Formation of polyelectrolyte complexes in a polycarboxybetaine/weak polyanion system

Polycarboxybetaines - polymers containing a substituted ammonium moiety and a carboxylate group in every monomer units - show in aqueous solutions a pH-dependent intramolecular charge interactions. Here, we show that despite of this intramolecular charge effect mixing positively charge polycarboxybetaine and oppositely charged poly(maleic acid-co-propene) can yield polyelectrolyte complexes (PEC). Dynamic light scattering and viscometry has proved formation of highly swollen PEC nanoparticles with sizes in the range of 5-8 nm at n-/n+ ratio from 0.6 to 1.0. Significant difference in charge densities and molecular dimensions in the solution were suggested as the main reasons for deviation from 1:1 PEC stoichiometry.