Study of Micellization Behavior of Some Alkyldimethylbenzyl Ammonium Chloride Surfactants in the Presence of Polymers

Abstract

The micellization behavior of homologous series of cationic surfactants tetradecyl- (C14BCl), hexadecyl- (C16BCl) and stearyldimethyl-benzyl ammonium chloride (C18BCl) in water and in aqueous solutions of polymers such as polyvinyl pyrrolidone (PVP) and polyethylene glycols (PEG-20 and PEG-06) has been studied at 298.15 K using the conductometric method. The same method has also been used to study the mixed systems, that is, C16-C14BCl, C18-C16BCl, and C18-C14BCl over the whole mole fraction range of the higher chain length surfactant at 298.15, 308.15, and 318.15 K in water and in presence of 0.5 and 1.0% PVP by volume at 298.15 K. From these measurements various micellar parameters like critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization (ψ), and standard free energy of transfer () have been calculated. The CAC and values were found to decrease with increase in polymer concentration whereas PSP values were found to remain constant except in the case of C14BCl where PSP values were found to increase with polymer concentration. The regular solution approach has been applied to determine the mixed micelle mole fraction (X) and the interaction parameter (β). These parameters have also been discussed in terms of micelle-polymer interactions. The combination C16-C14BCl shows synergism at all the studied temperatures in aqueous solution whereas remaining combinations show antagonism (except for C18-C16BCl at 318.15 K). In presence of PVP, the binary mixtures show antagonistic behavior which increases with increase in PVP concentration.