Constructing the phase diagram of sodium laurylethoxysulfate using dissipative particle dynamics.
Constructing the phase diagram of sodium laurylethoxysulfate using dissipative particle dynamics.
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DOI：
10.1016/j.jcis.2019.08.091
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发表时间：
2019-12
影响因子：
9.9
通讯作者：
Maria Panoukidou;C. Wand;A. Del Regno;Richard L. Anderson;P. Carbone
中科院分区：
文献类型：
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作者：
Maria Panoukidou;C. Wand;A. Del Regno;Richard L. Anderson;P. Carbone
十二烷基乙氧基硫酸钠（SLES）是一种重要的表面活性剂产品，它的各种中间相的映射是预测液体粘度的关键。在这里，我们想表明，使用适当的参数化粗粒度的分子模型可以提供结构信息的表面活性剂的解决方案，不容易实现通过experimental characterization.ExperimentsWe使用一套新的耗散粒子动力学参数专门开发的表面活性剂分子构建纯SLES在氯化钠的第一个相图。水溶液。FindingsWe发现，我们的DPD模型是能够重现这些类型的离子表面活性剂的预期形态的范围内，并与最近的流变数据和理论预测的基础上的包装参数的协议。我们计算了各种盐浓度的结构因子，并表明，从球形到蠕虫状胶束的变化也可以推断在中间q值的强度，其强度随着盐作为盐浓度的增加而降低的峰强度。通过改变羟乙基的含量，我们观察到羟乙基的加入增加了胶束的半径，并影响了胶束的形状和多分散性。最后，蠕虫状胶束的轮廓长度在中间盐浓度下观察到的基础上，提出了一个封闭的数学公式，能够预测的平均胶束轮廓长度给定的盐和表面活性剂的浓度。
HypothesisSodium Laurylethoxysulfate (SLES) is a fundamental ingredient in a wide range of surfactant products and the mapping of its various mesophases is pivotal in predicting the liquid viscosity. Here we want to show that the use of properly parameterised coarse-grained molecular models can provide structural information of the surfactant solutions not easily achievable through experimental characterization.ExperimentsWe use a novel set of Dissipative Particle Dynamics parameters specifically developed for surfactant molecules to construct the first phase diagram of pure SLES in sodium chloride/water solutions.FindingsWe found that our DPD model is able to reproduce the range of morphologies expected for these types of ionic surfactants and in agreement with recent rheological data and theoretical predictions based on the packing parameter. We calculated the structure factor for various salt concentrations and show that the change from spherical to worm-like micelles can be inferred also looking at the intensity of the peak at intermediateq-values which decreases in intensity as salt concentrations increase. Varying the ethoxyl groups we observe that the additional ethoxyl group increased the micellar radius and affected the micelles’ shape polydispersity in the system. Finally, based on the contour length of worm-like micelles observed at intermediate salt concentrations, a closed mathematical formula is proposed capable of predicting the average micellar contour length given the salt and surfactant concentrations.