ИСТИНА

Lightly cross-linked polyelectrolyte networks are very attractive objects of investigations. Polycomplex gels formed as a result of interactions between polyelectrolyte networks and different oppositely charged species, such as linear polyelectrolytes, surfactants, proteins have been studied thoroughly. Different features determined by the cross-linked nature of a complex component were revealed. In this work, interactions between anionic network and water soluble non-stoichiometric interpolyelectrolyte complexes (NIPCs) formed by star-like poly(acrylic acid) and linear polyctaion were studied. Lightly cross-linked sodium poly(acrylate) or sodium poly(2-acrylamido-2-methylpropanesulfonate) were used as a polyelectrolyte network. NIPCs contain star-like poly(acrylic acid) and (poly(N-ethyl-4-vinylpiridinium bromide) or poly(2,5-ionen bromide) as a polycation. The composition of NIPC, φ, i.e. the ratio of mole amount of positively charged amino groups to mole amount of negatively charged carboxylic groups was φ = 0.2-0.3. Such complexes are water soluble due to the excess of charged groups of star-like polyelectrolyte. In the triple systems studied, the star-like polyelectrolyte competes with a network for the binding with a linear polycation. It was found that sulfo-containing polyelectrolyte gel can sorb linear polycations from NIPC aqueous solutions with the formation of a new polycomplex (network-polycation). This process is accompanied with a gel collapse. Star-like poly(acrylic acid) previously bound with a linear polyctaion is released from NIPC. In contrast to sulfo-containing network, in the case of carboxylic gel, the substitution reaction does not proceed. Thus, in the systems described, the chemical nature of polyanionic network determines the direction of the substitution reaction.