J. Kotz et S. Kosmella, INTERACTIONS BETWEEN POLYANION-POLYCATION SYSTEMS AND KAOLIN, Journal of colloid and interface science, 168(2), 1994, pp. 505-513
The phase behavior of the polyanion-polycation system, consisting of a
branched polyethylene imine and a sodium salt of polyacrylic acid, wa
s investigated as a function of the polymer concentration. At low poly
mer concentrations a small area of initial phase separation was observ
ed, surrounded by a homogeneous one-phase system. The homogeneous, con
centrated polyanion-polycation systems were characterized viscometrica
lly, densitometrically, and spectroscopically. Under special mixing co
nditions, a significant viscosity enhancement was observed due to Coul
ombic interactions between the oppositely charged polyelectrolyte comp
onents. The interactions of the polyelectrolyte components with kaolin
were investigated separately in the concentration range of initial ph
ase separation as well as in the area of concentrated, optically clear
polyanionpolycation systems. In the concentration range of phase sepa
ration polyanion-polycation interactions are dominant with regard to p
olyelectrolyte-kaolin interactions. When adding concentrated homogeneo
us polyanion-polycation systems to concentrated kaolin dispersions abo
ve a critical polyelectrolyte concentration, a transition to polyelect
rolyte-kaolin pastes was observed. In general, these results are of pr
actical importance for a better understanding of structuring phenomena
in pigment systems. (C) 1994 Academic Press, Inc.