo simulations and were compared to experimental results. The model gives the correct trend and order of magnitude for all quantities but underpredicts the cmc and aggregation number. We suggest ways to modify the model that may improve agreement with experimental values.
提出了一种带有显式抗衡离子的离子表面活性剂晶格模型，通过巨正则蒙特卡罗模拟可以准确确定其胶束化行为。该模型由几个参数表征，这些参数可进行调整以代表具有离子头基的各种线性表面活性剂。模型参数具有明确的物理解释，并且可以从与胶束化无关的实验数据中获得，即尾段的几何信息和溶解度。作为一个具体例子，通过优化烃类在水中的溶解度和十二烷的结构性质，获得了十二烷基硫酸钠的参数值。通过直方图重加权巨正则蒙特卡罗模拟确定了临界胶束浓度（cmc）、平均聚集数、抗衡离子结合度及其对温度的依赖性，并与实验结果进行了比较。该模型给出了所有量的正确趋势和量级，但对临界胶束浓度和聚集数的预测偏低。我们提出了修改该模型的方法，可能会改善与实验值的一致性。
