Instituto de Investigaciones en Físico-Química de Córdoba (INFIQC), Facultad de Ciencias Químicas, Departamento de Química Orgánica, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba, Argentina.
Langmuir. 2010 Dec 7;26(23):17858-66. doi: 10.1021/la103330p. Epub 2010 Nov 8.
The mixed system of a nonionic hydrocarbon surfactant, polyoxyethylene (23) lauryl ether (Brij-35), and a perfluorinated surfactant, perfluorononanoic acid, was investigated by a combination of methods. The critical micelle concentrations (cmc's) have been determined over a wide range of sample compositions by fluorescence and UV-visible spectrophotometry using pyrene and N-(4-nitrophenyl) perfluorononanamide, respectively, as molecular probes. The values of the cmc's obtained were considerably different with the two techniques employed. Measurements of the (19)F nuclear magnetic resonance chemical shift of the same mixtures showed two breaks in the plots of Δδ(f) versus molar fraction of the perfluorinated surfactant. Conductivity and surface tension measurements also showed two breaks. The behavior is attributed to the formation of mixed micelles that change their composition when the fraction of the fluorinated compound increases and some segregation of the fluorinated compound takes place at a high total surfactant concentration.
混合体系的非离子型碳氢表面活性剂，聚氧乙烯（23）月桂醚（Brij-35），和全氟表面活性剂，全氟壬酸，进行了调查的组合方法。临界胶束浓度（cmc的）已经确定在广泛的样品组成荧光和紫外可见分光光度法用芘和 N-（4-硝基苯基）全氟壬酰胺，分别作为分子探针。值的 cmc 的得到有很大的不同与所采用的两种技术。测量的（19）氟核磁共振化学位移的相同混合物表明两个突破的情节Δδ（F）对摩尔分数的全氟表面活性剂。电导率和表面张力的测量也显示了两个突破。这种行为归因于形成混合胶束改变其组成时的分数增加的氟化化合物和一些分相的氟化化合物在高总表面活性剂浓度。
