Critical micelle concentrations and interaction parameters of aqueous binary surfactant:ionic surfactant mixtures

Unusual behavior of CMC for binary mixtures of alkyltrimethylammonium bromides: Dependence on chain length difference

“…The usual type of CMC behavior has been also observed with binary systems of surfactants by Lange [31] and Mysels [32], and has been also been shown to follow E = −(1 + β). These results confirm the correctness of our decision not to use Rubingh's equation for the analysis of CMC data because it does not satisfy electroneutrality and it does not consider the electrostatic interaction between a surfactant aggregate and its diffusion layer [25,26]. One must also be aware that the CMC of a mixture of ionic surfactants depends not only on the surfactant composition, but also on the counterion concentration.…”

“…The value of the parameter E for ideal binary mixtures of the surfactants corresponds to about −(1 + β), where β is the binding degree of the counterion [26]. The calculation of these parameters is carried out using only the compounds with the usual CMC behavior, excluding data from those with unusual CMCs.…”

“…When the theory is applied to a mixed micelle, the activity coefficients of the surfactants in the mixed micelle are given by γ m 1 = exp{ω(1 − y) 2 } and γ m 2 = exp{ωy 2 }, where ω is related to the molecular interaction (excess pair molecular interaction) in the mixed micelle. The interaction parameter ω is obtained on the basis of the following equation [26]:…”

“…Without considering the activity coefficient of the micelle, it is difficult to justify the Corrin-Harkins equation [25,26]. One should make the Corrin-Harkins equation satisfy the thermodynamics considerations of the micelle.…”

Micellization and interfacial behavior of binary and ternary mixtures of model cationic and nonionic surfactants in aqueous NaCl medium

“…Akisada et al [34] have shown that the Clint's equation can be used at a constant concentration of counterions. Therefore the experiments were carried out at constant ionic strength.…”