Unifying model for associative thickener influences on waterborne coatings: II. Competitive adsorption of nonionic surfactants and HEUR thickeners on titanium dioxide pretreated with inorganic stabilizers and organic oligomeric dispersants

Size exclusion chromatography in tandem with UV absorbance of the surfactant is used to separate and quantify the amount of nonionic surfactant and model hydrophobically modified ethoxylated urethane (HEUR) thickeners adsorbed on different organic oligomeric polyacid, metal oxide-treated TiO2 surfaces. The isoelectric point imposed on TiO2 by the metal oxide surface treatment determines the amount of organic dispersant adsorbed. The size of the alpha-olefin on the maleic acid dispersant is also important in the adsorption of the dispersant. The size of the alpha-olefin on the organic acid dispersant, in turn, determines the amount of surfactant and HEUR thickener adsorbed. The surfactant, unlike the HEUR thickener, exhibits a dependence on the metal oxide treatment in neutral media, independent in several aspects of the amount of organic dispersant adsorbed. The adsorption dependence of HEUR thickeners and nonionic surfactant on the hydro-phobe size of the HEUR is discussed.