Structured Pigments Due to Polyelectrolyte Complex Formation, 1995 Coating Fundamentals Symposium Proceedings

Interactions between kaolin and cationic, i.E. Poly(ethyleneimine) and poly(diallyldimethylammonium chloride), as well as anionic polyelectrolytes, i.E. Poly(acrylic acid) were investigated with regard to the electrochemical stability of the resulting colloidal systems using electrophoretic light scattering. The kaolin dispersion can be anionically as well as cationically stabilized by adding the polyelectrolytes in excess. Such a pre-stabilized system can than be destabilized step by step via the addition of oppositely charged polyelectrolyte components. The tendency of flocculation is increased drastically by adding so called “symplex precursor” systems, i.E. Concentrated macroscopic homogeneous polyanion-polycation systems, which works like primary flocculants. In more practically relevant concentrated kaolin dispersions such symplex precursor systems are showing a behaviour like rheology modifiers. The drastic viscofying effect is broken down under moderate stresses.