Multiscale Modeling of Polydisperse Entangled Polymer Melts Under Equilibrium and Flow

Polydispersity influences the dynamics of polymer melts, yet its effects are challenging to capture across the wide range of relevant time and length scales. Here, we develop a multiscale modeling framework that integrates atomistic, coarse-grained, and slip-spring simulations to investigate how molecular weight distribution governs the dynamics and rheology of entangled polymer melts under both equilibrium and non-equilibrium (simple shear) conditions. Using atactic polystyrene as a model system, we validate our hierarchy of models against atomistic simulations and experimental data, demonstrating accurate predictions of chain entanglement, relaxation spectra, and flow response. This bottom-up framework bridges molecular-scale chemical-specific interactions with macroscopic observables, providing quantitative insights into viscoelastic behavior in realistic polydisperse systems relevant to circular polymer design, reprocessing, and sustainable polymer formulations.