ИСТИНА

Electrostatic attraction between oppositely charged macromolecules leads to the formation of interpolyelectrolyte complexes (IPECs). IPECs are of considerable interest due to their numerous promising applications as novel polymeric reagents and materials for industry, ecology, biotechnology, and medicine. The purpose of our research has been to prepare water-soluble IPECs containing alternating copolymers of maleic acid and alkenes as well as to study their properties in aqueous media. Sodium salts of fluorescently labeled poly(maleic acid-alt-ethene) (P(MaNa-alt-Et), Pw = 1300, 5% mole content of pyrenyl labels) and poly(maleic acid-alt-propene) (P(MaNa-alt-Pr), Pw = 200, 3% mole content of pyrenyl labels) were taken as such anionic copolymers while poly(N-ethyl-4-vinylpyridinium bromide) (P(VPEtBr), Pw = 500) was used as a cationic polyelectrolyte. The formation of water-soluble IPECs upon the interaction between the oppositely charged macromolecules was observed if a ratio Z, Z = [+]/[-] (molar concentrations of the charged groups of the corresponding polyelectrolyte components in their mixtures are given in the brackets), was lower than a certain value Z*. The values of Z* (Z* < 0.5) were found to depend on characteristics of the anionic copolymers and to be rather sensitive to variations in the concentration of NaCl. The hydrodynamic characteristics of particles of water-soluble IPECs were determined. The obtained results suggest that such particles are rather compact, their conformation becoming more compact with increasing Z or with increasing concentration of NaCl. Stability of water-soluble IPECs was examined by means of fluorescence technique because pyridinium groups of the cationic polyelectrolyte quench fluorescence of pyrenyl labels of the anionic copolymers upon their contact. The obtained results indicate that dissociation of IPECs proceeds at high concentrations of NaCl ([NaCl] > 0.3 M). This phenomenon can be explained by a screening effect of small ions.