Influence of ionic and nonionic hydrotropes on micellar behavior of a cationic gemini surfactant butanediyl-1,4-bis(dimethylcetylammonium bromide)

Micellization of binary systems of a cationic gemini surfactant butanediyl-1,4-bis(dimethylcetylammonium bromide) (16-4-16) and cationic/nonionic hydrotropes (aniline-hydrochloride, 2-methylanilinehydrochloride, 4-methylanilinehydrochloride, hydroxybenzene, 1,3-benzenediol, benzene-1,2,3-triol) have been studied using a conductometric technique. The critical micelle concentrations (cmc) for different mixing mole fractions at different temperatures have been calculated. To explain and compare the results, theoretical models of Clint, Rubingh and Motomura have been used to obtain the ideal cmc, mixed micelle composition, interaction parameters (βm), free energies of micellization, and activity coefficients. The mixtures show nonideal behavior and the interactions between the surfactants and the hydrotropes are synergistic in nature which is confirmed by high negative βm values and low values of the activity coefficients. Thermodynamic parameters were also obtained from the temperature dependence of the cmc values.

Variations of βm versus mole fraction of hydrotrope (α1) in various hydrotrope–surfactant mixtures at different temperatures. Filled symbols are for aniline hydrochloride (cationic) and open symbols for 1,3-benzenediol (nonionic) hydrotroes.Figure optionsDownload high-quality image (72 K)Download as PowerPoint slideHighlights
► Physico-chemical properties of gemini surfactant butanediyl-1,4-bis(dimethylcetyl ammonium bromide) are modified by interaction with cationic and nonionic hydrotropes.
► The mixtures show nonideal behavior and the interactions between the surfactants and the hydrotropes are synergistic in nature.
► The cmc increases with the rise in temperature whereas (βm) values decrease.
► Excess free energy (ΔmixGE) and the respective interaction parameter (βm) values indicate stable mixed micellar systems.