Collect. Czech. Chem. Commun. 1993, 58, 2362-2369

Block Copolymer Micelles in Aqueous Media

Zdeněk Tuzara, Pavel Kratochvíla, Karel Procházkab and Petr Munkc

a Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, 162 06 Prague, Czech Republic
b Department of Physical Chemistry, Charles University, 128 40 Prague 2, Czech Republic
c Department of Chemistry and Biochemistry and Center for polymer Research, The University of Texas at Austin, Austin, TX 78712 U.S.A.


Micellization of di- and triblock copolymers, poly(methacrylic acid)-block-polystyrene and poly(methacrylic acid)-block-polystyrene-block-poly(methacrylic acid), varying in molecular weight and composition, has been studied by static and dynamic light scattering, and sedimentation velocity. Micelles with polystyrene cores were prepared in water-dioxane mixtures, rich in dioxane, and transferred into water-rich mixtures, water, and aqueous buffers via stepwise dialysis. It has been shown that, in dioxane-rich mixtures, the micellar system was in dynamic equilibrium, while in water-rich solvents, water, and aqueous buffers the micellization equilibrium was frozen and micelles behaved like autonomus particles. Under certain conditions, micelles were accompanied by independent large particles. This phenomenon, known from other micellar systems as an "anomalous micellization", is discussed.