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Understanding polymer nucleation by studying droplets crystallization in immiscible polymer blends
Polymer ( IF 4.6 ) Pub Date : 2022-11-19 , DOI: 10.1016/j.polymer.2022.125514
Seif Eddine Fenni, Alejandro J. Müller, Dario Cavallo

This Feature Article reviews our recent work on the nucleation and crystallization of finely dispersed semicrystalline polymeric droplets in immiscible matrices. Droplets dispersions can be used as a toolbox to investigate polymer nucleation. Studying the overall crystallization kinetics of the droplets can be a way to separate the contributions of nucleation and growth rates depending on the sample. To characterize the relative importance of nucleation versus growth, we have defined a dimensionless parameter named the “Turnbull number”. This number equals the ratio of the time needed for a crystal to grow inside the average droplet volume, divided by the required time for nucleation to occur in the same droplet. We show examples for Turnbull numbers close to unity, where the overall crystallization kinetics of the droplets is dominated by crystal growth, and a sigmoidal (second or third order) kinetics is obtained. On the other hand, when the overall crystallization of the droplets is controlled by nucleation, very low Turnbull numbers are obtained (e.g., 0.1–0.01) with concomitant first-order kinetics. We also show how the nucleation step in the droplets can be skipped through the strategic use of self-nucleation. In the case of double crystalline polymer blends, the self-nucleation of the matrix can be used to study the surface nucleation of the droplets at the interface. The role of interfacial roughness in promoting droplet nucleation is also addressed, together with the addition of heterogeneous nucleating agents. Considering all the body of information, we demonstrate that studying the overall kinetics of different droplet dispersions can contribute to the fundamental understanding of polymer nucleation.



中文翻译:

通过研究不混溶聚合物共混物中的液滴结晶来了解聚合物成核

这篇专题文章回顾了我们最近在不混溶基质中精细分散的半结晶聚合物液滴的成核和结晶方面的工作。液滴分散体可用作研究聚合物成核的工具箱。研究液滴的整体结晶动力学可以是一种根据样品分离成核和生长速率贡献的方法。为了表征成核与生长的相对重要性,我们定义了一个名为“Turnbull 数”的无量纲参数。该数字等于晶体在平均液滴体积内生长所需的时间除以在同一液滴中发生成核所需的时间。我们展示了接近统一的 Turnbull 数的示例,其中液滴的整体结晶动力学受晶体生长支配,并获得 S 形(二阶或三阶)动力学。另一方面,当液滴的整体结晶由成核控制时,会获得非常低的特恩布尔数(例如,0.1–0.01)并伴随一级动力学。我们还展示了如何通过策略性地使用自成核来跳过液滴中的成核步骤。在双晶聚合物共混物的情况下,基体的自成核可用于研究液滴在界面处的表面成核。还讨论了界面粗糙度在促进液滴成核中的作用,以及异质成核剂的添加。考虑到所有的信息体,

更新日期:2022-11-19
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