Structural chemical transformations of non-stoichiometric polyelectrolyte complexes in water-salt solutions☆

Abstract A study has been made of the behaviour of non-stoichiometric polyelectrolyte complexes formed by sodium polyacrylate and linear polyethyleneimine in water-salt solutions. It is shown that phase separation is preceded by deep structural-chemical transformations occurring in particles of these complexes in solution in the presence of a low molecular electrolyte. Successive opening of interchain salt bonds is accompanied by a marked compactization of complex particles, with subsequent disproportionation into two polycomplexes differing in their composition — one approximating to the stoichiometric composition, and the other with a diminished polyethyleimine concentration compared with the initial content. Phase separation takes place as a result of conformational transitions and chemical reactions of macromolecular exchange occurring in homogeneous water-salt solutions of the nonstoichiometric polyelectrolyte complexes.