Molecular Dynamics Simulation of Aerosol-OT Reverse Micelles
Molecular Dynamics Simulation of Aerosol-OT Reverse Micelles
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DOI：
10.1021/jp906915q
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发表时间：
2009-11-12
影响因子：
3.3
通讯作者：
Ladanyi, Branka M.
中科院分区：
文献类型：
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作者：
Chowdhary, Janamejaya;Ladanyi, Branka M.
对表面活性剂Aerosol-OT（AOT，琥珀酸二（2-乙基己基）酯磺酸钠）在异辛烷中形成的反胶束进行了分子动力学模拟。确定了适当的模拟方法，并将其应用于研究RM尺寸对反胶束结构的影响，如通过w（0）= [H2O]/[AOT]量化的。得到了分子的径向密度和本征密度分布、第一溶剂化层的电子对密度和电子对取向以及水-水氢键分布。这些不同的结构特征的基础上，我们发现，在表面活性剂界面的钠离子，磺酸盐头基，和水氧原子的组织是一致的伪晶格结构的w（0）= 2。RM尺寸的增加导致这种晶格的破坏，更多的钠离子从磺酸盐头基解离，并且这两种物质的水溶剂化都增加。水分子主要存在于RM的内部，并且仅在w（0）类似于7.5时表现出块状性质。一些水分子和钠离子存在于磺酸根间的头基区域，并与AOT羰基相互作用。
Molecular dynamics simulations are performed for the reverse micelles (RMs) formed by the surfactant Aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulfosuccinate) in isooctane. The appropriate simulation methodology is identified and applied to the study of the effect of RM size, as quantified by w(0) = [H2O]/[AOT], on the structure of the reverse micelle. The radial and intrinsic density profiles, pair densities and pair orientations in the first solvation shell, and water-water hydrogen bonding profiles were constructed. On the basis of these various structural characteristics, we find that the organization of sodium ions, sulfonate headgroup, and water oxygen atoms at the surfactant interface is consistent with a pseudolattice structure for w(0) = 2. An increase in the RM size leads to the disruption of this lattice, with more sodium ions dissociating from the sulfonate headgroup and ail increase in the aqueous solvation of these two species. The water molecules exist primarily in the interior of the RM and exhibit bulklike properties only for w(0) similar to 7.5. Some water molecules and sodium ions exist in the intersulfonate headgroup region and interact with the AOT carbonyl group.