Mechanism of the Mixed Surfactant Micelle Formation
Mechanism of the Mixed Surfactant Micelle Formation
复制标题
混合表面活性剂胶束形成机制
DOI：
10.1021/jp101032z
复制
发表时间：
2010-06-17
影响因子：
3.3
通讯作者：
Du, Youru
中科院分区：
文献类型：
--
作者：
Cui, Xiaohong;Jiang, Yan;Du, Youru
本文从分子水平上对混合胶束的形成过程进行了全面的描述。采用H-1核磁共振谱研究了二元表面活性剂水溶液体系、离子/非离子混合体系（12-2-12/TX-100、14-2-14/TX-100和SDS/TX-100）以及离子/离子混合体系（12-2-12/TTAB、14-2-14/TTAB和SDS/CTAB）在重水溶液中形成混合胶束的机理。通过分析化学位移和共振峰强度的变化，得到了混合表面活性剂溶液中各组分的临界胶束化浓度。化学位移的变化表明，在12-2-12/TX-100和SDS/TX-100体系中，TX-100先形成胶束，然后12-2-12和SDS分子分别融合在胶束中，这一点已被二维NOESY实验所证实。相比之下，14-2-14是14-2-14/TX-100体系中第一个形成胶束的组分。虽然12-2-12和14-2-14是类似物，并且仅在疏水链的长度上相差两个亚甲基，但它们在与TX-100的混合物中的胶束化过程中表现出不同的行为。实验结果表明，在二元表面活性剂体系中，随着混合溶液总浓度的增加，混合溶液中cmc较低的组分首先聚集，然后另一组分融合，形成混合胶束。对于离子/离子溶液、12-2-12/TTAB、14-2-14/TTAB和SDS/CTAB获得了相同的结果。上述结果表明，两种混合表面活性剂不同步聚集。这显然表明，所谓的“混合表面活性剂溶液的临界胶束浓度”需要重新考虑。
This article provides a full description of the mixed micelle formation process at a molecular level. The mechanism of mixed micelle formation in binary surfactant aqueous solution systems, ionic/nonionic mixed systems (12-2-12/TX-100, 14-2-14/TX-100, and SDS/TX-100), and ionic/ionic mixed systems (12-2-12/TTAB, 14-2-14/TTAB, and SDS/CTAB), in heavy water solutions was studied by H-1 NMR spectroscopy. The critical micellization concentrations of each individual component in the mixed surfactant solutions were gained by analyzing changes in chemical shift and intensities of resonance peaks. The chemical shift changes indicated that in the 12-2-12/TX-100 and SDS/TX-100 systems, micelles of TX-100 formed first, and then 12-2-12 or SDS molecules were fused in the micelles, respectively, which has been proved by 2D NOESY experiments. In contrast, 14-2-14 was the first component to form the micelles in the 14-2-14/TX-100 system. Although 12-2-12 and 14-2-14 are analogs and differ only in the length of the hydrophobic chain by two methylene groups, they showed different behaviors in the micellization processes in the mixture with TX-100. The observation suggests that in the binary surfactant system under current study, the component with lower cmc in the mixed solution aggregates first; then, the other one fuses, resulting in the mixed micelles as the total concentration increases. The same results were obtained for the ionic/ionic solutions, 12-2-12/TTAB, 14-2-14/TTAB, and SDS/CTAB. The above results suggest that the two mixed surfactants do not aggregate synchronously. It obviously demonstrates that the so-called "cmc of the mixed surfactant solution" needs reconsideration.