Anionic polyurethane ionomers as the dispersant in water-soluble acrylic baked paint were successfully synthesized at our lab and these ionomer structures have been proven by infrared spectra. In aqueous solution, the surface tension for polyurethane ionomer molecules with different ionics was found to increase with increasing the concentration of ionics, as a result of the hydrophobics of ionomer molecules adsorbed at the air-water interface becoming even more ordered. It was also found that the viscosity, is higher for polyurethane ionomer with (L)-2,5-diaminovaleric acid hydrochloride than for polyurethane ionomer with sodium 4,4-dihydroxy-1-butane sulfonate (DS200) or with dimethylol propionic acid (DMPA) in water. For the wettability and dispersion of titanium dioxide pigment present in water-soluble acrylic baked paint, the polyurethane ionomer molecules with respective sodium 4,4-dihydroxy-(L)-butane sulfonate, DMPA, DS200 containing 3%. 1,3propane sultone (ES200) and DMPA containing 3% ES200 are considered to be better dispersants. The titanium dioxide pigment was found to become finer, as the agitation time and the ionic concentration of anionic polyurethane ionomer were increased. In addition, the system with DS200 or dimethylol propionic acid will make the dispersion of titanium dioxide pigment stable in water-soluble acrylic paint. (C) 2005 Wiley Periodicals, Inc.