A uniform understanding of polymer crystallization models: Diffusion and conformational transition model.

In the last 100 years, the study of polymer crystallization theory has achieved many breakthroughs, and a large number of models and theories have been proposed. However, each of them can only partially explain the crystallization behavior of polymers. A uniform understanding of polymer crystallization remains a huge challenge. In this paper, we try to understand the crystallization of polymers from the motion of polymer chains, and a universal model, the diffusion and conformational transition (DCT) model, is proposed. The DCT model can provide a unified understanding of the current polymer crystallization models. We propose that the nature of polymer crystallization is the synergy and competition between the diffusion (D) and the conformational transition (CT) processes. Moreover, by dividing the types of D and CT into D 1 to D 3 and CT 1 to CT 6 , respectively, the homogeneous nucleation process and the growth of polymer crystals on the surface of an existing crystal are discussed. Some important results on the number of stems for critical nuclei, the type of nucleation, the origin of the conformation of chain segments on the end surface of lamellar crystals, etc. have been achieved. These results not only provide a good explanation of the experimental findings in the literature, but also contain some new findings. The DCT model may further be used to resolve disputes, explain and predict new phenomena, and teach beginners in polymer crystallization in the future. [Display omitted] • A universal polymer crystallization model is proposed. • The nature of polymer crystallization is the synergy and competition between the D and the CT processes. • Intermolecular nucleation is easier for small nuclei and intramolecular nucleation is easier for larger nuclei. • The number of stems for critical primary and secondary nuclei is independent of the type of nuclei. • The competition between CT 4 /CT 5 and D 3 results in tightly folded-chains, loops, cilia, and tie chains. [ABSTRACT FROM AUTHOR]