BLOCK COPOLYMER MICELLES IN AQUEOUS-MEDIA

Polystyrene-block-poly(methacrylic acid) and poly(methacrylic acid)-block-polystyrene-block-poly(methacrylic acid) di- and triblock copolymers form micelles with polystyrene cores and poly(methacrylic acid) shells when dissolved in water/1,4-dioxane mixtures, rich in dioxane. These micelles can be transferred into water rich mixtures, into water, and into aqueous buffers by stepwise dialysis. Quasielastic light scattering and sedimentation velocity experiments show that in dioxane rich mixtures exists a dynamic micellization equilibrium, while in dioxane poor solutions and in aqueous buffers the equilibrium is frozen. The process of mixed micelles formation was observed in dioxane rich solutions.