Template-Induced Precursor Formation in Heterogeneous Nucleation: Controlling Polymorph Selection and Nucleation Efficiency

Controlling crystallization: what liquid structure and dynamics reveal about crystal nucleation mechanisms

“…This result suggests that fluctuations of order in water layers in contact with an interface connote the polymorph that will be selected during freezing. Recently, we have performed an extensive study of crystal nucleation in nickel in the presence of small seeds, using TIS simulations [20]. The structural heterogeneity in the supercooled liquid was directly linked to the crystal nucleation mechanisms and the ability of the templates to enhance or decrease the nucleation probability.…”

“…But even for homogeneous systems and simple liquids, it is well known that crystallization pathways are often far from the classical scenario [2,[6][7][8][9][10][11][12][13][14]. For heterogeneous nucleation, other factors, such as template morphology, absorption and the local ordering of the contact liquid layer can impact nucleation mechanisms, and the classical scenario cannot be confirmed even for simple model interfaces [15][16][17][18][19][20].…”

“…Nevertheless, an imminent need of fundamental understanding of crystal nucleation processes is still essential in providing the relevant microscopic factors and physical-chemical descriptors that serve as inputs for training machine learning (ML) methods and meaningful screening of the nucleating ability of interfaces and materials. To this end, enhanced sampling simulations of nucleation processes [20,21] together with deep learning approaches are making it possible to access extended time scales and even use electron interactions to model crystallization in larger systems [22].…”

Ethylene Comonomer-Directed Epitaxial Nucleation and Growth of β-Nucleated Isotactic Polypropylene

“…6,7 This surface generally lowers the nucleation barrier by reducing interfacial free energy and thus modifies the nucleation kinetics and polymorph selection. 6,8 The subsequent crystal growth can be described as a homoepitaxial process, which involves the deposition of a succession of incoming polymer chains to the surface of an existing crystal plane, followed by a perfect crystallographic registry. 9 −11 The different polymorphs vary substantially by molecular conformations and/or packing arrangements in a unit cell.…”

“…Crystallization of polymers is described in terms of nucleation and growth, where the primary nuclei exceeding a critical size are formed by density and structure fluctuations, and the subsequent secondary nucleation and growth on the surface of existing nuclei govern the crystallization process. − Heterogeneous nucleation, as a predominant nucleation pathway, frequently initiates on a foreign surface. , This surface generally lowers the nucleation barrier by reducing interfacial free energy and thus modifies the nucleation kinetics and polymorph selection. , The subsequent crystal growth can be described as a homoepitaxial process, which involves the deposition of a succession of incoming polymer chains to the surface of an existing crystal plane, followed by a perfect crystallographic registry. − The different polymorphs vary substantially by molecular conformations and/or packing arrangements in a unit cell . Therefore, the structural features of growing crystal planes determine the growth rates of polymorphic forms …”