The specific interactions between HEUR associative polymers and surfactants

Abstract

The influence of the surfactant structure on the thickening mechanism of low molecular weight thickeners is examined. Experimental results from rheological experiments are evaluated. The surfactants used are Akyposal BA56, Akyposal RLM56, Akyposoft 100 NV, Surfagene S 30, Akypo RLM25, Avanel S90 and Avanel S30. The thickening mechanism in concentrated surfactant systems of low molecular weight thickeners is based on the increase of the hydrodynamic volume of the micelles by the building of EO-shells around the micellar core. The presence of long EO-chains in the surfactant molecules makes it impossible to build the additional shells. The ionic headgroup present in the surfactant molecule can, to some extent, either reinforce of diminish this effect. Sulphate surfactants have a stronger specific interaction with the EO-groups of the rheology modifier than sulphonates, and these are again stronger than carboxylic acid salts.