DETERMINATION OF THE MICELLE ARCHITECTURE OF POLYSTYRENE POLY(4-VINYLPYRIDINE) BLOCK-COPOLYMERS IN DILUTE-SOLUTION

Block copolymers consisting of polystyrene (PS) and poly(4-PVP) with varying chain lengths are synthesized via anionic polymerization. When these block copolymers are dissolved in selective solvents (solvents for PS), well-defined micelles with respect to their size and size distribution are formed. These micelles are characterized by static and dynamic light scattering. The characterization reveals that the micelles exhibit spherical or prolate morphology with a size in the range 20 less-than-or-equal-to r(H) less-than-or-equal-to 100 nm. Size and shape depend only on the block molecular weights and the solvent used but exhibit no significant concentration dependence. In certain solvents, the observation of scattering peaks indicates the formation of intermicellar ordering on the scale of the wavelength of light. Viscometric experiments reveal that the block copolymer micelles are unstable under shear applied in common viscometer tubes and decompose to the primary block copolymers. The associated structure, however, is quickly recovered.