A backbone lever-arm effect enhances polymer mechanochemistry
A backbone lever-arm effect enhances polymer mechanochemistry
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DOI：
10.1038/nchem.1540
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发表时间：
2013-02-01
期刊：
影响因子：
21.8
通讯作者：
Craig, Stephen L.
中科院分区：
文献类型：
--
作者：
Klukovich, Hope M.;Kouznetsova, Tatiana B.;Craig, Stephen L.
沿着聚合物主链的机械力沿着可用于在嵌入的机械活性官能团中产生显著的反应性，但很少关注给定的聚合物主链如何将该力传递给反应物。在这里，单分子力光谱法被用来直接量化和比较与沿着沿着顺式聚丁二烯和顺式聚丁二烯的主链固定的偕-二溴和偕-二氯环丙烷的开环相关的力。相对于聚丁二烯，聚异戊二烯支架中异构化的临界力下降约三分之一。该效应的根源在于通过聚异戊二烯主链的更有效的化学机械偶联，其充当比聚丁二烯具有更大机械优势的现象学杠杆。实验结果的计算支持，并提供了一个新的策略，工程机械化学反应的基础。
Mechanical forces along a polymer backbone can be used to bring about remarkable reactivity in embedded mechanically active functional groups, but little attention has been paid to how a given polymer backbone delivers that force to the reactant. Here, single-molecule force spectroscopy was used to directly quantify and compare the forces associated with the ring opening of gem-dibromo and gem-dichlorocyclopropanes affixed along the backbone of cis-polynorbornene and cis-polybutadiene. The critical force for isomerization drops by about one-third in the polynorbornene scaffold relative to polybutadiene. The root of the effect lies in more efficient chemomechanical coupling through the polynorbornene backbone, which acts as a phenomenological lever with greater mechanical advantage than polybutadiene. The experimental results are supported computationally and provide the foundation for a new strategy by which to engineer mechanochemical reactivity.