Study of Polystyrene-Block-Poly(Methyl Methacrylate) Micelles by Size Exclusion Chromatography/Low Angle Laser Light Scattering. Influence of Copolymer Composition and Molecular Weight

Abstract

Results of size exclusion chromatography study of the micellar systems polystyrene-block-poly(methyl methacrylate) in the mixed solvent 1,4-dioxane/cyclohexane are reported and the behaviour of copolymers with different overall molecular weight and chemical composition is compared. At higher content of cyclohexane, the effect of the solute trapping in the column due to the adsorption of the unimer on the packing was observed. This effect was more pronounced for the lower molecular-weight copolymers as compared with the higher molecular-weight ones and was found to depend significantly on the thermodynamic quality of solvent (eluent). Experiments in 1,4-dioxane/70 vol.% cyclohexane showed strong influence of unimer—micelles re-equilibration in the column on the resulting chromatograms, especially for the micellar systems of the lower molecular-weight copolymers. For the copolymers of higher molecular-weight, the micelles dissociation in the column was reduced probably due to the more entangled and compact cores of micelles.