Polymer Crystallization Kinetics

Abstract

Polymer crystallization, like many other phase transitions, occurs through a process of nucleation and growth. Although of fundamental importance, the nucleation step is still poorly understood, nevertheless, though major progress has been achieved in the past decade by using novel analytical tools. Herein, we outline the key experimental data and theories that have been developed to explain these data. A brief look at some more recent approaches is also given. The majority of this article considers the growth process itself, concentrating on linear, flexible polymers as this is the area where the most complete data set is available. An outline of the theories that have been developed to explain and predict crystallization kinetics is also given, focusing on their fundamental assumptions and predictions rather than their mathematical intricacies. This article is not intended to be an all‐inclusive review on the topic but rather a tutorial style introduction. For the sake of brevity, this article will, therefore, concentrate on areas that are of particular interest to the authors and to principles and observations that have, in the authors’ opinion, the widest applicability.

Backbone flexibility on conjugated polymer's crystallization behavior and thin film mechanical stability

“…Androsch and Schick reviewed the possible reasons contribute to such bimodal dependence and suggested that as supercooling increases, the significant increase in the nucleation density, accompanied with a change in nucleation mechanism (homogeneous nucleation at high supercooling vs. heterogeneous nucleation at low supercooling), frequently lead to different crystal polymorphs with the mesophase being metastable at high supercooling. [51][52][53] Those factors are presumably the cause for the bimodal dependence of the crystallization rate for PNDI-C3, evidenced by the presence of multiple melting peaks and melting-reorganization process in the subsequent heating scans (Figure 2F). At low supercooling, the formed crystals mainly melt at a peak T m of approximately 104.3 C with a small shoulder-melting peak at lower temperature.…”