| Abstract
| - Unimolecular micelle formation is investigated by means of lightscattering for poly(methylmethacrylate)-graft-polystyrene copolymers with low graftedchain densities in dilute solution of mixedselective solvents. Molecular weights of poly(methylmethacrylate) (PMMA) backbone and polystyrene(PS) branch are about 6 × 106 and 9 × 103 gmol-1, respectively, and the grafted chaindensity rangesfrom 6 to 17 wt % in terms of PS composition. The mixed solventsare marginally good solvents forPMMA and are nonsolvents for PS. From the results of static anddynamic light scattering measurementsas a function of temperature and solvent composition, it isdemonstrated that, at higher branch densitiesand lower temperatures, the rod like unimolecular micelles are formed,made of a few linearly connectedflowers with small cores of associated PS branches and petals of PMMAbackbone chain. The number ofpetals per flower increases with increasing branch density anddecreasing solubility of solvents for PMMA.On the other hand, at the lowest branch density of 6 wt %,instead of unimolecular micelle formation,intermolecular associations take place, even at low copolymerconcentration.
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