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A Polymer with Mechanochemically Active Hidden Length
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2020-10-16 , DOI: 10.1021/jacs.0c09220
Yancong Tian 1 , Xiaodong Cao 2 , Xun Li 3 , Huan Zhang 2 , Cai-Li Sun 1 , Yuanze Xu 2 , Wengui Weng 2 , Wenke Zhang 3 , Roman Boulatov 1
Affiliation  

Incorporating hidden length into polymer chains can improve their mechanical properties, because release of the hidden length under mechanical loads enables localized strain relief without chain fracture. To date, the design of hidden length has focused primarily on the choice of the sacrificial bonds holding the hidden length together. Here we demonstrate the advantages of adding mechanochemical reactivity to hidden length itself, using a new mechanophore that integrates (Z)-2,3-diphenylcyclobutene-1,4-dicarboxylate, with hitherto unknown mechanochemistry, into macrocyclic cinnamate dimers. Stretching a polymer of this mechanophore more than doubles the chain contour length without fracture. DFT calculations indicate that the sequential dissociation of the dimer, followed by cyclobutene isomerization at higher forces yields a chain fracture energy 11 times that of a simple polyester of the same initial contour length and preserves high energy-dissipating capacity up to ∼3 nN. In sonicated solutions cyclobutene isomerizes to two distinct products by competing reaction paths, validating the computed mechanochemical mechanism and suggesting an experimental approach to quantifying the distribution of single-chain forces under diverse loading scenarios.

中文翻译:

具有机械化学活性隐藏长度的聚合物

将隐藏长度加入聚合物链可以提高它们的机械性能,因为在机械载荷下隐藏长度的释放可以实现局部应变消除而不会断裂。迄今为止,隐藏长度的设计主要集中在选择将隐藏长度结合在一起的牺牲键上。在这里,我们展示了将机械化学反应性添加到隐藏长度本身的优势,使用一种新的机械载体,将 (Z)-2,3-diphenylcyclobutene-1,4-dicarboxylate 与迄今为止未知的机械化学整合到大环肉桂酸二聚体中。拉伸这种机械载体的聚合物会使链轮廓长度增加一倍以上而不会断裂。DFT 计算表明二聚体的顺序解离,然后在更高的力下环丁烯异构化产生的链断裂能是相同初始轮廓长度的简单聚酯的 11 倍,并保持高达 ~3 nN 的高能量耗散能力。在超声处理溶液中,环丁烯通过竞争反应路径异构化为两种不同的产物,验证计算的机械化学机制并提出一种实验方法来量化不同负载情况下单链力的分布。
更新日期:2020-10-16
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