Experimentally realized mechanochemistry distinct from force-accelerated scission of loaded bonds
Experimentally realized mechanochemistry distinct from force-accelerated scission of loaded bonds
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DOI：
10.1126/science.aan1026
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发表时间：
2017-07-21
期刊：
影响因子：
56.9
通讯作者：
Boulatov, Roman
中科院分区：
文献类型：
--
作者：
Akbulatov, Sergey;Tian, Yancong;Boulatov, Roman
拉伸聚合物链加速各种内部共价键的解离，达到与易裂键所经历的力良好相关的程度。最近的理论还预测了这样的情况，即施加的力加速了未加载键的解离，并在动力学上加强了应变键。我们在这里报告明确的实验验证这一假设：详细的动力学测量表明，拉伸磷酸三酯加速解离的卸载磷-氧键正交的拉轴，而拉伸有机硅氧烷抑制解离的对齐加载硅-氧键。定性地，结果是由磷酸酯伸长和硅氧烷收缩沿着拉轴在各自的速率决定过渡态。定量分析表明，该结果符合一个简单的力化学动力学模型。
Stretching polymer chains accelerates dissociation of a variety of internal covalent bonds, to an extent that correlates well with the force experienced by the scissile bond. Recent theory has also predicted scenarios in which applied force accelerates dissociation of unloaded bonds and kinetically strengthens strained bonds. We report here unambiguous experimental validation of this hypothesis: Detailed kinetic measurements demonstrate that stretching phosphotriesters accelerates dissociation of the unloaded phosphorus-oxygen bond orthogonal to the pulling axis, whereas stretching organosiloxanes inhibits dissociation of the aligned loaded silicon-oxygen bonds. Qualitatively, the outcome is determined by phosphoester elongation and siloxane contraction along the pulling axis in the respective rate-determining transition states. Quantitatively, the results agree with a simple mechanochemical kinetics model.