The adsorption of sodium polyacrylate [NaPA] on noncarboxylated and carboxylated poly(n-butyl methacrylate-co-n-butyl acrylate) [P(BMA/BA)] latexes and ground calcium carbonate (GCC) was studied. The adsorption isotherms of NaPA on P(BMA/BA) latex surfaces showed that NaPA tended to adsorb to a greater extent onto the latex particle surfaces when the carboxyl group surface coverage of latex polymer particles is low, which indicates a repulsive interaction between the dissociated carboxyl groups and NaPA macroions. The electrophoretic mobility of cleaned model P(BMA/BA) latexes decreased with the increasing carboxyl group surface coverage at pH 10 due to the alkali-swelling characteristics of carboxylated latexes. For GCC, used as extender pigment particles in the pigmented latex blend systems, the size of the GCC pigment particles stabilized with NaPA decreased during a sonification process and their zeta-potential became increasingly negative with the addition of NaPA to the GCC pigment slurry. Particle size and zeta-potential measurements showed that NaPA can stabilize GCC particles effectively, and the optimum concentration of NaPA to stabilize GCC is around 1 wt % based on solid GCC. (c) 2005 Wiley Periodicals, lnc.