Unifying Model for Associative Thickener Influences on Water Borne Coatings II – Competitive Adsorption of Nonionic Surfactants and HEUR Thickeners on Titanium Dioxide Pretreated with Inorganic Stabilizers and Organic Oligomeric Dispersants

By Ming-Ren Tarng, Mao Chen , J. Edward Glass, John G. Dickinson

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 Ti02 surfaces. The isoelectric point imposed on Ti02 by the metal oxide surface treat­ment determines the amount of organic dispersant adsorbed,

The size of the a-olefin on the maleic acid dispersant is also important in the adsorption of the dispersant. The size of the a-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 hydro­phobe size of the HEUR is discussed.