Hydrophobically end-capped poly (ethylene oxide) urethanes. Part 3: Effect of sodium dodecyl sulphate on their association in aqueous solution

Abstract

The interactions between sodium dodecyl sulphate (SDS) and three autoassociative polymers (hydrophobically end-capped poly(ethylene oxide) urethanes) are studied by conductimetry, fluorescence, and viscometry. By the first two techniques the interactions are found to increase with the hydrophobicity of the polymer and to be stronger than those observed for a polyethylene oxide (PEO) of the same order of molecular weight. The results seem to be consistent with a model where SDS micelles are formed around hydrophobic chain ends in a first stage, and along the main chain in a second stage. For the more hydrophobic sample already self-aggregated in water and of relatively large reduced viscosity, the addition of SDS induces a loss in viscosity contrary to the less hydrophobic ones and PEO. Such effect may be attributed to the destruction of the chain end association by the formation of SDS micelles around one end in the first stage of the interaction.