羟基取代双烷烃链苯磺酸盐水气界面单层膜的分子动力学模拟

采用分子动力学模拟方法考察2-羟基-3,5-烷基苯磺酸钠表面活性剂分子在水气界面形成单层膜的过程,通过体系各组分的密度分布分析单层膜的形态,采用径向分布函数和氢键分布考察含有羟基的极性基在界面处的吸附构型,并根据转动时间相关函数对双疏水链的吸附构型进行分析。结果表明:羟基的存在减弱了极性基之间的静电排斥作用,增加了分子的饱和吸附量;两条烷烃链具有不同的界面吸附构型,烷烃链间的叠加缠绕增强了溶剂对表面活性剂分子的疏水力作用。

Molecular dynamics simulation of hydroxyl substituting dialkyl benzene sulfonate self-assembly membrane at air-water interface

The forming process of self-assembly membrane(SAM) consisting of sodium 2-hydroxy-3,5-alkyl benzene sulfonate surfactant molecules at air-water interface was studied by molecular dynamics simulation.The morphology of monolayer was analyzed through density profiles,and the configuration of head groups was investigated by analysis of radial distribution function(RDF) and H-bonding distribution.And the configuration of hydrophobic alkyl chains was also investigated preliminarily by rotational time correlation function.The results show that the hydroxyl weakens electrostatic interaction among head groups and increases the surface excess concentration.Moreover,the two alkyl chains take remarkably different configuration,and the tendency to entanglement of these chains in the SAM may enhance the hydrophobic interaction between solvent and surfactant molecules.