We explore how the microscopic interactions link to bulk macroscopic properties of materials. We study systems of polymer chains in a solvent and examine the effect of hydrodynamic and of bonded and excluded volume interactions. First, we investigate how the entanglement of polymeric chains relates to bulk viscoelastic responses in polymeric materials. We show how the structure of the material can be analyzed using results from topology to develop new tools for entanglements. Next, we investigate the hydrodynamic effect of thermal fluctuations to the macroscopic properties of the material using the Stochastic Eulerian Lagrangian Method. Our studies will lead to a better understanding of the viscoelastic properties of materials which involve different length scales and complex microscopic interactions, like the cytoskeleton.