Interaction of triblock-copolymer with cationic gemini and conventional surfactants: A physicochemical study

In the current work, we have examined the interaction activities of Pluronic F-68 with cationic conventional, cetyltrimethylammonium bromide (CTAB), and gemini surfactant, pentanediyl-1, 5-bis(dimethylcetylammonium bromide), (16-5-16) by means of surface tension and conductivity measurements. The critical micelle concentration (cmc) values of pure 16-5-16 and CTAB have been evaluated tensiometrically and conductometrically, while the cmc values of pure F-68 and binary mixtures were determined only from the surface tension plots. Various interfacial and micellar parameters including surface excess concentration (Γmax), minimum area per molecule (Amin), surface pressure at cmc (πcmc), packing parameter (p), and interaction parameter (β) have been estimated and discussed in detail. Various thermodynamic parameters including Gibbs free energy of micellization (), standard free energy of adsorption at the air–water interface (), excess free energy of micellization (ΔGex), and molar free energy at the maximum adsorption achieved at cmc (Gmin) have been calculated.