Dispersion properties of BaTiO₃ colloids with amphoteric polyelectrolytes

An amphoteric water-soluble copolymer, i.e., poly(acrylamide/(α-N,N- dimethyl-N-acryloyloxyethyl) ammonium ethanate) (PAAM/DAAE), was evaluated as a novel dispersant for aqueous BaTiO₃ (BT) slurries. The dispersing property of this copolymer was examined by means of rheology, sedimentation, particle size, green density, zeta potential, and leached Ba²⁺ concentration measurements. The results indicate that PAAM/DAAE could reduce the viscosity of slurries greatly, cause BT particle sizes to shift to smaller values, and make green compacts more consolidated. Compared with a commercial dispersant, ammonium salt of poly(methacrylic acid) (PMAA-NH₄), it is as effective or even better in preparing stabilized suspensions. More importantly, PAAM/DAAE could lessen the leached Ba²⁺ concentration. This is related to the adsorption behavior of this copolymer onto BT particles, and the interaction between the adsorbed dispersant and dissolved barium ions.