Sharma Suraj Chandra, Acharya Durga P, Aramaki Kenji
Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
Langmuir. 2007 May 8;23(10):5324-30. doi: 10.1021/la0700523. Epub 2007 Apr 17.
Formation and rheological behavior of viscoelastic wormlike micelles in aqueous solution of a mixed system of nonionic fluorinated surfactants, perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)nH (abbreviated as C8F17EOn) was studied. In the water-surfactant binary system C8F17EO20 forms an isotropic micellar solution over wide concentration range (>85 wt %) at 25 degrees C. With successive addition of C8F17EO1 to the aqueous C8F17EO20 solution, viscosity of the solution increases swiftly, and a viscoelastic solution is formed. The oscillatory rheological behavior of the viscoelastic solution can be described by Maxwell model at low-frequency region, which is typical of wormlike micelles. With further addition of C8F17EO1, the viscosity decreases after a maximum and phase separation occurs. Addition of a small amount of fluorinated oils to the wormlike micellar solution disrupts the network structure and decreases the viscosity sharply. It is found that polymeric oil, PFP (F-(C3F6O)nCF2CF2COOH), decreases the viscosity more effectively than the perfluorodecalin (PFD). The difference in the effect of oil on rheological properties is explained in terms of the solubilization site of the oils in the hydrophobic interior of the cylindrical aggregates, and their ability to induce rod-sphere transition.
研究了非离子型含氟表面活性剂全氟烷基磺酰胺乙氧基化物C8F17SO2N(C3H7)(CH2CH2O)nH（简称为C8F17EOn）混合体系水溶液中粘弹性蠕虫状胶束的形成及流变行为。在水-表面活性剂二元体系中，C8F17EO20在25℃下较宽的浓度范围（>85 wt%）内形成各向同性胶束溶液。向C8F17EO20水溶液中连续加入C8F17EO1时，溶液粘度迅速增加，并形成粘弹性溶液。该粘弹性溶液的振荡流变行为在低频区域可用麦克斯韦模型描述，这是蠕虫状胶束的典型特征。进一步加入C8F17EO1后，粘度在达到最大值后降低，并发生相分离。向蠕虫状胶束溶液中加入少量含氟油会破坏网络结构并使粘度急剧降低。发现聚合油PFP（F-(C3F6O)nCF2CF2COOH）比全氟萘烷（PFD）更有效地降低粘度。从油在圆柱形聚集体疏水内部的增溶位点及其诱导棒-球转变的能力方面解释了油对流变性质影响的差异。
