The sensing of mechanical stress in polymers is indispensable for investigating the origin and propagation of cracks that lead to material failure and for designing mechanically responsive polymers. Here the unique approaches of using the force‐induced switching of aromaticity and homoaromaticity in molecular optical force sensors for the real‐time measurement of mechanical forces acting in stretched polymers are suggested. The mechanical switching of aromaticity in Dewar benzene is an irreversible event, whereas the degree of π‐orbital overlap in homoaromatic compounds like homotropylium can be adjusted progressively over a wide range of forces. Using computational methods, it is demonstrated that both approaches lead to significant changes in the visible part of the UV/Vis spectra of the force sensors upon application of weak forces (pN–nN). Polymers that incorporate such molecular force sensors therefore change their color well before material failure occurs.

中文翻译：

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聚合物分子光学力传感器中芳香性和同芳香性的机械转换

聚合物中机械应力的感测对于调查导致材料失效的裂纹的起源和传播以及设计机械响应性聚合物是必不可少的。在此，提出了在分子光学力传感器中使用力诱导的芳香性和均芳香性转换的独特方法，以实时测量作用于拉伸聚合物中的机械力。杜瓦苯中芳香性的机械转换是不可逆的事件，而高芳香族化合物（如高嗜yl）中的π轨道重叠程度可以在很宽的作用力范围内逐步调节。使用计算方法证明，在施加弱力时，两种方法都会导致力传感器的UV / Vis光谱的可见部分发生显着变化（pN –n N）。因此，结合了这种分子力传感器的聚合物会在发生材料故障之前很好地改变其颜色。