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Aggregation Behavior of Perfluorononanoic Acid/Sodium Dodecyl Sulfate Mixtures
Author(s) -
Torres María Florencia,
Rossi Rita H.,
Fernández Mariana Adela
Publication year - 2013
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-013-1452-6
Subject(s) - chemistry , pulmonary surfactant , mole fraction , sodium dodecyl sulfate , pyrene , aggregation number , analytical chemistry (journal) , micelle , hydrocarbon , critical micelle concentration , quenching (fluorescence) , inorganic chemistry , chromatography , fluorescence , organic chemistry , aqueous solution , biochemistry , physics , quantum mechanics
The mixed system of an anionic hydrocarbon surfactant, sodium dodecyl sulfate, and a perfluorinated surfactant, perfluorononanoic acid (PFNA), was investigated by a combination of methods. The critical micellar concentrations (CMC) were determined over a wide range of sample compositions by surface tension, conductivity and UV–visible spectrophotometry using N ‐(4‐nitrophenyl)perfluorononanamide as a molecular probe. The values of CMC obtained by different techniques were in good agreement. In addition, the aggregation numbers were determined in the mixtures with a low content of hydrocarbon surfactant, by measuring the fluorescence quenching of pyrene. The hydrodynamic radii of the aggregates were estimated through the diffusion ordered 19 F‐ and 1 H‐NMR spectroscopy. The values obtained are in agreement with those expected according to the measured aggregation numbers. The analysis of the data with different aggregation models suggests the formation of a non‐ideal mixed micelle that is enriched in the perfluorinated surfactant when its mole fraction increases, and that is practically formed by PFNA only at mole fractions higher than 0.8.