Renkuan Cao, Hao Sun, Yunhan Zhang, Tingyu Xu, and Researcher Liangbin Li from our team published a research paper in Giant. Using self-seeding molecular dynamics simulations, this work investigated the microscopic mechanism by which flexible polymer chains transform into crystalline stems during polyethylene crystal growth.
The study revealed a wedge-shaped crystal growth front with a distinct interfacial layer approximately 0.95 nm in width. Outside this layer, polymer chain segments retained amorphous conformations. Upon entering the interfacial layer, van der Waals interactions from the crystal induced conformational transitions in the chain segments, leading to the formation of short initial stems. These initial stems subsequently underwent two successive stages of thickening, namely linear thickening followed by logarithmic thickening, eventually forming long crystalline stems. Both thickening stages proceeded through a slip mechanism: the linear stage was characterized by diffusion-controlled free slip, whereas the logarithmic stage involved confined slip governed by a slip barrier. This barrier was regulated by the interfacial packing density, which was, in turn, influenced by the conformations of the amorphous chains.
This study elucidates the microscopic mechanism underlying the transformation of flexible chains into crystalline stems during polyethylene crystal growth. By clarifying the intrinsic relationships among interfacial conformational transitions, stem thickening, and chain slipping, the findings provide new insights into the fundamental mechanisms of polymer crystallization.
This work was supported by a project of the Chinese Academy of Sciences (JZHKYPT-2021-04) and the National Natural Science Foundation of China (22503090).
Cao, R.; Sun, H.; Zhang, Y.; Xu, T.; Li, L. How flexible chain transforms into stem in crystal growth: Simulation insights from polyethylene. Giant 2026, 29, 100403.
Paper Link: https://doi.org/10.1016/j.giant.2026.100403
