Reevaluation of the Crystallization Kinetics of Precisely Synthesized, Discrete Oligo(γ-butyrolactone)s

Abstract

The crystallization behavior of polymers has always been an important part of polymer physics. The data from a previous paper, “Crystallization Kinetics of Precisely Synthesized Discrete Oligo(γ-butyrolactone)s” published in Acta Polymerica Sinica (2022), are further discussed here in order to clarify some issues which could easily be confused. We show here that the crystallization process was affected not only by the molecular weight, but also by the end group. In the case of oligo(γ-butyrolactone)s, the crystallization rate was restrained by the end group, t-butyl diphenyl silicon, within the oligomer chain due to its different structure from the repeat unit and its steric effect. As the content of the end groups was relatively high for the lower molecular weight, the crystallization was inhibited. With the increasing molecular weight, the influence of the end groups decreased. Since the content of the end group t-butyl diphenyl silicon was below 10 wt%, the crystallization rate with higher molecular weight was slower than that with lower molecular weight, similar to the general rule. In the case of polydisperse oligomers with relatively high molecular weight, the components with not too low molecular weight which crystallization would not be affected by the terminal groups, such as the components with 32 structural units, would make a greater contribution to the crystallization process resulting in faster crystallization rate, rather than those with higher molecular weight than the average molecular weight.