烷基甜菜碱类两性离子型表面活性剂胶束化行为的分子模拟研究

Molecular simulation study on the micellization behavior of betaine-type zwitterionic surfactants

以两性离子型表面活性剂甜菜碱为研究对象,采用粗粒度分子动力学方法,构建不同结构的烷基甜菜碱模型,考察其联结基团和疏水尾链对溶液体系中自聚体的溶液行为的影响,分析了自聚体胶束的弯曲角分布、相对形状各异性以及径向分布函数等参数,探究了球形、棒状、分支状胶束的形状转变机制。研究结果表明,随着浓度的增加,在联结基团的作用下,两性离子型表面活性剂分子发生弯曲,小胶束交联融合形成棒状—分支状胶束转变;疏水尾链长度增加会导致胶束体积变化从而降低分子间相互作用,小胶束易融合形成球形—棒状胶束的形状转变。文章为相似体系下的理论探索提供了一种创新的思维角度,对两性离子型表面活性剂的研究和应用有一定的指导意义。

Betaine-type zwitterionic surfactants were used as the research objects.The technique of coarse-grained molecular dynamics was used to construct alkyl betaine models of different structures,and the effects of linking group and hydrophobic tail on the aggregation in the solution system were investigated.The bending angle distribution,relative shape anisotropy and radial distribution function of aggregates(micelles)were analyzed.The shape transformation mechanism of spherical,rod-shaped and branched micelles was explored.The research results show that,with the increase of concentration,under the action of the linking group,the zwitterionic surfactant molecules bend and the small micelles are cross-linked and fused to form a rod-branched micelle transition;the increase of the chain length of hydrophobic tail will cause the changes in0 nms icelle 2 v.2 o nlsu me thu3 s.5 tnos reduc4 e.0 tnhsMicellar fusion process e intermolecular interaction,and Lthe small micelles are easy to fuse to spacer=1,Nsurf=100 Lspacer=0,Nsurf=100 form a sphere-to-rod transition.This article provides an innovative thinking angle for theoretical exploration for similar systems,and it has certain guiding significance for the rMesiceelalarr cmhor pahnoldog y application of zwitterionic surfactants.