Synthesis and Study of Branched Polyurethane Associative Thickeners for Water‐Borne Coating Materials

ABSTRACT A series of branched polyurethane thickeners was synthesized using isophorone diisocyanate, polyethylene glycol 4000, and cetyl alcohol, with dibutyltin dilaurate as catalyst and glycerol as branching agent. Polymers with different molar ratios of the components were prepared using both direct and inverse synthetic approaches. The synthesized structures were characterized by FTIR, 1 H NMR and 13 C NMR spectroscopy. Optimal hydrophobic/hydrophilic group ratios for maximum thickening effect were determined. Rheological properties of 15% aqueous thickener solutions were studied with the use of commercial acrylic dispersion. The study further examined how the synthesized thickeners affect such key technological parameters of water‐based acrylic dispersions as freeze–thaw resistance and dispersion stability.