Topological constraints govern the dynamics of entangled macromolecules when polymers exceed a critical molecular weight. The crossover from the low molecular limit described by the Rouse model to dynamics prescribed by entanglements has been the subject of extensive research with significant challenges present. Constraint release and contour length fluctuations are often introduced into phenomenological descriptions to capture dynamics that depart from the original Doi-Edwards tube theory. Polyisoprene melts have long served as a prototype experimental system to study the evolution of the end-to-end distance along with mechanical relaxation. We present results on dynamics probed over 12 orders of magnitude in time using a combination of atomistic and bottom-up parameterized coarse-grained and slip-spring simulations. Generated data are contrasted to dielectric relaxation spectroscopy experiments and rheological measurements in the literature with a good agreement found, particularly for highly entangled polymer melts. Our study supports the ability of the scheme to provide bottom-up parameter-free predictions on the dynamics of polymeric materials. In addition, we systematically examine the application of theoretical models to our strictly monodisperse <i>cis</i>-1,4 polyisoprene melts and provide estimates of the phenomenological parameters employed. Finally, we discuss extensions of our study that enable us to address systematically, dynamics of copolymers in the melt and in proximity to solid surfaces.

Dynamics of long entangled polyisoprene melts via multiscale modeling

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