Investigation of the micellar growth of 1-dodecylpyridinium chloride in aqueous solution of phenol

Viscosity and conductivity measurements have been made, in a series of concentrations and temperatures, to study the effect of phenol on the micellar growth of 1-dodecylpyridinium chloride (DPC) up to very high surfactant concentration. From the data the first and second critical micelle concentrations, cmc1 and cmc2, and the degree of counter-ion binding, β, of the micelles were determined. The focus has been on finding the effect of high surfactant concentration and various additive concentrations on the growth of DPC micelles at different temperatures which has been correlated with the size and shape of micelles formed. The results indicate that (i) the shape transition of micelles from sphere-to-rod occurs at high DPC concentration, (ii) both micelle formation and micellar growth are accelerated by phenol due to its solubilization into the micelles, and (iii) temperature plays an important role in de-micellization, thus increasing cmc1 and cmc2, in addition to impeding micellar growth.