Viscoelasticity of dilute polymer solutions.

The current understanding of viscoelastic phenomena in dilute solutions of polymers is reviewed. The simple theory of Rouse must be corrected for the effects of hydrodynamic interaction, excluded volume, finite extensibility, and internal viscosity. Hydrodynamic interaction is the indirect drag, transmitted through the solvent, that one part of the polymer chain exerts on another. Excluded volume is the effective repulsive force that one part of the polymer chain feels for another in good solvents. When coils are highly stretched, their dynamics are influenced by their finite extensibility, which produces a nonlinear relationship between the elastic force and molecular extension. Internal viscosity is a resistance to chain stretching; it is strongest in stiff or rigid macromolecules. Hydrodynamic interaction shortens the longest Rouse relaxation times and thereby compresses the relaxation spectrum.