Transition from antagonistic to synergistic interaction in mixed micellar system by increase in alkyl chain length of alkyl trimethylammonium bromide

Herein, the electrical conductivity technique used to measure the critical micelle concentration (cmc) for pure cationic surfactants (Dodecyl/cetyltrimethylammonium bromides) and phenothiazine drug (Promethazine hydrochloride), as well as their different mole fractions in 10-3 mol/kg 1-methyl-3-octylimidazolium chloride (C8mim.Cl) at different temperatures. By using the cmc values the regular solution theory used to evaluate the micellar mole fraction for DTAB/CTAB-PMT mixed systems. The clint's model used to calculate the ideal critical micelle concentration (cmc*) that helps to evaluate the ideal micellar mole fraction for studied mixed systems, both explain the deviation from ideality. In addition, interaction parameter beta m helps to confirm the nature of interaction (either antagonistic or synergistic) for the studied systems. The calculated parameters confirm a transition in the binding nature from antagonistic to synergistic with the increase in alkyl chain length of cationic surfactant i.e., component of the binary mixed system. The ease of micellization for the studied systems discussed by the standard Gibb's energy of micellization (Delta G0m), as well as the standard enthalpy and standard entropy of micellization were (Delta H0m) and (Delta S0m), respectively to discuss the stability of the studied systems.

Automated summary

In this study, the electrical conductivity technique was used to measure the critical micelle concentration (cmc) for pure cationic surfactants and a phenothiazine drug in different mole fractions and temperatures. The regular solution theory and clint's model were employed to evaluate the micellar mole fraction and ideal critical micelle concentration (cmc*) for the mixed systems. The results showed a transition in the binding nature from antagonistic to synergistic with the increase in alkyl chain length of the cationic surfactant. Additionally, the ease of micellization and stability of the systems were discussed using the standard Gibbs energy, enthalpy, and entropy of micellization.