Vlachy, Nina and Arteaga, Alexandro F. and Klaus, Angelika and Touraud, Didier and Drechsler, Markus and Kunz, Werner (2009) Influence of additives and cation chain length on the kinetic stability of supersaturated catanionic systems. Colloids and Surfaces, A: Physicochemical and Engineering Aspects 338 (3), pp. 135-141.
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The stability of mixed surfactant solns. of sodium dodecylsulfate (SDS) with cetyltrimethylammonium bromide (CTAB) and with dodecyltrimethylammonium bromide (DTAB) was studied as a function of time. These specific mixts. are shown to have a soly. temp. below that of pure surfactant solns. in the anionic-rich region. The stability of such supersatd. solns. was studied with and without different additives. Surfactant mixts. without additives are shown to destabilize with time varying between 3 and 28 days, depending on the surfactant ratio. Generally, the stability of soln. increases by increasing the percentage of the anionic surfactant. The variation of the chain length of the cationic surfactant produces a large effect on the stability of such mixed surfactant systems. The presence of simple electrolytes decreases, while the addn. of middle-chain alcs. increases its stability. Bluish solns. corresponding to a vesicular region were obsd. at ratios close to equimolarity in samples without salt, and in the anionic-rich region upon the addn. of middle-chain alcs. Fluorescence and dynamic light scattering measurements showed that the destabilization of the solns. is not due to the formation of bigger aggregates, but rather due to a shift of the equil. between micelles and monomers, leading to the liberation of monomers, which ppt. The lifetime of vesicles and micelles can therefore be controlled by varying the compn. of the surfactant solns. and by additives. Controlling the pptn. phenomena is of importance for a large no. of industrial processes, such as oil/solute recovery processes after extns. or chem. reactions.
|Institutions:||Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > Prof. Dr. Werner Kunz|
|Keywords:||sodium dodecyl sulfate dodecyltrimethylammonium cetyltrimethylbromide bromide surfactant micelle|
|Subjects:||500 Science > 540 Chemistry & allied sciences|
|Refereed:||Yes, this version has been refereed|
|Created at the University of Regensburg:||Yes|
|Deposited On:||18 May 2012 08:12|
|Last Modified:||18 May 2012 08:12|