Shear-activated chemisorption and association of cyclic organic molecules
Shear-activated chemisorption and association of cyclic organic molecules
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环状有机分子的剪切激活化学吸附和缔合
DOI：
10.1039/d2fd00086e
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发表时间：
2022
影响因子：
3.4
通讯作者：
Martini, Ashlie
中科院分区：
文献类型：
--
作者：
Bhuiyan, Fakhrul H.;Li, Yu-Sheng;Kim, Seong H.;Martini, Ashlie
机械力化学活化为无溶剂化学合成、聚合物加工和润滑等应用创造了新的机会。然而，对这些过程的力学理解仍然是有限的，因为体系的机械力化学响应是许多变量的复杂函数，包括外加应力的方向和非平衡条件下反应物的化学特征。在这里，我们研究了简单的环状有机分子的剪切活化反应，以分离化学结构对反应产率和反应途径的影响。用反应分子动力学模拟了甲基环戊烷、环己烷和环己烯在二氧化硅表面之间的压力和剪切力作用下的模型。环己烯比甲基环戊烷或环己烷更容易被氧化化学吸附和随后的齐聚反应的机械力化学激活。齐聚趋势与球面滑动实验测得的剪切驱动聚合产率一致。对模拟结果的分析显示了发生氧化化学吸附的碳原子位置的分布，并确定环己烯中的双键是其剪切敏感性的来源。最后，确定了最常见的缔合反应路径，提供了对前体分子的化学结构如何决定其对机械力化学激活的反应的洞察。
Mechanochemical activation has created new opportunities for applications such as solvent-free chemical synthesis, polymer processing, and lubrication. However, mechanistic understanding of these processes is still limited because the mechanochemical response of a system is a complex function of many variables, including the direction of applied stress and the chemical features of the reactants in non-equilibrium conditions. Here, we studied shear-activated reactions of simple cyclic organic molecules to isolate the effect of chemical structure on reaction yield and pathway. Reactive molecular dynamics simulations were used to model methylcyclopentane, cyclohexane, and cyclohexene subject to pressure and shear stress between silica surfaces. Cyclohexene was found to be more susceptible to mechanochemical activation of oxidative chemisorption and subsequent oligomerization reactions than either methylcyclopentane or cyclohexane. The oligomerization trend was consistent with shear-driven polymerization yield measured in ball-on-flat sliding experiments. Analysis of the simulations showed the distribution of carbon atom sites at which oxidative chemisorption occurred and identified the double bond in cyclohexene as being the origin of its shear susceptibility. Lastly, the most common reaction pathways for association were identified, providing insight into how the chemical structures of the precursor molecules determined their response to mechanochemical activation.