Property Decoupling across the Embryonic Nucleus-Melt Interface during Polymer Crystal Nucleation

Area of Science:

• Polymer Science
• Materials Science
• Physical Chemistry

Background:

• Understanding polymer crystallization is crucial for material properties.
• Early-stage nucleation dynamics influence macroscopic semicrystalline structures.

Purpose of the Study:

• To quantitatively map polymer property variations around nascent polymer crystals (nuclei).
• To investigate the influence of nuclei on surrounding polymer melt ordering.
• To explore the emergence of crystal stacking during early nucleation stages.

Main Methods:

• Spatial distribution analysis of polymer properties (segment alignment, density, potential energy) relative to nuclei.
• Characterization of nuclei and interface extents.
• Identification of ordered polymer segments beyond the nucleus.

Main Results:

• Polymer nuclei exhibit metric-dependent spatial extents and solid-like interiors.
• Density rapidly decays to melt-like behavior, while segment alignment persists, forming a nematic-like droplet.
• Enhanced ordering of non-constituent polymer segments near nuclei suggests induced nucleation.
• A second region of ordering along the nematic director indicates early crystal stacking.

Conclusions:

• Crystal stacking initiates during the earliest stages of polymer crystallization (nucleation).
• Polymer nuclei create ordered environments that influence surrounding melt and potentially induce further nucleation.
• Findings bridge nucleation under non-flow and flow conditions, explaining previous observations.