Steady shear viscosity study of various HEUR models with different hydrophilic and hydrophobic sizes

The influence of the hydrophilic and hydrophobic sizes in hydrophobically modified ethoxylated urethanes (HEUR) was studied through the synthesis of two series of model thickeners. The model polymers were prepared by the step-growth (S-G) polymerization of polyethylene glycol (M. = 6000) with calculated amount of dicyclohexylmethane diisocyanate (H12MDI). The prepolymers molecular weights were adjusted by choosing the proper molar ratio of the reactants. For the first series, the isocyanate, end groups of prepolymers were reacted with cetyl alcohol, but in the second series, dodecyl alcohol was used. The synthesized models were characterized via molecular weight measurements and using an Ubbelohde capillary viscometer. The aqueous solutions of model HEUR were investigated by steady shear viscosity study. The model compounds showed excellent viscosity build up. It was found that the structural parameters have a very important effect on thickening efficiency, so that thickening efficiency increases with decreasing hydrophilic and increasing hydrophobic section sizes. (C) 2004 Elsevier B.V. All rights reserved.