Thickening of butyl acrylate/styrene/2-hydroxyethyl methacrylate/acrylic acid latices with an HEUR associative thickener

Thickening of acrylate copolymer latices containing various amount of 2-hyd roxyethyl methacrylate (HEMA) by commercial associative thickener SER-AD FX 1070 (CONDEA Servo BV), based on hydrophobic ethoxylated urethane (HEUR), showed that the thickening efficiency decreases with the HEMA content in th e latex copolymer. The strongest increase in viscosity occurred in the late x without HEMA comonomer suggesting formation of the network space structur e due to the bridging of the latex particles by adsorption of hydrophobic e nds of the thickener. When HEMA was incorporated into the latex copolymers, the particle surface became more hydrophilic and the association of the th ickener was more significant. In this case thickening was much lower and wa s only a result of the hydrodynamic interaction between swollen latex parti cles and the thickener macromolecules or their aggregates (clusters, micell es). (C) 2001 Elsevier Science B.V. All rights reserved.