Sharma Suraj Chandra, Shrestha Rekha Goswami, Shrestha Lok Kumar, Aramaki Kenji
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
J Phys Chem B. 2009 Feb 12;113(6):1615-22. doi: 10.1021/jp808390c.
Formation and rheological behavior of viscoelastic wormlike micelles in an aqueous solution of a mixed system of nonionic fluorocarbon surfactants, perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)nH (abbreviated as C8F17EOn, n=20 and 3), was studied. A partial ternary phase diagram of water/C8F17EO20/C8F17EO3 was constructed at 25 degrees C by visual inspection through crossed polarizers. In the water/surfactant binary system, C8F17EO20 forms an isotropic micellar solution over a wide concentration range (approximately 80 wt %). The micellar solution of the C8F17EO20 can solubilize a significant amount of C8F17EO3, and the solubility increases with increasing C8F17EO20 concentration. With successive addition of C8F17EO3 to the aqueous C8F17EO20 solution, viscosity increases rapidly, and a viscoelastic solution is formed. The viscosity of the viscous sample was approximately 5th order of magnitude of pure water. The viscoelastic solution follows the Maxwell model typical of wormlike micelles at low-frequency region. With further addition of C8F17EO3 the viscosity decreases, and phase separation occurs. Addition of perfluoropolyether oil, (C3F6O)nCOOH, to the viscoelastic solution decreases the viscosity monotonically until phase separation. On the other hand, when perfluorodecalin oil, C10F18, is added, viscosity first decreases and attains a limiting value before excess oil phase separates out. The viscosity decrease in water/surfactant/oil systems is possibly caused by the microstructural transition in the network structure. Small-angle X-ray scattering (SAXS) measurements were performed to complement the rheological data. It has been found that the C8F17EO3 induces one-dimensional growth to the C8F17EO20 micelles. On the other hand, when (C3F6O)nCOOH is added, wormlike-sphere type transition is more likely to occur.
研究了在非离子型碳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，n = 20和3）的混合体系水溶液中粘弹性蠕虫状胶束的形成及流变行为。通过在25℃下透过交叉偏振器的目视检查构建了水/C8F17EO20/C8F17EO3的部分三元相图。在水/表面活性剂二元体系中，C8F17EO20在很宽的浓度范围（约80 wt%）内形成各向同性的胶束溶液。C8F17EO20的胶束溶液能够溶解大量的C8F17EO3，且溶解度随C8F17EO20浓度的增加而增大。随着向C8F17EO20水溶液中连续添加C8F17EO3，粘度迅速增加，并形成粘弹性溶液。粘性样品的粘度约为纯水的5个数量级。该粘弹性溶液在低频区域遵循典型的蠕虫状胶束的麦克斯韦模型。随着进一步添加C8F17EO3，粘度降低，并发生相分离。向粘弹性溶液中添加全氟聚醚油(C3F6O)nCOOH会使粘度单调降低直至相分离。另一方面，当添加全氟萘烷油C10F18时，粘度先降低并达到一个极限值，然后才会有过量的油相分离出来。水/表面活性剂/油体系中的粘度降低可能是由网络结构中的微观结构转变引起的。进行了小角X射线散射（SAXS）测量以补充流变学数据。已发现C8F17EO3会诱导C8F17EO20胶束进行一维生长。另一方面，当添加(C3F6O)nCOOH时，更有可能发生蠕虫状球体类型的转变。
