Formation and Properties of Polystyrene-block-poly(2-hydroxyethyl methacrylate) Micelles

Polystyrene- block -poly(2-hydroxyethyl methacrylate) (PS- b -PHEMA) samples of different molar masses have been synthesized. These polymers formed micelles in THF/cyclohexane mixtures. The change in the hydrodynamic radius and aggregation number of these micelles as a function of cyclohexane volume fraction f c has been investigated. We also report some preliminary fluorescence results of pyrene- and fluorene-labeled PS- b -PHEMA. The increase in energy transfer from fluorene, attached randomly at a density of <5% to the PHEMA block, to pyrene, attached at the junction point between PS and PHEMA, provides a sensitive measure for micelle formation. The energy transfer efficiency in micelles was high, and excimer formation between different fluorene groups was negligible. This will facilitate micellar core size determination by energy migration.