Azobenzene dye induced micelle to vesicle transition in cationic surfactant aqueous solutions.
Azobenzene dye induced micelle to vesicle transition in cationic surfactant aqueous solutions.
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DOI：
10.1016/j.jcis.2009.11.056
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发表时间：
2010-03
影响因子：
9.9
通讯作者：
Li Li-Li;Yi Yang;Jinfeng Dong;Xuefeng Li
中科院分区：
文献类型：
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作者：
Li Li-Li;Yi Yang;Jinfeng Dong;Xuefeng Li
采用光响应偶氮苯染料 4-[(E)-苯基二氮烯基]苯甲酸钠 (AZONa)，在水溶液中用十六烷基三甲基溴化铵 (CTAB) 诱导微观结构变化。通过采用浊度、粘度和动态光散射测量以及低温透射电子显微镜，研究了通过蠕虫状胶束的球形胶束到囊泡的转变。在 [AZONa]/[CTAB] 摩尔比为 0.65 时，零剪切粘度达到最大值，清楚地表明蠕虫状胶束的形成，该胶束在低剪切频率下遵循经典的麦克斯韦行为。在此临界摩尔比下，温度升高导致蠕虫状胶束的破裂，而当表面活性剂浓度在 10 至 40 mM 之间变化时，粘度 η0 显示出以缩放定律为特征的三个增长域。 η0 的快速增加可以通过溶液静电排斥的不完全屏蔽来解释。当浓度[CTAB]=20mM以上时，η0的降低是由于形成了分支蠕虫状胶束。
A photo-responsive azobenzene dye, sodium 4-[(E)-phenyldiazenyl] benzoate (AZONa), was employed to induce microstructural changes with cetyltrimethylammonium bromide (CTAB) in aqueous solution. A spherical micelle to vesicle transition via wormlike micelles was investigated by employing turbidity, viscosity, and dynamic light scattering measurements, as well as cryo-transmission electronic microscopy. At a certain molar ratio [AZONa]/[CTAB] of 0.65 the zero-shear viscosity achieve a maximum, showing clearly the formation of wormlike micelles that obey the classic Maxwellian behavior at low shear frequencies. At this critical molar ratio, an increase in temperature resulted in the breakdown of wormlike micelles, whereas the viscosity η0showed three domains of growth characterized by scaling laws as the surfactant concentration was varied between 10 and 40mM. The rapid increase in η0could be explained by an incomplete screening of electrostatic repulsions of the solution. The decrease in η0was due to the formation of branched wormlike micelles above once a concentration [CTAB]=20mM.