ИСТИНА

The interaction of macromolecular micelles formed in alkaline media by amphiphilic diblock copolymers polyisobutylene-block-poly(sodium methacrylate) containing 20 monomer units in polyisobutylene block and 100, 280, or 425 monomer units in poly(sodium methacrylate) (PMANa) block with a strong cationic polyelectrolyte poly(N-ethyl-4-vinylpyridinium bromide) of DPw = 500 was examined by means of turbidimetry, fluorescence spectroscopy (pyrene was used as a fluorescence probe), and analytical ultracentrifugation. In mixtures containing charges of the polymeric components in non-equivalent ratios Z = [+]/[-] lower than the certain critical value Z < Z* < 1, the formation of particles of water-soluble non-stoichiometric interpolyelectrolyte complexes considerably enriched by carboxylate groups of the anionic copolymers compared to pyridinium groups of the cationic polyelectrolyte was observed. Such particles were found to effectively solubilize pyrene (similarly to the pure macromolecular micelles), this process being accompanied by pronounced quenching of fluorescence of the probe (oppositely to the pure macromolecular micelles). A particle of the formed interpolyelectrolyte complexes was hypothesized to be a peculiar micelles consisting of a two-component hydrophobic nucleus formed by a polyisobutylene core surrounded by a layer of coupled oppositely charged polyelectrolyte fragments and an ionic corona formed by fragments of PMANa blocks not involved in interpolyelectrolyte interaction. The dependencies of Z* on the concentration of low molecular weight salt (NaCl) were obtained for all the copolymers as well as for a reference anionic homopolyelectrolyte PMANa. Whereas for the homopolyelectrolyte the increase in the salt concentration is accompanied by a drastic decrease in the values of Z*, this tendency was either completely absent or only slightly visible for the copolymers. For all the copolymers, the interaction between the macromolecular micelles and the cationic polyelectrolyte was found to be completely suppressed at relatively high salt concentrations ([NaCl] > 0.45 M) due to the screening effect of small ions.