Design of polymeric dispersants for waterborne coatings

Block and random copolymers of ammonium methacrylate and dimeth-ylaminoethyl methacrylate have been synthesized and tested as dispersants of various organic and inorganic pigments in formulations for waterborne paints. Blockiness of the co-monomer distribution is a prerequisite for good color characteristics in the final paint. It is however noteworthy that a tapered diblock (one-step anionic synthesis), a diblock copolymer with a regular change in composition from one block to the other one, has an interfacial activity quite comparable to the parent “pure” diblock copolymer (two-step anionic synthesis). The most interesting observation is that the poly(dimethylaminoethyl methacrylate) anchoring block can impart stability to dispersions of pigments as different as iron oxide, a blue Cu-phthalocyanine pigment, and a red organic pigment based on pyrrole in representative aqueous paint formulations. This type of diblock copolymer is promising for the design of universal dispersants. Center for Education and Research on Macromolecules (CERM), Sart-Tilman, B6, 4000 Liège, Belgium. Rijksstraatweg 31, P.O.Box 3, 2170 BA Sassenheim, The Netherlands.