Effects of Micellar Charge Density on the Coefficient of the Corrin–Harkins Relation

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• 作者：Kakehashi ; Rie ; Takeda ; Tokuji ; Maeda ; Hiroshi
• 关键词：Corrin&ndash ; Harkins relation ; mixed micelles ; micellar charge density ; dodecyldimethylamine oxide ; counterion binding ; titration of micelles ; the Gibbs&ndash ; Duhem relation
• 刊名：Journal of Colloid and Interface Science
• 出版年：2002
• 出版时间：September 1, 2002
• 年：2002
• 卷：253
• 期：1
• 页码：238-240
• 全文大小：71.1 K

文摘

Effects of the micelle composition (ionic species fraction α_M) on the coefficient of the Corrin–Harkins relation (k_CH) of ionic/nonionic mixed micelles were examined in the case of dodecyldimethylamine oxide. Long alkyl chain amine oxides exist either in the nonionic or the cationic (protonated form) species depending on the pH of solutions and hence the control of the micelle composition near the critical micelle concentration (cmc) is possible by adjusting the pH of the solutions. On the basis of the cmc data from the surface tension measurements and the hydrogen ion titration curves, we evaluated the k_CH values as a function of the micelle composition α_M for the first time. The obtained k_CH values were compared with the degree of the counterion binding, θ, in the solutions without added salt. The k_CH values increased with α_M, and were approximately identical with θ for α_M>0.4. In the range α_M<0.4, it is likely that θ is greater than k_CH. An empirical relation proposed by D. G. Hall et al. (“Mixed Surfactant Systems,” Am. Chem. Soc., Washington, D.C. 1992) on the relation between θ and the micelle composition was also compared with these experimental results. Experimental values, k_CH and θ, followed the empirical relation for α_M>0.4; however, both k_CH and θ increased steeply in the range α_M 0.25–0.3.