Mixed micellization of a trisubstituted surface active ionic liquid 1-dodecyl-2,3-dimethylimidazolium chloride [C12bmim][Cl] with an amphiphilic drug amitriptyline hydrochloride AMT: A detailed insights from conductance and surface tension measurements

Abstract

The thermodynamics and interfacial behavior of the mixed micellization of a trisubstituted imidazolium based surface active ionic liquid (SAIL), 1-dodecyl-2,3-dimethylimidazolium chloride [C12bmim][Cl], with an antidepressant amphiphilic drug amitriptyline hydrochloride (AMT) have been studied by employing surface tension measurements at 298.15 K and from conductance at 288.15, 298.15 and 308.15 K. Critical micelle concentration (cmc), degree of ionization (α), and other thermodynamic parameters like Gibbs free energy of micellization (∆Gmic.°), standard enthalpy of micellization (∆Hmic.°) and standard entropy of micellization (∆Smic.°) were derived from conductivity measurements. The respective surface active parameters like surface tension at cmc (γcmc), minimum surface area per ionic liquid molecule (Amin), adsorption efficiency (pC20), maximum surface excess concentration (Гmax), effectiveness of surface tension reduction (Πcmc), and cmc of the mixed systems of SAIL and AMT have been cognized using surface tension measurements. The negative values of ∆Gmic.° and the standard Gibbs free energy of adsorption at the air/water interface (∆Gad.°) indicate the feasibility of the micellization behavior of the mixed systems and confirm the feasibility of drug-SAIL interactions. The micellar interaction parameter (βm) have also been analyzed to get detailed insights of the interactions between the amphiphilic drug and the SAIL by applying theoretical model introduced by Rubingh and Motomura. The negative value of this parameter indicates the presence of synergistic interactions of SAIL-AMT binary mixtures. A comparative study has been done between disubstituted and trisubstituted SAILs and it has been found that the surface activity of trisubstituted SAIL is better than their disubstituted analogue due to the high hydrophobicity and hydrophilicity of trisubstituted SAIL.