Hertel Raphael, Raisch Maximilian, Walter Michael, Reiter Günter, Sommer Michael
Department of Polymer Chemistry, Institute for Chemistry, Chemnitz University of Technology, Str. der Nationen 62, 09111, Chemnitz, Germany.
FIT Freiburg Center for Interactive Materials and Bioinspired Technologies, Albert-Ludwig-University of Freiburg, Georges-Köhler-Allee 105, 79110, Freiburg, Germany.
Angew Chem Int Ed Engl. 2024 Dec 2;63(49):e202409369. doi: 10.1002/anie.202409369. Epub 2024 Oct 17.
Sterically distorted donor-acceptor π-systems, termed DA springs, can be progressively planarized under mechanical load causing a bathochromic shift of the photoluminescence (PL) spectrum. By combining theory and experiment, we here use a simple linear force calibration for two different conformational mechanochromophores to determine molecular forces in polymers from the mechanochromic shift in PL wavelength during multiple uniaxial tensile tests. Two systems are used, i) a highly entangled linear glassy polyphenylene and ii) a covalent elastomeric polydimethylsiloxane network. The mean forces estimated by this method are validated using known threshold forces for the mechanochemical ring-opening reactions of two different spiropyran force probes. The agreement between both approaches underlines that these DA springs provide the unique opportunity for the online monitoring of local molecular forces present in diverse polymer matrices.
空间扭曲的供体-受体π体系，即所谓的DA弹簧，在机械负载下可逐渐平面化，导致光致发光（PL）光谱发生红移。通过理论与实验相结合，我们在此对两种不同的构象机械变色团使用简单的线性力校准，以根据多次单轴拉伸试验期间PL波长的机械变色位移来确定聚合物中的分子力。使用了两个体系，i）高度缠结的线性玻璃态聚苯撑和ii）共价弹性聚二甲基硅氧烷网络。通过两种不同的螺吡喃力探针的机械化学开环反应的已知阈值力，验证了用该方法估算的平均力。两种方法之间的一致性强调，这些DA弹簧为在线监测各种聚合物基质中存在的局部分子力提供了独特的机会。
