Effect of temperature on critical micelle concentration and thermodynamic behavior of dodecyldimethylethylammonium bromide and dodecyltrimethylammonium chloride in aqueous media
Effect of temperature on critical micelle concentration and thermodynamic behavior of dodecyldimethylethylammonium bromide and dodecyltrimethylammonium chloride in aqueous media
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DOI：
10.1016/j.colsurfa.2004.12.038
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发表时间：
2005-03-21
影响因子：
5.2
通讯作者：
Dham, S
中科院分区：
文献类型：
--
作者：
Mehta, SK;Bhasin, KK;Dham, S
研究了阳离子表面活性剂十二烷基二甲基乙基溴化铵和十二烷基三甲基氯化铵在288.15~308.15 K温度范围内的胶束行为，通过不同温度下电导率的测定，确定了胶束的临界胶束浓度和电离度。从反离子效应和烷基链增加两个方面分析了DDAB和DTAC的CMC行为，并与DTAB的结果进行了比较。应用荷电准相分离模型估算了胶束S茎的热力学参数(G(M)(O)、H-m(O)和S-m(O))。在较低的温度下，DDAB的胶束化是由熵驱动的，而在较高的温度下，胶束化是由焓驱动的。在DTAC的情况下，在整个温度范围内只有熵效应起主导作用。(C)2004爱思唯尔B.V.保留所有权利。
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.