Mixed Micellization and Interfacial Properties of Ionic Liquid-Type Imidazolium Gemini Surfactant with Amphiphilic Drug Amitriptyline Hydrochloride and its Thermodynamics.

The thermodynamics of mixed micellization of amitriptyline hydrochloride (AMT) with ionic liquid-type imidazolium gemini surfactant ([C-4-Cim] Br), was investigated at different mole fractions and temperatures by surface tension measurements. The deviation of the critical micelle concentration (CMC) from the ideal critical micelle concentration (CMC *), micellar mole fraction ( $$X_{1}^{m}$$ ) from ideal micellar mole fraction ( $$X_{1}^{\text{ideal}}$$ ), the values of interaction parameter ( $$\beta$$ ) and activity coefficients ( $$f_{i}$$ ) (for both mixed micelles and mixed monolayer) explained the non-ideal behavior (i.e., synergistic behavior) of binary mixtures. The excess free energy (∆ G) for the AMT-[C-4-Cim] Br binary mixtures explained the mixed micelles stability in comparison to micelles of [C-4-Cim] Br and pure AMT. Interfacial parameters, i.e., Gibbs surface excess ( $$\varGamma_{\hbox{max} }$$ ), minimum head group area at air/water interface ( $$A_{\hbox{min} }$$ ), free energy of micellization ( $$\Delta G_{m}^{o}$$ ), and standard Gibbs energy of adsorption (∆ G) were also evaluated for the systems. The standard entropy of adsorption (∆ S) was found higher than the standard entropy of micellization (∆ S) at all mole fractions of AMT ( α). [ABSTRACT FROM AUTHOR]