Kinetics of crystal nucleation of polymers and low-molecular-weight organic compounds: Using Tammann’s approach to discover differences and similarities

聚合物和低分子量有机化合物的晶体成核动力学：使用塔曼方法发现异同

• 批准号: 464908856
• 负责人: Professor Dr.-Ing. René Androsch
• 金额: --
• 依托单位: Interdisziplinäres Zentrum für Transferorientierte Forschung in den Naturwissenschaften (IWE TFN)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/464908856?language=en
• 关键词: Kinetics; crystal; nucleation; polymers; low

The properties of crystallizable materials greatly depend on the fraction, morphology, and higher-order organization of crystals. Crystal growth is preceded by nucleation, with the nuclei number affecting these parameters. Controlling nucleation is a key tool to tailor structure formation and material performance. While crystal growth and heterogeneous nucleation are well studied, homogeneous nucleation is understood much less, mainly due to lack of analysis tools.Nucleation at high melt-supercooling can be studied employing Tammann’s two-stage nuclei development method, well-established for slow crystallizers, e.g. ceramics. This approach implies nuclei formation at low temperature where growth is negligible, and development of the nuclei into crystals at higher temperature where nucleation is slow, allowing analysis of their number and obtaining fine polycrystalline structures. For fast crystallizers application of Tammann’s method still is premature, requiring further research for its science-based establishment.Fast scanning calorimetry (FSC) is a new technique to study homogeneous nucleation even in fast crystallizers as it allows subjecting materials to well-defined nucleation and growth conditions. In this project, FSC —together with sophisticated imaging techniques— will be applied for in-depth analysis of homogeneous nucleation in systems composed of large and small organic molecules, including polymers and pharmaceuticals. The nuclei development approach will be further developed to ensure its applicability to these systems and the role of the nuclei-transfer-heating rate as a critical but never before analyzed parameter will be challenged. The employment of large and small molecules with distinct structural features (thus exhibiting different intermolecular forces) will yield valuable information about structure dependence of the nucleation process.The results of the project will promote further development of polymer and pharmaceutical processing technologies, pursuing tailored structures for specific applications. In addition, data will allow reviewing the theoretical background of the nucleation theory, which, so far, does not distinguish between systems composed of different building units.To achieve the goals of the project, capacities available at the Martin Luther University Halle-Wittenberg (Germany), specialized in polymer crystallization and development of polymeric materials with specific properties, and Kazan Federal University (Russia), with expertise in the field of thermodynamics of small organic molecules, will be combined. At both partners, state-of-the-art FSC and imaging tools are available, providing an excellent infrastructure. The different expertise of the participating units will yield synergetic effects towards an enhanced understanding of crystal nucleation to further develop relations between the chemical structure of a material, processing routes, and final properties.

可结晶材料的性质在很大程度上取决于晶体的分数、形态和更高级的组织。晶体生长之前的成核，与核数影响这些参数。控制形核是调整结构形成和材料性能的关键工具。虽然晶体生长和非均质成核已得到很好的研究，但对均质成核的了解却少得多，这主要是由于缺乏分析工具。在高熔体过冷度下的成核可以采用Tammann的两阶段成核方法进行研究，该方法对于缓慢结晶器（例如陶瓷）来说是成熟的。这种方法意味着在生长可以忽略不计的低温下形成核，并且在成核缓慢的较高温度下核发展成晶体，从而允许分析它们的数量并获得精细的多晶结构。对于快速结晶器应用Tammann的方法仍然是不成熟的，需要进一步的研究，其科学为基础的establishment.Fast扫描量热法（FSC）是一种新的技术，研究均匀成核，即使在快速结晶器，因为它可以使材料受到良好定义的成核和生长条件。在该项目中，FSC -与先进的成像技术一起-将用于深入分析由大分子和小分子有机分子组成的系统中的均匀成核，包括聚合物和药物。将进一步发展的核开发方法，以确保其适用于这些系统和核转移加热速率作为一个关键的，但从来没有分析参数的作用将受到挑战。利用具有不同结构特征的大分子和小分子（从而表现出不同的分子间力）将产生关于成核过程的结构依赖性的有价值的信息。该项目的结果将促进聚合物和药物加工技术的进一步发展，追求针对特定应用的定制结构。此外，数据将允许审查成核理论的理论背景，迄今为止，该理论没有区分由不同建筑单元组成的系统。为了实现该项目的目标，专门从事聚合物结晶和开发具有特定性能的聚合物材料的哈勒-维滕贝格马丁路德大学（德国）和喀山联邦大学（俄罗斯）的现有能力，与专业知识领域的热力学小有机分子，将被合并。两家合作伙伴都提供最先进的FSC和成像工具，提供出色的基础设施。参与单位的不同专业知识将产生协同效应，以增强对晶体成核的理解，进一步发展材料化学结构，加工路线和最终性能之间的关系。