THE EFFECT OF A SOLID WALL ON POLYMER-CHAIN BEHAVIOR UNDER SHEAR-FLOW

Molecular dynamics computer simulations are used to investigate the pr operties of isolated bead-rod chains with excluded volume effects unde r a simple shear flow. With the help of the collisional dynamics techn ique, the simulations are performed with both the chains end grafted t o an impenetrable wall and the isolated free-space chains immersed in a solvent. The comparison of these chains shows up the effect of the w all presence. We have calculated both the microscopic properties (such as end-to-end distance of polymer chain, the deformation ratio) and t he macroscopic rheological properties of the model polymer solution (s uch as shear viscosity, first normal stress difference). A comparative analysis of the chains dynamics shows that the response of the grafte d chains to simple shear flow is much different from that of the free chains. It was demonstrated that the grafting of polymer chains also g ives rise to the distinctive rheological properties of the polymer sol utions. For example, the effective viscosity of the grafted chains is an order of magnitude higher then the viscosity of the free chains. (C ) 1998 American Institute of Physics.