An associative polyelectrolyte end-capped with short polystyrene chains. Synthesis and rheological behavior

Polystyrene(PS) end-capped polyelectrolytes were prepared by modification of polystyrene-poly(tert-butyl acrylate)-polystyrene triblock copolymers synthesized via anionic polymerization. These amphiphilic polymers are associated in dilute aqueous solutions forming loose multimicellar clusters. At higher polymer concentrations an extensive intermicellar bridging occurs, leading to the formation of a transient network as revealed by the viscoelastic response of the system. The so-formed gel is characterized by low gel concentration, i.e., 0.2 wt %, yield stress, complex steady-shear viscosity profile, high plateau modules, and long relaxation times. These characteristics can be attributed to the highly hydrophobic character of the PS junctions and the stretched conformation of the polyelectrolyte bridges.