ASSOCIATIVE THICKENERS .1. SYNTHESIS, RHEOLOGY AND AGGREGATION BEHAVIOR

Nonionic associative thickeners with systematic changes in chemical composition have been synthesized. Rheological measurements of thickened latexes are presented as well as measurements of relaxation times, intrinsic viscosity and osmotic pressure of polymers in pure water solution. We find that the general hydrophobicity of the polymers' end groups control both rheology and efficiency. Hydrophobic parts in the interior of the polymer do not seem to effect rheology in latex systems. Viscosity increases with molecular weight in the low molecular region (Mw < 10000), and passes through a maximum in the high molecular region. The thickeners seem to form micelle-like aggregates even at very low concentrations, while at higher concentrations the viscoelastic properties may be modeled by means of one Maxwell element. Only the network relaxation times but not the network structure seems to be dependent on the polymers' end group.