The slow mode in semidilute neutral polymer solutions, dilute polyelectrolyte solutions and gels, is reviewed here. Our results suggest that the slow mode can be qualitatively considered as a hindered motion of interacting chains, even though the nature of interaction can be very different; namely, from the weak segment-segment interaction in a less good solvent to a strong electrostatic interaction among polyelectrolyte chains, and even to chemical crosslinking inside gel networks.
