POLYELECTROLYTE POLY(TERT-BUTYL ACRYLATE)-BLOCK-POLY(2-VINYLPYRIDINE)MICELLES IN AQUEOUS-MEDIA

Poly(tert-butyl acrylate)-block-poly(2-vinylpyridine), PBA-b-PVP, was prepared by living anionic polymerization. Polymolecular spherical mic elles with compact hydrophobic PEA cores and protonated PVP shells in acid water were prepared by a dialysis from organic-aqueous mixtures a nd are stable if the pH is less than pH 4.8. The stretching of the PVP blocks in shells depends on pH and ionic strength of the solution and decreases significantly in a narrow pH region below 4.8. Small hydrop hobic molecules, such as benzene, may be solubilized into micellar cor e swelling the core and releasing the segmental mobility of core-formi ng blocks. Two fluorimetric techniques for determination of pyrene par titioning between micelles and the aqueous phase were used. The first method is based on measurements of the ratio of intensities of the fir st and third vibrational bands, I-1/I-3, in the emission spectra of py rene solubilized in a micellar solution as a function of micellar conc entration. The second method is based on the quenching of fluorescence from solubilized pyrene by thallium salts. The two experimental techn iques yield close values of the apparent partition coefficient, K-app = 1.3 x 10(5) and 1.1 x 10(5), respectively.