Concentration Dependent Dynamics of Semidilute Polymer Solutions: Universal Behaviour from Coarse-grained Simulations

In a wide variety of systems, knowledge of the behaviour of semidilute polymer solutions is of fundamental importance to obtaining predictive understanding. In this work, we use Brownian dynamics simulations to examine the concentration dependence of the dynamics of semidilute polymer solutions at equilibrium. Due to the overlap of polymer coils with increasing concentration, the properties of these solutions are highly nonlinear. In particular, intermolecular hydrodynamic and excluded volume interactions play a vital role in determining the solution dynamics. Using a fast implementation of the Ewald summation method we obtain predictions of the concentration dependence of static properties such as the radius of gyration, and of dynamic properties such as the long-time diffusivity. We find that the concentration dependence of these properties is universal, consistent with the predictions of scaling theories based on the blob model of polymer solutions. Keyword: Semidilute Polymer Solutions; Hydrodynamic interactions; Ewald summation; Brownian dynamics simulations.