Traversari Gabriele, Porcheddu Andrea, Pia Giorgio, Delogu Francesco, Cincotti Alberto
Department of Mechanical, Chemical and Materials Engineering, University of Cagliari, via Marengo 2, 09123 Cagliari, Italy.
Phys Chem Chem Phys. 2021 Jan 6;23(1):229-245. doi: 10.1039/d0cp05647b.
Driven by the promise of alternative synthetic routes to fine chemicals and pharmaceuticals, mechanochemistry is going through a period of intense growth. Mechanical forces are successfully utilized to activate chemical reactions involving an ever-growing variety of inorganic and organic substances with the aim of developing solvent-less processes to be used in the greener chemical industry of tomorrow. Down this path, the proper understanding of the relationships between processing variables, macroscopic transformation kinetics and microscopic chemistry represents one of the fundamental challenges to face. In this work, we develop a kinetic model that, taking into account the intrinsic statistical nature of the mechanical processing of powders by ball milling, combines a phenomenological description of the rheological behaviour of molecular solids with the chemistry of interface reactions. Specifically, we use discrete deformation maps to account for the co-deformation of molecular solids and the consequent increase of the interface area between initially segregated reactants. We assume that the chemical reaction only occurs, with a certain probability, when reactants come into contact due to relocations induced by shearing. No diffusion is allowed. The systematic variation of the amount of powder involved in individual impacts, the composition of powder mixtures and the reaction probability at the interface provide us with a complete overview of the kinetic scenario. In particular, we present the different kinetic curves that can be originated from interface reaction, pointing out how statistical, mixing and chemical factors affect the mechanochemical kinetics. Eventually, we suggest how experimental findings can be used to gain information on the underlying mechanochemistry based on the outcomes of our kinetic modeling.
在通往精细化学品和药物的替代合成路线的前景推动下，机械化学正经历着一段快速发展的时期。机械力已成功用于激活涉及越来越多无机和有机物质的化学反应，目的是开发无溶剂工艺，以应用于未来更绿色的化学工业。沿着这条道路，正确理解加工变量、宏观转变动力学和微观化学之间的关系是面临的基本挑战之一。在这项工作中，我们开发了一个动力学模型，该模型考虑了球磨对粉末进行机械加工的内在统计性质，将分子固体流变行为的唯象描述与界面反应化学相结合。具体而言，我们使用离散变形图来解释分子固体的共同变形以及由此导致的初始分离反应物之间界面面积的增加。我们假设化学反应仅在由于剪切引起的重新定位使反应物接触时，以一定概率发生。不允许扩散。单个冲击中涉及的粉末量、粉末混合物的组成以及界面处的反应概率的系统变化，为我们提供了动力学情况的完整概述。特别是，我们展示了可由界面反应产生的不同动力学曲线，指出统计、混合和化学因素如何影响机械化学动力学。最后，我们建议如何根据我们动力学建模的结果，利用实验发现来获取有关潜在机械化学的信息。
