Aggregation Behavior of Hydrocarbon and Fluorocarbon Surfactants Mixtures

MARÍA FLORENCIA TORRES; MARIANA ADELA FERNÁNDEZ; RITA HOYOS DE ROSSI

Santiago de Compostela, España

Simposio; II Simposio Iberoamericano de Química Orgánica; 2010

Fluorinated surfactants are characterized by larger surface activity and chemical stability than the corresponding hydrocarbon-type compounds. Their unique properties make them very interesting for practical applications as well as for theoretical studies of micellar systems. They have been proposed for the utilization in biomedical applications, such as artificial blood formulations, oxygen transport systems3 and controlled drugs liberation. Besides, they are used as adhesives, cleaners, and in herbicides and cosmetics formulations. They have been proposed for the utilization in biomedical applications, such as artificial blood formulations, oxygen transport systems3 and controlled drugs liberation. Besides, they are used as adhesives, cleaners, and in herbicides and cosmetics formulations. Mixed surfactants are of great interest in order to improve the desired solution properties using smaller amount of material and so decreasing the contamination of the environment. There is a great controversy in the literature regarding the microscopic pseudophase behavior of aqueous mixtures of fluorocarbon and hydrocarbon surfactants. Here we report on the behavior of mixtures of perfluorooctanoic acid with the non ionic surfactant polyoxyethylene(23)lauryl ether (Brij-35) and perfluorononanoic acid with sodium dodecylsuphate . The critical micellar concentration (cmc) of mixtures of several composition (molar fraction of the perfluorinated derivative from 0.1 to 0.9) were determined by different techniques, namely surface tension, 19F NMR and/or kinetic measurements. These two mixtures behave very different, with the non-ionic/ionic system two cmc values were determined at all compositions tested, while the ionic surfactants give only one value under all conditions. The results indicate that in the former case two different types of aggregates are formed under certain conditions whereas in the second system only one type of micelles are formed. From the results it is not possible to establish whether there is or not intramicelar segregation in mixtures of perfluorononanoic acid with sodium dodecylsulphate. These two mixtures behave very different, with the non-ionic/ionic system two cmc values were determined at all compositions tested, while the ionic surfactants give only one value under all conditions. The results indicate that in the former case two different types of aggregates are formed under certain conditions whereas in the second system only one type of micelles are formed. From the results it is not possible to establish whether there is or not intramicelar segregation in mixtures of perfluorononanoic acid with sodium dodecylsulphate. These two mixtures behave very different, with the non-ionic/ionic system two cmc values were determined at all compositions tested, while the ionic surfactants give only one value under all conditions. The results indicate that in the former case two different types of aggregates are formed under certain conditions whereas in the second system only one type of micelles are formed. From the results it is not possible to establish whether there is or not intramicelar segregation in mixtures of perfluorononanoic acid with sodium dodecylsulphate. These two mixtures behave very different, with the non-ionic/ionic system two cmc values were determined at all compositions tested, while the ionic surfactants give only one value under all conditions. The results indicate that in the former case two different types of aggregates are formed under certain conditions whereas in the second system only one type of micelles are formed. From the results it is not possible to establish whether there is or not intramicelar segregation in mixtures of perfluorononanoic acid with sodium dodecylsulphate.