Simple crystallizable bead-spring polymer model

TL;DR

This paper introduces a simple, computationally efficient coarse-grained bead-spring polymer model that captures competing crystallization and glass transitions, useful for studying generic semicrystalline polymer features.

Contribution

The authors develop a new coarse-grained polymer model that balances simplicity and realism, enabling efficient simulation of crystallization and glass transition phenomena.

Findings

Crystallization occurs below a critical temperature with FCC/HCP order.

Amorphous regions grow with increasing quench rate, leading to nearly amorphous structures.

Model reproduces key features of polymer crystallization with computational efficiency.

Abstract

We develop a simple coarse-grained bead-spring polymer model exhibiting competing crystallization and glass transitions. For quench rates slower than the critical nucleation rate $|\dot{T}|_{crit}$, systems exhibit a first-order crystallization transition below a critical temperature $T=T_{cryst}$. Such systems form close-packed crystallites of FCC and/or HCP order, separated by domain walls, twin defects, and an amorphous interphase. The size of amorphous regions grows continuously as the quench rate $|\dot{T}|$ increases, producing nearly amorphous structure for $|\dot{T}|>|\dot{T}|_{crit}$. Our model exhibits many features observed in recent studies of crystallization of athermal polymer packings, but also critical differences arising from the softness of the pair interactions and the thermal nature of the phase transition. The model is considerably more computationally efficient than other recent crystallizable coarse-grained polymer models; while it sacrifices some features of real semicrystalline polymers (such as lamellar structure and chain disentanglement), we anticipate that it will serve as a useful model for studying generic features related to semicrystalline order in polymer solids.