Self-assembly of mixed dodecylamine-dodecanol molecules at the air/water interface based on large-scale molecular dynamics
Self-assembly of mixed dodecylamine-dodecanol molecules at the air/water interface based on large-scale molecular dynamics
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基于大规模分子动力学的混合十二胺-十二醇分子在空气/水界面的自组装
DOI：
10.1016/j.molliq.2018.12.076
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发表时间：
2019
影响因子：
6
通讯作者：
Sun Wei
中科院分区：
文献类型：
--
作者：
Wang Li;Sun Ning;Wang Zhen;Han Haisheng;Yang Yue;Liu Runqing;Hu Yuehua;Tang Honghu;Sun Wei
与纯DDA相比，十二烷基胺-酒精混合物在工业生产中具有优越的性能，近年来引起了人们的极大兴趣。表面活性剂在空气/水界面的自组装对其表面性能起着重要作用。然而，混合dda -醇在原子水平上的自组装仍然是未知的。本研究对不同配比的dda -十二醇（DOD）混合物进行了大规模的原子动力学模拟，以阐明其分子排列并解释协同效应。详细表征了DDA-DOD混合物的分子聚集、取向、角度分布和氢键分布等结构特性。模拟结果表明，不同比例的DDA-DOD混合分子的行为存在较大差异。由于头基之间的静电斥力很强，纯DDA分子的自组装不显著。纯DOD分子的表面活性不强，这是由于它们与水的氢键较少，水溶性较差。对于混合DDA - DOD， DOD的加入不直接影响DDA分子的排列；相反，由于表面活性剂链之间的范德华相互作用，DOD分子插入DDA分子之间，并在空气/水界面形成稳定的团簇。DDA和DOD之间存在两种主要的相互作用模式，包括表面活性剂链之间的范德华相互作用和它们头基之间的氢键相互作用。DOD和DDA分别在簇的形成和溶剂作用中起重要作用。这两种表面活性剂的比例会影响上述两种性能。该研究为研究混合表面活性剂的自组装簇提供了良好的策略，并在原子水平上支持了实验理论。
Dodecylamine (DDA)–alcohol mixtures have motivated great interest recently due to their superior performance in industrial processes compared with pure DDA. Self-assembly of surfactants at the air/water interface plays an important role in their surface properties. However, the self-assembly of mixed DDA–alcohol at an atomic level is still unknown. In this study, large-scale atomistic dynamic simulations of DDA–dodecanol (DOD) mixtures with different ratios were performed to clarify their molecular arrangement and explain the synergistic effect. The structural properties, such as molecular aggregation, orientation, angle distributions, and H bond distributions, of DDA–DOD mixtures were characterized in detail. Simulation results show considerable differences in the behavior of mixed DDA–DOD molecules with different ratios. The self-assembly of pure DDA molecules is not significant due to the strong electrostatic repulsion between head groups. The surface activity of pure DOD molecules is not strong due to their poor water solubility based on their fewer amounts of H-bonds with water. For mixed DDA–DOD, the addition of DOD does not directly affect the arrangement of DDA molecules; rather, DOD molecules insert between DDA molecules and form stable clusters at the air/water interface due to the van der Waals interactions between surfactant chains. Two main interaction patterns exist between DDA and DOD, including van der Waals interactions between the surfactant chains and H bonds between their head groups. DOD and DDA play an important role in forming the cluster and solvent action, respectively. The ratio of these two surfactants can affect the two above properties. This study provides a good strategy to investigate the self-assembly cluster of mixed surfactants and supports the experimental theory at the atomic level.