Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States
Feedback Kinetics in Mechanochemistry: The Importance of Cohesive States
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DOI：
10.1002/anie.201706723
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发表时间：
2017-11-27
影响因子：
16.6
通讯作者：
James, Stuart L.
中科院分区：
文献类型：
--
作者：
Hutchings, Benjamin P.;Crawford, Deborah E.;James, Stuart L.
虽然机械化学合成正变得越来越广泛的应用，甚至商业化，更大的基本理解是需要的，如果该领域的进展少的试错的基础上。我们报告说，在球磨机中的机械化学反应表现出不寻常的S形反馈动力学显着不同的简单的一阶动力学溶液中相同的反应。诱导期之后是反应速率的快速增加，然后随着反应完成，速率再次降低。发现这些不寻常动力学的起源是涉及化学和机械因素的反馈循环。在反应过程中，反应混合物的物理形式从粉末变为粘性橡胶状状态，这导致观察到的反应速率增加。研究表明，非明显的和动态的流变学变化的反应混合物必须理解如何机械化学反应的进展。
Although mechanochemical synthesis is becoming more widely applied and even commercialised, greater basic understanding is needed if the field is to progress on less of a trial-and-error basis. We report that a mechanochemical reaction in a ball mill exhibits unusual sigmoidal feedback kinetics that differ dramatically from the simple first-order kinetics for the same reaction in solution. An induction period is followed by a rapid increase in reaction rate before the rate decreases again as the reaction goes to completion. The origin of these unusual kinetics is found to be a feedback cycle involving both chemical and mechanical factors. During the reaction the physical form of the reaction mixture changes from a powder to a cohesive rubber-like state, and this results in the observed reaction rate increase. The study reveals that non-obvious and dynamic rheological changes in the reaction mixture must be appreciated to understand how mechanochemical reactions progress.