Effects of Concentration on Steady-State Viscometric Properties of Short Chain Polymer Solutions Over the Entire Concentration Range

Relationships between viscometric behavior and concentration are observed and evaluated through a series of nonequilibrium molecular dynamics simulations of the behavior of 20-site polymers in solution with explicit solvent across the full concentration range. The zero-shear viscosities, first normal stress coefficients and steady-state shear compliance of the solutions are examined alongside conformational properties including the excluded volume effect. The variation of viscosity with concentration in these solutions is described by the Huggins equation up to relatively high concentrations. At these high concentrations, the effects on conformation of excluded volume iInteractions decline, while no clear semi-dilute region is identifiable. Although the steady-state shear compliance of the system appears concentration-independent, the dilute and melt behaviors of this system are accurately described by the theories of Zimm and Rouse, respectively.