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Effect Of Ionic Strength On The Rheological Properties Of Multisticker Associative Polyelectrolytes
Published 2006 · Chemistry
The rheology of hydrophobically modified polyelectrolytes containing small hydrophobic blocks randomly distributed along the hydrophilic backbone has been investigated in aqueous salt solutions by means of steady-flow, creep, and oscillatory experiments. The polymers contain acrylamide (≈86 mol %), sodium 2-acrylamido-2-methyl-1-propanesulfonate (≈12 mol %), and N,N-dihexylacrylamide units (≈2 mol %). The rheological behavior in the presence of electrolyte for two polymers with two different hydrophobic block lengths (NH = 3 or 7 monomer units per block) was compared to that obtained for salt-free systems. At a fixed salt concentration, the critical concentration at the onset of viscosity enhancement does not depend on the length of the hydrophobic segments in the polymers and is located in the vicinity of the critical overlap concentration of the corresponding hydrophobe-free polymer. This is in strong contrast to the behavior observed for the same polymers in pure water, for which the onset of viscosity...