A many-body dissipative particle dynamics parametrisation scheme to study behaviour at air-water interfaces.
A many-body dissipative particle dynamics parametrisation scheme to study behaviour at air-water interfaces.
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DOI：
10.1039/d3sm00276d
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发表时间：
2023-05
期刊：
影响因子：
3.4
通讯作者：
Rachel L Hendrikse;C. Amador;M. Wilson
中科院分区：
文献类型：
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作者：
Rachel L Hendrikse;C. Amador;M. Wilson
本文提出了多体耗散粒子动力学(MDPD)的一种通用参数化方案。该方案基于将模型组分与实验表面张力和化学势进行匹配。这使我们能够获得复杂、多组分体系的正确表面和混合行为。通过模拟非离子聚氧乙烯烷基醚表面活性剂在空气/水界面的行为来检验该方法。特别考察了表面活性剂头部基团中环氧乙烷单元数的影响。我们发现与许多实验获得的参数很好地一致，例如每个分子的最小表面积；随着表面活性剂表面密度的增加，表面张力降低。此外，我们观察到了一个定向转变，从低表面覆盖率时直接位于水面上的表面活性剂，到高表面覆盖率时相对于表面法线平行或倾斜的表面活性剂。参数方案还扩展到包括两性离子表面活性剂十二烷基二甲胺氧化物(LDAO)，其中我们提供了很好的预测在最大表面覆盖下的表面张力。这里，如果我们超过这个范围，我们就能够演示表面活性剂层自发产生胶束的过程。
In this article, we present a general parametrisation scheme for many-body dissipative particle dynamics (MDPD). The scheme is based on matching model components to experimental surface tensions and chemical potentials. This allows us to obtain the correct surface and mixing behaviours of complex, multicomponent systems. The methodology is tested by modelling the behaviour of nonionic polyoxyethylene alkyl ether surfactants at an air/water interface. In particular, the influence of the number of ethylene oxide units in the surfactant head group is investigated. We find good agreement with many experimentally obtained parameters, such as minimum surface area per molecule; and a decrease in the surface tension with increasing surfactant surface density. Moreover, we observe an orientational transition, from surfactants lying directly on the water surface at low surface coverage, to surfactants lying parallel or tilted with respect to the surface normal at high surface coverage. The parametrisation scheme is also extended to cover the zwitterionic surfactant lauryldimethylamine oxide (LDAO), where we provide good predictions for the surface tension at maximum surface coverage. Here, if we exceed this coverage, we are able to demonstrate the spontaneous production of micelles from the surface surfactant layer.