DYNAMICAL PROPERTIES OF SALT-FREE VISCOELASTIC MICELLAR SOLUTIONS
DYNAMICAL PROPERTIES OF SALT-FREE VISCOELASTIC MICELLAR SOLUTIONS
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DOI：
10.1021/la00018a018
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发表时间：
1994-06-01
期刊：
影响因子：
3.9
通讯作者：
CANDAU, SJ
中科院分区：
文献类型：
--
作者：
KERN, F;LEQUEUX, F;CANDAU, SJ
流变学实验进行了“二聚”的表面活性剂乙二基-α，ω-双（十二烷基二甲基溴化铵）作为表面活性剂的体积分数和温度的函数的胶束水溶液。目的是通过系统的线性粘弹性研究静电相互作用对胶束尺寸的影响。零剪切粘度的结果表明，急剧的交叉从一个稀的制度，其中胶束的增长是非常弱的制度的快速增长，与理论预测一致。然而，在进一步增加的体积分数，观察到的零剪切粘度的最大值，这表明胶束长度也经历了最大值。这是证实了最近开发的模型的基础上，考虑到爬行和劳斯过程的粘弹性光谱的分析。在高体积分数范围内观察到的胶束长度的减少已被解释为由于与理论预测的胶束电离度随体积分数的增加相关的有效端帽能量的减少。静电相互作用的影响也出现在表现出更大的体积分数依赖性比在高度筛选胶束的平台模量的行为。
Rheological experiments were carried out on aqueous micellar solutions of the ''dimeric'' surfactant ethanediyl-alpha,omega-bis(dodecyldimethylammonium bromide) as a function of surfactant volume fraction and temperature. The aim was to investigate the effect of electrostatic interactions on the micellar size through the linear viscoelastic properties of the system. The zero-shear viscosity results indicate a sharp crossover from a dilute regime in which the micelle growth is very weak to a regime of rapid growth, in agreement with the theoretical predictions. However, upon increasing further the volume fraction, a maximum of the zero-shear viscosity is observed which suggests that the micellar length also goes through a maximum. This is confirmed by the analysis of the viscoelastic spectra on the basis of the recently developed models taking into account both reptation and Rouse processes. The decrease of micellar length observed in the high volume fraction range has been interpreted as due to the decrease of the effective end-cap energy associated with the theoretically predicted increase of the micelle ionization degree with volume fraction. The effect of the electrostatic interactions also appears in the behavior of the plateau modulus that exhibits a larger volume fraction dependence than in highly screened micelles.