Colloidal polyion complexation from sodium poly(acrylate) and poly(vinyl ammonium) chloride in aqueous solution

The colloidal polyion complex formed from sodium poly(acrylate) (NaPA) and poly(vinyl ammonium) chloride (PVACl) is almost stoichiometric but is slightly charged owing to the adsorption of an excess of the polyelectrolyte component onto the neutral complex. The charge stabilizes the colloidal polyacrylate-poly(vinyl ammonium) complex in an aqueous solution of a non-stoichiometric mixture of NaPA and PVACl, and the aggregation number of the colloidal complex increases as the stoichiometric composition is approached. This colloidal polyion complexation is an irreversible process, and the aggregation number depends on the method used to mix the NaPA and PVACl solutions. On the basis of the experimental results, we propose a simple model for colloidal polyion complex formation. Polymer Journal (2012) 44, 59-64; doi:10.1038/pj.2011.65; published online 3 August 2011