INTERACTION BETWEEN CETYL PYRIDINIUM CHLORIDE AND WATER-SOLUBLE POLYMERS IN AQUEOUS-SOLUTIONS

The interaction between cetyl pyridinium chloride and different-molecu lar-weight poly(vinylpyrrolidone) (PVP) and poly(ethylene glycol) (PEG ) polymers has been investigated by means of electrical conductivity a nd fluorescence probing. No interaction between the low-molecular-weig ht PVP polymers and the surfactant was detected, whereas a significant interaction was observed between high-molecular-weight PVP polymers o r PEG polymers and cetyl pyridinium chloride. The results indicate tha t polymer-surfactant aggregates start to form at a surfactant concentr ation higher than the critical micelle concentration of micelles witho ut polymers. In contrast, the degree of ionization and the interface p olarity decrease as compared with values of micelles without polymers. The Gibbs free energy associated with the interaction was also calcul ated. The values show that the addition of polymers stabilizes polymer -surfactant aggregates. (C) 1997 Academic Press.