Selectivity of Hydrophilic and Hydrophobic TiO2 for Organic-Based Dispersants

The effects of the surface chemistry of TiO2 powders on the dispersion performance of various dispersants are studied. Four common dispersants (oleic acid, oleylamine, oleyl phosphate, and tris-(2-butoxyethyl) phosphate) with different functional groups (carboxyl (-COOH), amino (-NH2), phosphate (-P(=O)(OH)(2)), and -P(=O)) are investigated for their potential to disperse hydrophilic and hydrophobic titania (TiO2) powders. The outcomes, based on adsorption kinetics, adsorption isotherms, rheologies, and theoretical calculations, indicate that the hydrophilic TiO2 is more sensitive to the chemistry of dispersants as compared to the hydrophobic TiO2. However, the relative dispersion efficiencies of the dispersants are not found relevant to the adsorption kinetics, which is dominated by the adsorption amount. In addition, hydrogen bonding between -OH groups of the phosphate-based dispersants dominates their dispersion ability for TiO2.