Growth Pathway and Precursor States in Single Lamellar Crystallization: MD Simulations

Large-scale and long-time molecular dynamics (MD) simulations are carried out to study the growth pathway of a single polymer crystal from an entangled dense melt via self-seeding. Using the concept of lifetime of individual stems, we can identify two stages of crystallization. The stem length increases linearly with its lifetime at the first stage (precursor stage) while it increases logarithmically at the following stage (thickening stage). Folds are created at the precursor stage, and refolding events are statistically irrelevant. This analysis concurs with the direct observation of a precursor zone around the growth front as defined by orientational order of segments. Precursor states can be identified as bundles of short stems which do not cover the growth front densely.