ИСТИНА

The interaction of micelles of polyisobutylene-block-poly(sodium methacrylate) diblock copolymers, PIB(X)-b-PMANa(Y) (X = 20, Y = 100, 280, 425; X and Y are the number-average degrees of polymerization of the hydrophobic and the polyelectrolyte blocks, respectively) with strong cationic polyelectrolytes was examined by means of turbidimetry, analytical ultracentrifugation, and fluorescence spectroscopy (with the use of pyrene as a fluorescent probe). Water-soluble interpolyelectrolyte complexes (IPECs) were shown to be generated at pH > 6.5 if the interacting oppositely charged polymeric components are taken in a certain non-equivalent charge ratio Z = [+]/[-], Z < Z* < 1. The results obtained by means of fluorescence spectroscopy and dynamic light scattering suggest that particles of such IPECs can be considered as onion-like micelles, each containing a hydrophobic PIB core surrounded by a water-insoluble complex shell assembled from coupled fragments of the oppositely chraged polymeric components and an ionic corona built up from fragments of the PMANa blocks not involved in the interpolyelectrolyte complexation. A response of the micellar IPECs to thw variation of the ionic strength in the surrounding solution was examined. In the contrast to common non-stoichiometric water-soluble IPECs resulting from the interaction of PMANa with the corresponding cationic polyelectrolytes, an increase of the concentration of NaCl in solutions of such IPECs was not accompanied by a pronounced decrease of the values of Z*. This difference is hypothesized to be associated with peculiarities of the structure of the micellar IPECs, that is, with a considerably non-uniform distribution of cationic macromolecules in polyelectrolyte coronas of the copolymer micelles. At high ionic strengths of the surrounding solution ([NaCl] > 0.5 M), the micellar IPECs were found to dissociate to the individual copolymer micelles and cationic macromolecules due to screening effect of small ions.