VISCOMETRIC STUDIES ON THE EFFECT OF AMINES IN THE SPHERE-TO-ROD TRANSITION OF AQUEOUS IONIC MICELLES

The effect of n-amines on sphere-to-rod transitions in aqueous micellar solutions of cationic and anionic surfactants was studied by viscosity measurements at various temperatures. The surfactants studied were cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). It was observed that the relative viscosities of concentrated micellar solutions increased abruptly above a certain amine concentration depending upon the nature of the amine. The effect of amines on the activation energy for viscous flow was studied from the temperature dependence of viscosity. A large increase in viscosity and activation energy by the addition of amine has been attributed to the change in the shape of micelles from sphere to rod or sphere to disc-like. The effect of amines on the viscosity and activation energy of anionic micelles was tremendously large as compared to cationic micelles. Charge induced solubilization of amines was responsible for the higher viscosity and activation energy for viscous flow of the SDS micellar solution.