Chain Dynamics in a Polyelectrolyte Solution Under Shear: A Rheological NMR Investigation

Rheological nuclear magnetic resonance (NMR) has been applied to study the effect of shear on the chain dynamics in a solution of a linear poly(sodium 4-styrenesulfonate). Information on the chain dynamics of poly(sodium 4-styrenesulfonate) sheared in a narrow-gap concentric double cylinder cell is inferred from the NMR transverse relaxation T 2 for a concentration in the semidilute-entangled and in the concentrated regime. In the semidilute-entangled concentration enhanced relaxation is observed. In the concentrated regime signatures of a loss of entanglements are seen with increasing T 2 and a decreasing fraction of the polymer showing restricted motion. The effect is enhanced when the electrostatic interaction along the polymer chain is reduced by the addition of NaCl.