Using Molecular Dynamics Simulations to Understand Entangled Polymeric Liquids

The dynamics of chains in entangled polymeric liquids and its relationship to the macroscopic rheological properties is of both fundamental and industrial interest. One approach that has proven quite illuminating is to investigate the motion of relatively simple, bead-spring type, polymer model chains simulated on a computer using the molecular dynamics technique. In order to highlight the power and the potential of molecular dynamics simulations, I will provide two illustrations of the use of molecular dynamics to elucidate aspects of entangled polymer liquids. The first will deal with the relationship between the structure of a polymer melt and a physical property that is determined by the topological constraints experienced by a chain in the melt, the plateau modulus. The second will deal with the use of molecular dynamics to obtain adequately detailed information to perform a rigorous test of the ability of a single chain model to describe the dynamics and rheology of entangled polymer liquids in the linear regime.