Institute Investigaciones En Fisico Quimica Of Cirdoba Infiqc

Buenos Aires, Argentina

Institute Investigaciones En Fisico Quimica Of Cirdoba Infiqc

Buenos Aires, Argentina

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Torres M.F.,Institute Investigaciones En Fisico Quimica Of Cirdoba Infiqc | Sales P.S.,Institute Investigaciones En Fisico Quimica Of Cirdoba Infiqc | De Rossi R.H.,Institute Investigaciones En Fisico Quimica Of Cirdoba Infiqc | Fernandez M.A.,Institute Investigaciones En Fisico Quimica Of Cirdoba Infiqc
Langmuir | Year: 2010

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 (cmcs) 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 cmcs obtained were considerably different with the two techniques employed. Measurements of the 19F nuclear magnetic resonance chemical shift of the same mixtures showed two breaks in the plots of Δδf 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. © 2010 American Chemical Society.

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