Department of Chemical and Biological Engineering and Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544, USA.
J Phys Chem B. 2012 Mar 1;116(8):2430-7. doi: 10.1021/jp209207p. Epub 2012 Feb 16.
Molecular dynamics simulations have been used to study the micellization behavior of atomistic models for sodium alkyl sulfates in explicit water. A major finding of the present work is the observation of a strong dependence of free surfactant concentration on overall surfactant concentration, that has not been reported previously and that is key to comparing simulation results for the critical micelle concentration (CMC) to experimental data. The CMC and aggregate size distributions were obtained for alkyl tail lengths from six to nine at temperatures from 268 to 363 K, from 400 ns simulations covering a number of surfactant and water model combinations. The free surfactant concentration is much lower than the critical micelle concentration for strongly micellizing systems at the relatively high concentrations accessible by simulations. Thus, counterion association must be accounted for in determining the CMC from the raw simulation data. Simulation results are in qualitative agreement with experimental trends for aggregate size and CMC as functions of alkyl tail length and temperature.
分子动力学模拟已被用于研究在明水环境中，针对钠烷基硫酸盐的原子模型的胶束化行为。本工作的一个主要发现是观察到自由表面活性剂浓度对总表面活性剂浓度的强烈依赖性，这在以前的报道中尚未观察到，并且是将临界胶束浓度（CMC）的模拟结果与实验数据进行比较的关键。CMC 和聚集物尺寸分布已针对从 6 到 9 的烷基尾长获得，温度范围从 268 到 363 K，使用 400 ns 的模拟覆盖了许多表面活性剂和水模型组合。在相对较高的模拟可达到的浓度下，对于强胶束化体系，自由表面活性剂浓度远低于临界胶束浓度。因此，必须在从原始模拟数据确定 CMC 时考虑抗衡离子缔合。模拟结果与实验结果在聚集物尺寸和 CMC 作为烷基尾长和温度的函数方面定性一致。
