Portet F, Desbene PL, Treiner C
Laboratoire d'Analyse des Systemes Organiques Complexes., Institut Universitaire de Technologie, Universite de Rouen, 43 Rue Saint Germain, Evreux, 27000, France
J Colloid Interface Sci. 1996 Dec 1;184(1):216-26. doi: 10.1006/jcis.1996.0614.
The behavior of two pure alkylethoxylated nonionic surfactants, both as single components and as binary mixtures of various composition, has been studied in solution and at silica/water interfaces. In solution, the variation of cmc with surfactant composition showed large negative and positive deviations from thermodynamic ideality. These results, as obtained from surface tension measurements, may be interpreted by a partial demixing of the micelles into segregated aggregates in the C10E6-rich composition range and by an increased stability of the aggregates in the C14E6-rich domain. Careful determination of individual isotherms of the surfactants either as single components or as components of mixtures was performed at a nonporous silica/water interface using a reversed phase HPLC technique. The pure nonionic surfactants displayed non superimposable isotherms when sufficiently dilute solution can be attained: a single adsorption plateau is observed with the more hydrophobic component, and a two-plateau behavior is obtained with the more hydrophilic compound. Some experiments with the intermediate surfactant C12E6 were also performed showing a single-plateau profile. Experimental confirmation of the demixing process at the silica/water interface was found in the C10E6-rich end of the diagram. However, the larger than usual favorable interaction between the surfactants in the C14E6-end of the diagram could not be deduced directly from the shape of the individual isotherms. The various isotherms were discussed making use of the known properties of these surfactants in solution as micelle-type aggregates and as lamellar phases.
研究了两种纯烷基乙氧基化非离子表面活性剂在溶液中以及在二氧化硅/水界面上的行为，这两种表面活性剂既作为单一成分，也作为各种组成的二元混合物。在溶液中，临界胶束浓度（cmc）随表面活性剂组成的变化显示出与热力学理想状态有很大的负偏差和正偏差。这些通过表面张力测量获得的结果，可以解释为在富含C10E6的组成范围内，胶束部分分离成聚集物，以及在富含C14E6的区域内聚集物稳定性增加。使用反相高效液相色谱技术，在无孔二氧化硅/水界面上仔细测定了表面活性剂作为单一成分或混合物成分的各个等温线。当能达到足够稀的溶液时，纯非离子表面活性剂显示出不可叠加的等温线：疏水性更强的组分观察到单一吸附平台，亲水性更强的化合物则呈现双平台行为。还对中间表面活性剂C12E6进行了一些实验，显示出单一平台特征。在相图富含C10E6的一端发现了二氧化硅/水界面处混合过程的实验证实。然而，相图中富含C14E6一端的表面活性剂之间比平常更强的有利相互作用不能直接从各个等温线的形状推导出来。利用这些表面活性剂在溶液中作为胶束型聚集体和层状相的已知性质，对各种等温线进行了讨论。
