The characteristic curvature of ionic surfactants
The characteristic curvature of ionic surfactants
复制标题
DOI：
10.1007/s11743-008-1065-7
复制
发表时间：
2008-07-01
影响因子：
1.6
通讯作者：
Bhakta, Arti Sh.
中科院分区：
文献类型：
--
作者：
Acosta, Edgar J.;Yuan, Jessica Sh.;Bhakta, Arti Sh.
表征表面活性剂分子的亲水亲油性质一直是胶体科学家和技术人员的挑战。亲水亲油平衡（HLB）、填充因子、相转化温度（PIT）和表面活性剂的自然曲率都是试图解决这个问题的术语。在这篇文章中，我们建立在亲油-亲油差异概念（HLD）（Salager等人，Langmuir，16，5534-5539，2000）的基础上，开发了一种基于混合离子表面活性剂微乳液的相行为来确定离子表面活性剂的特征曲率（Cc）的方法。本质上，该方法包括评估最佳电解质浓度的变化作为测试表面活性剂与参考表面活性剂二己基磺基琥珀酸钠（SDHS）的混合物中的摩尔分数的函数，并应用离子表面活性剂混合物的适当HLD方程来确定Cc。Cc的值被确定为一系列的表面活性剂，包括十二烷基硫酸钠（SDS），十二烷基苯磺酸钠（SDBS），环烷酸钠，和其他。该方法也外推到非离子添加剂和亲水性连接剂。据观察，Cc的计算值与基团贡献模型预测的值相似，但是所提出的方法甚至可以用于复杂的表面活性剂混合物。最后，当将Cc值与表观填充因子和HLB值进行比较时，发现Cc与离子型表面活性剂的表观填充因子相关，并且Cc与非离子型两亲物的HLB值相关。讨论了Cc的物理解释及其在油-表面活性剂-水体系净平均曲率状态方程中的应用。
Characterizing the hydrophilic-lipophilic nature of a surfactant molecule has been a challenge for colloid scientists and technologists. The hydrophilic-lipophilic balance (HLB), the packing factor, the phase inversion temperature (PIT) and the natural curvature of the surfactant are all terms that seek to address this issue. In this article we build on the hydrophilic-lipophilic difference concept (HLD) (Salager et al. Langmuir, 16, 5534-5539, 2000) to develop a methodology to determine a characteristic curvature (Cc) for ionic surfactants based on the phase behavior of mixed ionic surfactant microemulsions. In essence, the method consists of evaluating the shift in optimal electrolyte concentration as a function of the mole fraction of the test surfactant in a mixture with a reference surfactant, sodium dihexyl sulfosuccinate (SDHS) and applying the appropriate HLD equation for ionic surfactant mixtures to determine Cc. The values of Cc were determined for a range of surfactants, including sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), sodium naphthenate, and others. The method was also extrapolated to nonionic additives and hydrophilic linkers. It was observed that the calculated values of Cc were similar to those predicted by group contribution models, however the proposed method can be used even for complex surfactant mixtures. Finally, when Cc values were compared to apparent packing factor and HLB values, it was found that Cc is correlated with the apparent packing factor of ionic surfactants, and that Cc correlates with the HLB value for nonionic amphiphiles. The physical interpretation of Cc, and its potential application in the Net-Average Curvature equation of state for oil-surfactant-water systems is discussed.