Szymczyk Katarzyna, Jańczuk Bronisław
Department of Interfacial Phenomena, Faculty of Chemistry, Maria Curie-Skłodowska University, Maria Curie-Skłodowska Sq. 3, 20-031 Lublin, Poland.
Langmuir. 2009 Apr 21;25(8):4377-83. doi: 10.1021/la804183n.
The thermodynamics of micellization of mixed anionic/anionic surfactant solutions, that is, sodium dodecyl sulfate (SDDS) and sodium decyl sulfate (SDS), have been studied by surface tension, density, and conductivity measurements. The obtained results indicate that the values of critical micelle concentration strongly depend on the composition of the mixture and that the mole fraction of surfactants in the mixed micelle calculated on the basis of Rosen and Villeneuve approaches are different from those in the bulk phase. The small negative deviation from the linear relationship between the critical micelle concentrations and composition of SDDS and SDS mixtures in the bulk phase, the values of the molecular interaction parameters, activity coefficients, and the excess Gibbs energy of mixed micelle formation calculated on the basis of Rosen and Villeneuve approaches and calculations based on the MT theory of Blankschtein proved that there is synergism in mixed micelle formation of aqueous solutions of SDDS and SDS. It was also found that the values of the standard Gibbs energy of micellization for the mixture of these two surfactants which confirm the synergetic effect can be predicted on the basis of the proposed equations which include the values of the mole fraction of surfactant in the mixed micelle and excess Gibbs energy of micellization of SDDS and SDS. Knowing the values of mole fractions of surfactants in the mixed micelle, it is also possible to calculate the volume change of surfactants after the micellization process.
通过表面张力、密度和电导率测量研究了混合阴离子/阴离子表面活性剂溶液（即十二烷基硫酸钠（SDDS）和癸基硫酸钠（SDS））的胶束化热力学。所得结果表明，临界胶束浓度的值强烈依赖于混合物的组成，并且基于罗森和维勒纽夫方法计算的混合胶束中表面活性剂的摩尔分数与本体相中的不同。本体相中SDDS和SDS混合物的临界胶束浓度与组成之间的线性关系存在小的负偏差、分子相互作用参数值、活度系数以及基于罗森和维勒纽夫方法计算的混合胶束形成的过量吉布斯自由能，以及基于布兰克施泰因的MT理论的计算结果证明，SDDS和SDS水溶液的混合胶束形成中存在协同作用。还发现，这两种表面活性剂混合物的胶束化标准吉布斯自由能的值证实了协同效应，可以根据所提出的方程进行预测，这些方程包括混合胶束中表面活性剂的摩尔分数值以及SDDS和SDS的胶束化过量吉布斯自由能。知道混合胶束中表面活性剂的摩尔分数值后，还可以计算胶束化过程后表面活性剂的体积变化。
