Surface tension and fluorescence studies of polysaccharide-surfactant solutions: Agar-CTAB

2445-2449The interaction of CTAB (cetyl trimethylammonium bromide) with the agar has been investigated by surface tension and fluorescence measurements. The plots of the surface tension versus concentration of the surfactants for different polymer concentrations show interesting features of the polymer surfactant binding. The binding capacities of CTAB are found to be dependent on the polysaccharide concentrations. These results are interpreted in terms of a polymer surfactant complex of micelle formed by binding between the surfactant ions and the polymer. The surface tension studies show that the 218 mmol CTAB could be bound to the galactose-anhydrogalactose unit of agar. Fluorescence measurements using pyrene as a photophysical probe have been carried out for agar and CTAB mixtures. The interactions between the neutral agar and cationic CTAB leads to formation of pre-micelles at surfactant concentration lower than CMC (0.9585 mM/L) of CTAB. The aggregation process is caused by the electrostatic attraction. It has been proved, using pyrene fluorescence measurements methods, that CTAB forms induced micelles at concentrations smaller than those needed to form micelles in aqueous solution