RHEOLOGY ENHANCEMENT BY MOLECULAR ASSOCIATION COMPLEXES.

Associations between polyethylene oxide polymer (PEO) chains and species containing sulfate groups can be used to increase the viscosity and elasticity of polymer solutions. The condensation of sodium dodecyl sulfate (SDS) micelles onto the PEO chain is shown to lead first to chain coil collapse and then to network or gel structure formation as SDS concentration is increased. Stronger interactions are produced between PEO and either Congo-red dye (a large organic molecule with two widely spaced sulfate groups) or polystyrene sulfonate (PSS). In these cases the association complexes lead to minor changes in the solution viscosity but large changes in the primary normal stress and storage modulus G prime at low frequencies.