Quantitative effect of nonionic surfactant partitioning on the hydrophile-lipophile balance temperature.
Quantitative effect of nonionic surfactant partitioning on the hydrophile-lipophile balance temperature.
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DOI：
10.1021/la030306u
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发表时间：
2004-03
期刊：
影响因子：
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通讯作者：
M. Ben Ghoulam;N. Moatadid;A. Graciaa;J. Lachaise
中科院分区：
文献类型：
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作者：
M. Ben Ghoulam;N. Moatadid;A. Graciaa;J. Lachaise
实验测定了水/非离子表面活性剂/异辛烷体系在温度-表面活性剂总浓度图上的相行为。表面活性剂为单分布聚氧乙烯乙二醇正十二烷基醚。它们被用作两种、三种或五种化合物的模型混合物，或用作商业表面活性剂的组分。结果表明，随着表面活性剂浓度的降低，体系的相图逐渐向最高温度方向弯曲。每个相图的特征在于HLB（亲脂平衡）温度与全球表面活性剂浓度的曲线。对于任何固定的全局表面活性剂浓度，该温度是三相区域的中间温度;它可以由表面活性剂的HLB温度的加性规则计算，该加性规则由表面活性剂在水/油界面处的摩尔分数加权。这些摩尔分数通过使用表面活性剂分配的假相模型来确定。计算需要了解临界胶束浓度、水和油之间的分配系数以及混合物中每种表面活性剂的HLB温度。这种处理可以用来正确地预测HLB温度的变化的表面活性剂的混合物研究与全球表面活性剂浓度。此外，这些计算表明，在最低的全球浓度下观察到的相图的曲率是由于最有利的分配朝向最低乙氧基化表面活性剂分子的油。
Phase behaviors of water/nonionic surfactants/isooctane systems are determined experimentally in temperature-global surfactant concentration diagrams. The surfactants are monodistributed polyoxyethylene glycol n-dodecyl ether. They are used as model mixtures of two, three, or five compounds or as constituents of a commercial surfactant. It is found that the phase diagrams of these systems are bent gradually toward the highest temperatures as the global surfactant concentration decreases. Each phase diagram is well-characterized by the curve of the HLB (hydrophile-lipophile balance) temperature versus the global surfactant concentration. For any fixed global surfactant concentration, this temperature is the middle temperature of the three-phase region; it can be calculated from an additive rule of the HLB temperatures of the surfactants weighted by their mole fractions at the water/oil interface. These mole fractions are determined through the pseudophase model using surfactant partitioning. Calculations require the knowledge of the critical micelle concentration, the partition coefficient between water and oil, and the HLB temperature of each surfactant of the mixture. This treatment can be used to correctly predict the variation of the HLB temperatures of the surfactant mixtures studied versus the global surfactant concentration. Furthermore, these calculations show that the observed curvature of the phase diagrams at the lowest global concentrations is due to the most favorable partitioning toward the oil of the lowest ethoxylated surfactant molecules.