BROWNIAN DYNAMICS OF CONCENTRATED POLYMERS IN 2 DIMENSIONS

Two-dimensional simulations of the Brownian dynamics of polymers in a grid of topological obstacles were carried out in this study. A first model made use of the exact expression for the free energy of a chain with fixed ends interacting with an obstacle and can be used to derive the elastic force acting on the subchains of a Rouse-like model. With this model we calculated the diffusion coefficient of chains of diffe rent lengths constrained by the fixed obstacles. A second model, less rigorous but more efficient computationally, was used to simulate the chain dynamics in fast flows. In such a case, the obstacles were conve cted according to the shear gradient. During the simulation, the confi gurational changes of the chain constrained by the obstacles could be monitored and the stresses which developed were calculated. These simu lations reveal important effects of the conformational fluctuations at high shear rates. (C) 1998 Elsevier Science B.V. All rights reserved.