Department of Organic and Polymeric Materials, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan).
Graduate School of Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395 (Japan).
Angew Chem Int Ed Engl. 2015 May 18;54(21):6168-72. doi: 10.1002/anie.201412413. Epub 2015 Mar 30.
Visualization and quantitative evaluation of covalent bond scission in polymeric materials are highly important for understanding failure, fatigue, and deterioration mechanisms and improving the lifetime, durability, toughness, and reliability of the materials. The diarylbibenzofuranone-based mechanophore radical system enabled, through electron paramagnetic resonance spectroscopy, in situ quantitative evaluation of scission of the mechanophores and estimation of mechanical energy induced along polymer chains by external forces. The coagulation of polymer solutions by freezing probably generated force but did not cleave the mechanophores. On the other hand, cross-linking led to efficient propagation of the force of more than 80 kJ mol(-1) to some mechanophores, resulting their cleavage and generation of colored stable radicals. This mechanoprobe concept has the potential to elucidate other debated issues in the polymer field as well.
可视化和定量评估聚合材料中共价键的断裂对于理解失效、疲劳和降解机制以及提高材料的使用寿命、耐久性、韧性和可靠性非常重要。基于二芳基双苯并呋喃酮的机械感生自由基体系通过电子顺磁共振波谱能够实现机械感生断裂的原位定量评估，并估计外力沿聚合物链诱导的机械能。聚合物溶液的冷冻凝聚可能产生力，但不会断裂机械感生剂。另一方面，交联导致超过 80 kJ/mol 的力有效地传递到一些机械感生剂上，导致它们的断裂并产生有色稳定自由基。这种机械探针概念有可能阐明聚合物领域中其他有争议的问题。
