Crystallization of Polymer Melts: Effects of Model parameterization and Molecular Weight on Low-Temperature Phases

Hundreds of millions of tons of semi-crystalline polymers are produced annually, yet the molecular mechanisms of polymer crystallization remain incompletely understood. A key open question concerns how low-temperature phase behavior influences the primary nucleation process. In our recent work, we have used advanced sampling Monte Carlo methods including Wang-Landau (WL) and Expanded Ensemble Density of States (EXEDOS) simulations to compute phase diagrams and free energy landscapes (FELs) relevant to crystallization from the melt. Our previous findings indicate that nucleation is highly sensitive to chain flexibility, but relatively insensitive to other molecular parameters. Building on this, we have extended our simulations to explore larger systems, including those with longer molecular weights. We will discuss the methods used to reach larger systems, finite-size effects, the impact of molecular weight, and the implications of these new results on the potential for multistep nucleation processes and "universality classes" of polymer crystallization.