VISCOELASTIC MICELLAR SOLUTIONS - MICROSCOPY AND RHEOLOGY
VISCOELASTIC MICELLAR SOLUTIONS - MICROSCOPY AND RHEOLOGY
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DOI：
10.1021/j100180a086
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发表时间：
1992-01-09
影响因子：
--
通讯作者：
MILLER, WG
中科院分区：
文献类型：
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作者：
CLAUSEN, TM;VINSON, PK;MILLER, WG
以水杨酸盐（来自鼻）为结合反离子的十六烷基三甲基氯化铵（CTAC）水溶液的无伪影电子显微图和流变性能是反离子浓度的函数。在低[Sal-]时，CTAC溶液形成球状（球形）胶束（直径5nm），表现为牛顿流体。随着[Sal-]的增加，这些溶液形成线状或虫状胶束（直径5纳米，长度长达几微米），具有粘弹性和纠缠性。在中等[Sal-]下，这些溶液具有与半稀聚合物溶液相似的弛豫时间谱。在高[Sal-]时，单一的松弛时间占主导地位。粘弹性溶液的黏度表现出剪切减薄和幂律特性。作为[Sal-]的函数，零剪切粘度（eta(0)）最大比不含水杨酸盐溶液的初始粘度大5个数量级。随着[Sal-]的进一步增大，零剪切粘度随之降低3个数量级。丝状胶束形成后，流变性能随[Sal-]的变化而变化，而电子显微图均显示出相似的缠结丝状胶束图像。其中一些图像有少量封闭的环状丝状结构，表明环状胶束的存在。电镜样品在松弛前后进行热固定。在某些情况下，弛豫前的样品成像显示，由于样品制备过程中引起的剪切，线状胶束处于有序状态。
Artifact-free electron micrographs and rheological properties of aqueous solutions of cetyltrimethylammonium chloride (CTAC), with salicylate (from NaSal) as the binding counterion, are presented as a function of counterion concentration. At low [Sal-], CTAC solutions form globular (spherical) micelles (5 nm in diameter) and behave as Newtonian fluids. With increasing [Sal-], these solutions form threadlike or wormlike micelles (5 nm in diameter with lengths as long as several micrometers) that are viscoelastic and entangled. At moderate [Sal-], these solutions have a spectrum of relaxation times similar to semidilute polymer solutions. At high [Sal-], a single relaxation time dominates. The viscosity of the viscoelastic solutions shows shear thinning and power law behavior. As a function of [Sal-], the zero-shear viscosity (eta(0)) reaches a maximum 5 orders of magnitude greater than the initial viscosity of the solution with no salicylate. With further increase in [Sal-], the zero-shear viscosity then decreases 3 orders of magnitude. After the formation of threadlike micelles, the rheological properties change as a function of [Sal-], whereas the electron micrographs all show similar images of entangled threadlike micelles. Some of the images have a small number of closed circular threadlike structures, indicating the existence of ringlike micelles. Samples for electron microscopy were thermally fixed before and after relaxation. In some cases, the samples imaged before relaxation revealed the threadlike micelles in an ordered state due to the shear induced during sample preparation.