Secondary nucleation in polymer crystallization: A kinetic view

Abstract

Secondary nucleation on the surfaces of growing crystals plays a vital role in polymer crystallization, which determines the lamellar thickness at growth front and the radial growth rate. Though secondary nucleation has been intensively studied in the past decades, our understanding on the molecular mechanism and kinetics is not yet complete. In this perspective, we will briefly review the major advances in the secondary nucleation of flexible polymer chains in the past decade and discuss some remained questions from a viewpoint of kinetics. The main theories, thermodynamics and kinetics of secondary nucleation are first summarized. The difference of nucleation of polymer chains from that of small molecular crystals is revealed via analysis of kinetics. Then, the interplay of various microscopic processes leading to the final crystalline structures is discussed, such as lamellar thickening versus widening, intra‐chain vs inter‐chain nucleation, secondary nucleation versus lateral spreading, secondary vs primary nucleation, nucleation of polymorphisms, and so forth. Finally, some remained open questions are highlighted. Combining kinetic theory considering various microscopic processes and new experimental evidences at different length and time scales would greatly help deepen our understanding on the secondary nucleation during crystallization of flexible polymer chains.

Non-Isothermal Crystallization of Titanium-Dioxide-Incorporated Rice Straw Fiber/Poly(butylene succinate) Biocomposites

“…There are two different crystallization mechanisms with varying activation energies that affect the activation energies at a certain relative degree of crystallinity. The total crystallization rate can be regulated by the nucleation and transport of macromolecules in the melt stage, according to the secondary nucleation theory proposed by Hoffman and Lauritzen [ 57 ]. Rice straw fibers act as nuclei for the heterogeneous nucleation of polymer chains to enhance the crystallization of PBS in the RS/PBS composites.…”

From Chaos to Ordering: New Studies in the Shannon Entropy of 2D Patterns

“…In the realm of polymer crystallization, the introduced process corresponds to the “secondary nucleation” scenario introduced by Lauritzen and Hoffman in their pioneering paper on the theory of polymer crystallization from dilute solution, published in 1960 [ 38 ]. Secondary is the nucleation which occurs on the surfaces of crystals of the material [ 38 , 39 ]. Thus, new seeds appearing on the edges of the Voronoi tessellation are seen as the centers of the secondary crystallization [ 39 ].…”

“…Secondary is the nucleation which occurs on the surfaces of crystals of the material [ 38 , 39 ]. Thus, new seeds appearing on the edges of the Voronoi tessellation are seen as the centers of the secondary crystallization [ 39 ]. Secondary crystallization in polymer results in formation of lamellae constituting polymer spherulites, as shown in references [ 38 , 39 ].…”

“…Thus, new seeds appearing on the edges of the Voronoi tessellation are seen as the centers of the secondary crystallization [ 39 ]. Secondary crystallization in polymer results in formation of lamellae constituting polymer spherulites, as shown in references [ 38 , 39 ]. The consequent iterations of the introduced procedure of generation of Voronoi diagrams correspond to the stages of secondary, tertiary, etc., crystallization occurring in the polymer melt or solution.…”

“…These conclusions support the findings established under the analysis of the Penrose tiling and ordering registered for the levitating water clusters [ 28 , 29 ]. It is reasonable to suggest that the introduced mathematical iterative procedure possesses substantial common features with the secondary crystallization process, giving rise to the formation of spherulites in the polymer melts and solutions [ 38 , 39 ].…”