Electrolyte-induced structural evolution of Triton X-100 micelles
Electrolyte-induced structural evolution of Triton X-100 micelles
复制标题
DOI：
10.1021/jp994424v
复制
发表时间：
2000-08-31
影响因子：
3.3
通讯作者：
Doherty, AP
中科院分区：
文献类型：
--
作者：
Charlton, ID;Doherty, AP
采用旋转圆盘电极伏安法，以二茂铁为电活性探针，测定了Triton X-100胶束的长时间自扩散系数随表面活性剂和电解质浓度的变化关系。胶束扩散符合线性相互作用理论，并产生胶束流体动力学半径值和相互作用参数作为电解质浓度的函数。在0.01-0.8 mol dm（-3）KCl的电解质浓度范围内，相互作用参数在3.4 - 3.6之间变化，这与排除的体积相互作用一致，表明加入电解质后胶束形状没有明显变化。胶束流体动力学半径相对于[KCl]线性变化，从4.22到6.21 nm，表明由于增加聚集数和“水合”的扁圆形胶束的渐进进化生长。半大调与半小调的轴比（a/B）从2.0增加到3.5，表明演化为更不对称的结构。胶束的分子量从77 700增加到326 000以上的电解质浓度范围内的研究，这主要是由于在自组装结构的外围水截留。发现特性粘度从6.09 cm（3）g（-1）降低到4.61 cm（3）g（-1），表明比胶束体积降低，这可能归因于脱水导致的环氧乙烷链塌陷。发现胶束比容的降低与电解质引起的浊点降低精确相关。
The long-time self-diffusion coefficients of Triton X-100 micelles have been determined as a function of surfactant and electrolyte concentrations using rotating disk electrode voltammetry in conjunction with ferrocene acting as an electroactive probe. Micellar diffusion conforms to the linear interaction theory and yields micellar hydrodynamic radii values and interaction parameters as a function of electrolyte concentration. The interaction parameters varied from 3.4 to 3.6 over the electrolyte concentration range 0.01-0.8 mol dm(-3) KCl, which is consistent with excluded volume interactions and indicated the absence of significant micellar shape changes with the addition of electrolyte. Micellar hydrodynamic radii varied linearly with respect to [KCI] from 4.22 to 6.21 nm, indicating the progressive evolutionary growth of the oblate micelles due to increasing aggregation number and "hydration". The semimajor to semiminor axial ratio (a/b) increased from 2.0 to 3.5, indicating evolution to a more asymmetric structure. Micellar molecular weights increased from 77 700 to 326 000 over the electrolyte concentration range studied, which is predominantly due to water entrapment at the periphery of the self-assembled structures. Intrinsic viscosities were found to decrease from 6.09 to 4.61 cm(3) g(-1), indicating a decrease in specific micellar volume, which may be attributed to ethylene oxide chain collapse due to dehydration. The decrease in micellar specific volume was found to correlate precisely with the electrolyte induced decrease of the cloud point.