Study of processing adsorption mechanism of amphoteric polyelectrolyte in BaTiO₃ colloids suspension

An amphoteric dispersant, copolymer (α-N,N-dimethyl-N- acryloyloxyethyl) ammonium ethanateacrylamide (PAAM/DAAE), was used for the dispersion of BaTiO₃ (BT) colloids in an aqueous solution, and compared to a commercial acrylic-based polymeric dispersant, ammonium salt of polymethylacrylic acid (PMAA-NH₄). Several properties, including surface potential, sedimentation height ratio, green density, and Ba ²⁺ dissolution from the particle surface were studied. Due to the branch structure of PAAM/DAAE and more importantly the amphoteric functional groups of PAAM/DAAE, the macromolecules adsorbed on BT in much higher concentration (up to 7 mg/g) and limited the dissolution of Ba²⁺ ions from the BT surface. Strong steric repulsion between BT particles with PAAM/DAAE resulted in a good dispersion of fine particles and greater packing density in the green state than that of PMAA-NH₄. The adsorption mechanism and interactions among BT, dispersants, and H₂O are reported.