Effect of temperature on critical micelle concentration and thermodynamic behavior of dodecyldimethylethylammonium bromide and dodecyltrimethylammonium chloride in aqueous media

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 255; no. 1; pp. 153 - 157
• Main Authors: Mehta, S.K., Bhasin, K.K., Chauhan, Renu, Dham, Shilpee
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 21.03.2005; Elsevier
• Subjects: Chemistry; Colloidal state and disperse state; Critical micelle concentration; Degree of ionization; Dodecyldimethylethylammonium bromide; Dodecyltrimethylammonium chloride; Exact sciences and technology; General and physical chemistry; Micelles. Thin films; Degree of ionization; Dodecyldimethylethylammonium bromide; Critical micelle concentration; Dodecyltrimethylammonium chloride; Critical property; Electrical conductivity; Enthalpy; Cationic surfactant; Temperature effect; Micelle; Entropy; Ionic surfactant; Thermodynamics; Micellar critical concentration; Alkyl; Quaternary ammonium compound; Temperature measurement; Ionization; Thermodynamic parameter; Phase separation; Counter ion; Models; Aqueous solution; Critical temperature; Thermodynamic properties; Physicochemical properties; Comparative study; Micellization
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2004.12.038

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 ( β) 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 ( Δ G m ° , Δ H m ° and Δ S m ° ) for the micelle system 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.