Some zinc dicarboxylic acids can induce numerous β-crystals formation in isotactic polypropylene (iPP), thus improving the crystallization behavior and mechanical properties of iPP. However, the corresponding nucleation mechanism of β-crystals remains inadequate, leading to the absence of a theoretical basis for the design and preparation of new and high-efficiency β-nucleating agents (β-NAs). In this work, we demonstrate a new mechanism that β-crystals can be formed when the interfacial interaction between β-NAs and iPP is comparable to that between β-PP and iPP. The interfacial interaction occurs when iPP epitaxially crystallizes on the NA surface, which will affect the folding and arrangement of iPP chains, thereby leading to formation of different crystalline forms of iPP. The interaction energy of iPP chain with α-PP and β-PP is used as a judgment criterion, which is resolved by molecular dynamics (MD) simulation. We surprisingly found that when the interaction energy of NA/iPP was close to that of β-PP/iPP, the NA can be acted as β-NA; β-crystals were inclined to form when the interaction energy of NA/iPP was close to that of β-PP/iPP. Furthermore, the simulation results are well verified by the crystallization behavior of iPP in the presence of aromatic zinc dicarboxylic acids of zinc terephthalate (ZnCC1) and zinc 4-carboxybenzoate (ZnCC2), lending strong support to the proposed nucleation mechanism and method. This work proposes a new insight into the formation of β-crystals of iPP based on the interaction energy of NA and iPP, and demonstrates a method to rapidly predict and evaluate the β-nucleation effect of NAs, thus may serve as a theoretical guidance for the design of NAs that can induce iPP with specific crystalline forms.

一些二羧酸锌可以在全同立构聚丙烯 (iPP) 中诱导大量 β 晶体形成，从而改善 iPP 的结晶行为和机械性能。然而，β-晶体的相应成核机制仍然不足，导致缺乏设计和制备新型高效β-成核剂（β-NAs）的理论基础。在这项工作中，我们证明了当 β-NAs 和 iPP 之间的界面相互作用与 β-PP 和 iPP 之间的界面相互作用相当时可以形成 β-晶体的新机制。当iPP在NA表面外延结晶时发生界面相互作用，这将影响iPP链的折叠和排列，从而导致形成不同晶型的iPP。iPP链与α-PP和β-PP的相互作用能作为判断标准，通过分子动力学（MD）模拟解决。我们惊奇地发现，当NA/iPP的相互作用能接近β-PP/iPP时，NA可以充当β-NA；当NA/iPP的相互作用能接近β-PP/iPP的相互作用能时，倾向于形成β-晶体。此外，iPP 在对苯二甲酸锌 (ZnCC1) 和 4-羧基苯甲酸锌 (ZnCC2) 的芳族二羧酸锌存在下的结晶行为很好地验证了模拟结果，为所提出的成核机制和方法提供了强有力的支持。这项工作提出了基于 NA 和 iPP 的相互作用能形成 iPP β 晶体的新见解，