Mixed Micellization Between an Antidepressant Drug Imipramine Hydrochloride and Surfactants (Conventional/Gemini) at Different Temperatures and Compositions

The micellization behavior of an amphiphilic antidepressant drug imipramine hydrochloride (IMP) in the presence of a conventional (CTAB) and three gemini (16-s-16, s = 4–6) cationic surfactants has been studied at different temperatures and compositions by conductometry. The experimental and ideal critical micelle concentrations, cmc and cmcid, values indicate mixed micelle formation between the components. The micellar mole fractions of surfactants (X1Rub\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ X_{1}^{\text{Rub}} $$\end{document}, X1M\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ X_{1}^{\text{M}} $$\end{document}, X1Rod\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ X_{1}^{\text{Rod}} $$\end{document} and X1id\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ X_{1}^{\text{id}} $$\end{document}), calculated using different theoretical models, show greater contribution from the surfactants. The interaction parameter (β) is negative at all temperatures and at all compositions indicating attractive interactions. Activity coefficients (f1 and f2) are always less than unity reflecting nonideality in the systems. Thermodynamic parameters which were also evaluated suggest dehydration of the hydrophobic part of the drug at higher temperatures.