Micellization and Gelation of Aqueous CTAB and TX-100 in the Presence of Additives, 1- and 2-Naphthols : a Viscometric Study

The properties of aqueous solutions of CTAB and TX-100 have been investigated in the presence of additives, viz., 1- and 2-naphthols by viscosity measurements. Unlike binary systems, relative viscosity versus concentration plots show well defined break points near cmc's in the presence of additives. Addition of 1-naphthol decreases the cmc values of both the surfactants while 2- naphthol decreases the cmc of TX-100 but increases that of CTAB slightly. The threshold additive concentration for gel formation (tac) by 1- and 2-naphthols are 3.2 mmol/lit and 2.4 mmol/lit respectively for CTAB whereas, they are 1.0 mmol/lit and 0.6 mmol/lit respectively for TX-100. The surfactant concentrations are, however, much below that of the reported concentration at which spheri- cal-to-rod micelle transition occurs. The large deviation of the cmc value of TX-100 in the presence of both the additives has been explained in terms of the greater hydrophobic hydration and hydrogen bonding.