Self aggregation of fluorocarbon surfactants and fluorocarbon- hydrocarbon surfactant mixtures
1999 (English)Doctoral thesis, comprehensive summary (Other academic)
The aggregation and phase behavior of fluorocarbon surfactants in micellar, and liquid crystalline phases, and micellization in nonideal mixed fluorocarbon-hydrocarbon surfactant system have been investigated by means of a variety of techniques.
The demixing in mixed surfactant systems was studied in the dilute solution region by using time-resolved fluorescence quenching measurements. It was found that the effectively repulsive interaction between hydrocarbon-fluorocarbon lead to a demixing into separate populations of CH-rich and CF-rich surfactant micelles in mixtures of cetyltrimethylammonium chloride (C16TAC) and 1,1,2,2-tetrahydroperfluorodecyl pyridinium chloride (HFDePC) and in mixtures of lithium perfluorononanoate (LiPFN) and lithium dodecyl sulfate (LiDS).
The aggregation behavior of the cationic fluorocarbon surfactants 1,1,2,2-tetrahydroperfluoroalkylpyridinium chloride and 2 - hydroxy - 1,1,2,3,3 - penta-hydroperfluoroalkyldiethylammonium chloride in aqueous solution has been studied using cryo-transmission electron microscopy. Similar to hydrocarbon surfactants, the fluorocarbonsurfactants self-assemble into various aggregates such as micelles, threadlike micelles, vesicles and other lamellar aggregates. The fluorocarbon surfactants have a larger propensity for forming structures with less curvature than the corresponding hydrocarbon surfactants.
The phase behavior of HFDePC in water has been studied using small-angle X-ray and 2H NMR spectroscopy as the main techniques. The following phase sequence was found: micellar, hexagonal, rectangular and trigonal with increasing surfactant concentration. The fluorocarbon surfactant prefers to form intermediate phases instead of a cubic phase. The occurrence of the intermediate-phases is more extensive in the phase diagram in comparison to a cationic hydrocarbon surfactant of similar hydrophobicity.
Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 1999. , 49 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 481
Research subject Physical Chemistry
IdentifiersURN: urn:nbn:se:uu:diva-1006ISBN: 91-554-4564-0OAI: oai:DiVA.org:uu-1006DiVA: diva2:160540
1999-11-12, Svedberg lecture hall at the Institute of Chemsitry, Uppsala University, Uppsala, 10:15