Computational analysis of water dynamics in AOT reverse micelles
Computational analysis of water dynamics in AOT reverse micelles
复制标题
AOT 反胶束中水动力学的计算分析
DOI：
10.1016/j.molliq.2023.121340
复制
发表时间：
2023
影响因子：
6
通讯作者：
Sharma, Arun K.
中科院分区：
文献类型：
--
作者：
Crowder, Max;Tahiry, Frozan;Lizarraga, Isabel;Rodriguez, Stephanie;Peña, Nathaly;Sharma, Arun K.
可以在实验室和计算模拟中使用反胶束对气溶胶进行建模以进行详细的研究。在这些条件下描述承压水的一个长期存在的问题是岩心-界面的两态模型或岩心-中间界面的三态模型。在这项工作中，我们介绍了从完全原子化分子动力学模拟反胶束内水动力学的分析结果。反胶束的大小和组成通过w0表示，w0是水分子数与表面活性剂分子数之比。用双(2-乙基己基)琥珀酸磺酸钠(AOT)表面活性剂构建了w0为5~20的不同大小的反胶束，并在异辛烷溶剂中进行了模拟。在模拟中，随着反胶束尺寸的增加，停留时间和扩散系数都表现出越来越像散装水的行为。在10-20微秒的短时间范围内，旋转各向异性自相关用指数函数来模拟，而长时间数据用幂函数来模拟。同样，水在反胶束中的扩散也符合幂定律拟合。所有这些指标都表明，随着反胶束尺寸的增加，明显地朝着散装水的行为发展。此外，我们的结果还支持核-中间界面反胶束中水的三层模型。这些结果扩展了对反胶束中水动力学的理解，并为三层模型提供了进一步的证据。
Aerosols can be modeled for detailed investigations using reverse micelles in the laboratory as well as in computational simulations. A long-standing question in the description of confined water under these conditions is that of a two-state model of core – interface or a three-state model of core – intermediate – interface. In this work, we present results of analysis of water dynamics inside reverse micelles from fully atomistic molecular dynamics simulations. The size and composition of reverse micelles is expressed through w0, the ratio of the number of water molecules to the number of surfactant molecules. Reverse micelles of diverse sizes, with w0ranging from 5 to 20, were constructed with Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) surfactant and simulated within isooctane solvent. Residence time and diffusion coefficients, in the simulations, both behaved increasingly like bulk water with the increase in size of reverse micelles. Rotational anisotropy autocorrelation was modeled using exponential functions in the short time range of 10–20 ps and longer time data were modeled as a power law fit. Similarly, the diffusion of water in the reverse micelles was also modeled on a power law fit. All these metrics demonstrate a clear progression towards bulk water behavior as the reverse micelle size increases. Additionally, our results also support a 3-layer model of water in a reverse micelle of core – intermediate – interface. These results extend the understanding of water dynamics in reverse micelles and provide further evidence for the 3-layer model.