Synthesis and rheological behavior of poly[acrylamide–acrylic acid–N-(4-butyl)phenylacrylamide] hydrophobically modified polyelectrolytes

Hydrophobically modified polyelectrolytes were prepared by an aqueous micellar copolymerization technique from acrylamide, N-(4-butyl)phenylacrylamide, and a third monomer, sodium acrylate. The amounts of surfactant and anionic monomers used in the synthesis have great effects on the molecular structures and the association behaviors of the resultant polymers. Rheological properties have been studied as a function of polymer concentration, ionic strength, temperature, shear rate, viscoelasticity, and so on. As expected, the copolymers exhibit improved thickening properties owing to the strong synergistic viscosification effects of the ions and the hydrophobic groups of the polymer molecules. Atomic force microscope studies were used to explore the aggregation morphology and association mechanism of such polymers.