Rheology of viscoelastic solutions of cationic surfactant. Effect of added associating polymer.

Rheological studies were performed with aqueous salt solutions of viscoelastic cationic surfactant erucyl bis(hydroxyethyl)methylammonium chloride (EHAC) and its mixtures with hydrophobically modified polyacrylamide. The solutions of surfactant itself above the concentration of crossover of wormlike micelles exhibit two regions of rheological response. In the first region, they behave like polymer solutions in semidilute regime characterized by viscoelastic behavior with a spectrum of relaxation times.

Molecular mass characterization of polymers with strongly interacting groups using gel permeation chromatography-light scattering detection.

This work is aimed at studying dilute solution behavior and developing techniques for the proper Mr characterization of polymers with strongly interacting groups. In particular, we have studied ionomers based on poly(dimethylcarbosiloxane) with carboxylic groups and hydrophobically modified polyacrylamide and its charged terpolymer. Gel permeation chromatography-light scattering (GPC-LS) study of organosilicon ionomers allowed us to follow molecular mass distribution evolutions during approximately a week that evidenced the gradual dissolution of clusters formed in bulk polymers.