The effect of the molecular structure of an amphoteric copolymer, i.e., poly[acrylamide/(alpha-NN-dimethyl-N-(3-(beta-carboxylate)acrylamino)pro pyl)ammonium ethanate)] (PAD) on the interactions with BaTiO3 (BT) particles in water and on the stability of BT suspensions was examined by means of adsorption, potential, sedimentation, and viscosity measurements. The results indicate that the adsorption of PAD onto BT particles follows the Langmuir adsorption isotherm. As the added PAD containing greater ionic group fraction, both the saturated amount of adsorbed polymer and the amount of the polymer required to reach the minimal C potential decrease. Whatever the ionic group fraction in PAD, BT suspensions become stable and less viscous when saturated amount of the polymer was adsorbed on particle surface. (c) 2007 Wiley Periodicals, Inc.