期刊
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
卷 255, 期 1-3, 页码 153-157出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.colsurfa.2004.12.038
关键词
dodecyldimethylethylammonium bromide; dodecyltrimethylammonium chloride; critical micelle concentration; degree of ionization
Micellar behavior of cationic surfactants, dodecyldimethylethylammonium bromide (DDAB) and dodecyltrimethylammonium chloride (DTAC) in aqueous media has been investigated over the temperature range 288.15-308.15 K. The critical micelle concentration (cmc) and degree of ionization (beta) of the micelles were determined from the conductivity measurements at different temperatures. The cmc behavior of DDAB and DTAC was analyzed in comparison with the results of DTAB in terms of effect of counter ion and increase in alkyl chain. Thermodynamic parameters (Delta G(m)(o), Delta H-m(o) and Delta S-m(o)) for the micelle s stem were estimated by applying the charged pseudo-phase separation model. At lower temperatures, the micellization in case of DDAB was found to be entropy-driven while at higher temperatures it was enthalpy-driven. In case of DTAC only entropic effect dominates over the entire temperature range. (c) 2004 Elsevier B.V. All rights reserved.
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