Аннотация:Dissociative stability of interpolyelectrolyte complexes fonned by fluorescently labeled polymethacrylate anions and poly(N-ethyl-4-vinylpyridinium) cations was studied in aqueous salt-containing solutions by fluorescence quenching and velocity sedimentation. It was shown that the dissociation of interpolyelectrolyte complexes in which the degree of polymerization of polyanion is greater than the degree of polymerization of polycation begins at a certain critical concentration of the salt in the solution and proceeds by gradual expulsion of polycations from the complex. It was found that the critical concentration of low-molecular-
mass electrolyte increases with an increase in the chain length of polycation and is almost independent of the degree of polymerization of polyanion and of the initial composition of the interpolyelectrolyte complex. A model that correlates the critical concentration of salt with the fraction of salt bonds that have dissociated in the complex was suggested. Within the framework of this model, the need to consider cooperativity of the dissociation of interpolymer salt bonds was demonstrated.