Du Mengqi, Houck Hannes A, Yin Qiang, Xu Yewei, Huang Ying, Lan Yang, Yang Li, Du Prez Filip E, Chang Guanjun
State Key Laboratory of Environment-friendly Energy Materials & School of Materials and Chemistry, Southwest University of Science and Technology, Mianyang, 621010, P. R. China.
Polymer Chemistry Research Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281 S4-bis, B-9000, Ghent, Belgium.
Nat Commun. 2022 Jun 9;13(1):3231. doi: 10.1038/s41467-022-30972-7.
Force-reversible C-N bonds, resulting from the click chemistry reaction between triazolinedione (TAD) and indole derivatives, offer exciting opportunities for molecular-level engineering to design materials that respond to mechanical loads. Here, we displayed that TAD-indole adducts, acting as crosslink points in dry-state covalently crosslinked polymers, enable materials to display reversible stress-responsiveness in real time already at ambient temperature. Whereas the exergonic TAD-indole reaction results in the formation of bench-stable adducts, they were shown to dissociate at ambient temperature when embedded in a polymer network and subjected to a stretching force to recover the original products. Moreover, the nascent TAD moiety can spontaneously and immediately be recombined after dissociation with an indole reaction partners at ambient temperature, thus allowing for the adjustment of the polymer segment conformation and the maintenance of the network integrity by force-reversible behaviors. Overall, our strategy represents a general method to create toughened covalently crosslinked polymer materials with simultaneous enhancement of mechanical strength and ductility, which is quite challenging to achieve by conventional chemical methods.
三唑啉二酮（TAD）与吲哚衍生物之间的点击化学反应产生的力可逆C-N键，为分子水平工程设计响应机械负载的材料提供了令人兴奋的机会。在这里，我们展示了TAD-吲哚加合物作为干态共价交联聚合物中的交联点，使材料在环境温度下就能实时显示可逆的应力响应性。虽然放能的TAD-吲哚反应会导致形成稳定的加合物，但当它们嵌入聚合物网络并受到拉伸力时，在环境温度下会解离以恢复原始产物。此外，新生的TAD部分在解离后能在环境温度下与吲哚反应伙伴自发且立即重新结合，从而通过力可逆行为调整聚合物链段构象并维持网络完整性。总体而言，我们的策略代表了一种创建具有同时增强机械强度和延展性的增韧共价交联聚合物材料的通用方法，这是传统化学方法很难实现的。
