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Mixed micellar aggregates of nonionic surfactants with short hydrophobic tails

Mixed micelle formation by aqueous mixtures of pentaethylene glycol monohexyl ether (C 6E 5) and diethylene glycol monohexyl ether (C 6E 2) has been investigated by determining the temperature-composition phase diagrams and measuring the intradiffusion coefficients. In binary aqueous solutions, C 6E...

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Bibliographic Details
Published in:Journal of molecular liquids 2002-09, Vol.100 (3), p.241-253
Main Authors: D'Errico, Gerardino, Ciccarelli, Donato, Ortona, Ornella, Vitagliano, Vincenzo
Format: Article
Language:English
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Summary:Mixed micelle formation by aqueous mixtures of pentaethylene glycol monohexyl ether (C 6E 5) and diethylene glycol monohexyl ether (C 6E 2) has been investigated by determining the temperature-composition phase diagrams and measuring the intradiffusion coefficients. In binary aqueous solutions, C 6E 5 shows a high tendency to micellize, while C 6E 2, because of its too short hydrophilic head, presents a macroscopic phase separation in a water-rich and a surfactant-rich phases. The temperature-composition phase diagrams obtained for the ternary water-C 6E 5C 6E 2 mixtures present a micellar region in which both surfactants co-aggregate. The dimensions of this micellar region depend on the relative ratio between the two surfactants molalities. By analysing the micelle intradiffusion coefficient, measured through the PGSE-NMR technique, the hydrodynamic radius of the aggregates has been estimated at 25 °C. It is similar to that of triethylene glycol monohexyl ether (C 6E 3) in binary aqueous solution. The experimental evidences suggest that in mixed ethoxylated surfactants the micellar behaviour is mainly determined by the mean number of ethoxylic units per surfactant molecule, independently of their distribution.
ISSN:0167-7322
1873-3166
DOI:10.1016/S0167-7322(02)00045-4