Polymer Physics, Department of Materials, ETH Zürich, Zürich CH-8093, Switzerland.
Phys Chem Chem Phys. 2018 Jun 13;20(23):16238-16246. doi: 10.1039/c8cp01632a.
Computer simulations are a useful tool to explore the effects of interactions and structure of surfactants on interfacial microstructure and properties. Starting with "molecular-level", three-dimensional reference systems of short amphiphilic surfactants at fluid-fluid interfaces, we here derive effective interaction potentials for the corresponding two-dimensional systems of structureless particles confined to the interface plane. These reference systems are comprised of two immiscible mono atomic fluids (water- and oil-like particles) and nonionic linear amphiphilic surfactants. Our results show that coarse grained interaction potentials are only weakly dependent on surface concentration but their behavior is strongly dependent on surfactant interactions. The coarse grained system preserves the in-plane surfactant center-of-mass pair correlation function at the interface and the results of surface pressure-area isotherms are in a good agreement. This approach can be extended straightforwardly to other types of surfactants at both fluid-fluid and fluid-gas interfaces providing us with an effective pairwise interaction potential for the surfactant monolayer. These effective interactions can be used to explore large-scale self-assembly within the monolayer especially at low surface concentrations where reference simulations are extremely time-consuming.
计算机模拟是探索表面活性剂相互作用和结构对界面微观结构和性质影响的有用工具。从“分子水平”开始，我们针对短两亲性表面活性剂在流体-流体界面处的三维参考体系，推导出了相应的二维无结构粒子限制在界面平面内的系统的有效相互作用势。这些参考体系由两种不混溶的单原子流体（水相和油相粒子）和非离子线性两亲表面活性剂组成。我们的结果表明，粗粒相互作用势仅与表面浓度弱相关，但它们的行为强烈依赖于表面活性剂相互作用。粗粒体系在界面处保留了表面活性剂质心对关联函数，并且表面压-面积等温线的结果非常吻合。这种方法可以直接扩展到其他类型的表面活性剂在流体-流体和流体-气界面，为我们提供了表面活性剂单层的有效成对相互作用势。这些有效相互作用可用于探索单层内的大规模自组装，特别是在参考模拟极其耗时的低表面浓度下。
