Rheologica Acta, Vol.33, No.6, 485-505, 1994
A TERMINALLY ANCHORED POLYMER-CHAIN IN SHEAR-FLOW - SELF-CONSISTENT VELOCITY AND SEGMENT DENSITY PROFILES
The behavior of a terminally anchored freely-jointed bead-rod chain, subjected to solvent shear flow, was investigated via Brownian dynamics simulations. Previous calculations have been improved by computing the segment density and fluid velocity profiles self-consistently. The segment density distributions, components of the radius of gyration, and chain attachment shear and normal stresses were found to be sensitive to low values of shear rate. Additionally, it was found that the thickness of a model polymer layer was a strong function of the shear rate, and that the functional dependence on shear rate changed dramatically as the chain length increased. For the longest chains studied, the thickness of the model polymer layer first increased as the shear rate increased, passed through a maximum, and then decreased at high shear rates, in accordance with experimental results in theta solvents. These results suggest that a dilute or semi-dilute layer model may explain hydrodynamic behavior previously thought to be due to the entanglements that occur in dense surface bound polymer layers.
Keywords:ADSORBED POLYMER;MONTE-CARLO;HYDRODYNAMIC THICKNESS;KINETIC-THEORY;DYNAMICS;MODEL;INTERFACE;MACROMOLECULES;CONFORMATION;ADSORPTION