Due to its high specificity and reliability, “click chemistry” has become a valuable tool to prepare functional materials in several research disciplines. Apart from the modular and orthogonal approach, the number of “click” reactions that can exhibit reversibility of the covalent linkages is very few. The chemical structure of 1,2,4-triazoline-3,5-dione (TAD) is almost analogous to widely renowned maleimide, which has been enormously exploited as a dienophile in dynamic Diels–Alder (DA) click conjugation with furfuryl moieties at a relatively slower rate and elevated temperature. Herein, a new class of a reversible electrophilic substitution (ES) “click” pathway has been introduced for straightforward postpolymerization modification of furan polymethacrylate, synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization using TAD derivatives. The suitable (forward and backward) reaction pathway of TAD-derived “click” conjugation was elucidated via the density functional theory (DFT) study. The reversibility within the TAD-derived new σ-covalent bonds at an elevated temperature was evidenced by the DFT study and differential scanning calorimetry (DSC) analysis and was further elucidated by “trans-ES-click” chemistry. A rheology experiment with a temperature sweep was performed to study the alteration of moduli, complex viscosity, and relative cross-link density of the TAD-derived polymer networks at different temperatures and at different TAD contents. The dynamism of furfuryl–TAD “ES-click” conjugation within cross-linked polymer enabled healing of its microscratch, which was monitored using an optical microscope and exemplified in the present perspective.

中文翻译：

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涉及糠醛和三唑啉二酮官能团的快速“ ES单击”反应，用于设计可修复的聚甲基丙烯酸酯

由于其高度的特异性和可靠性，“点击化学”已成为在多个研究学科中制备功能材料的有价值的工具。除了模块化和正交方法外，能够显示共价键可逆性的“点击”反应的数量很少。1,2,4-三唑啉-3,5-二酮（TAD）的化学结构几乎与广为人知的马来酰亚胺类似，后者在动态Diels-Alder（DA）点击偶联中与糠基部分共轭，已被广泛用作亲二烯体。相对较慢的速度和较高的温度。在此，为了对呋喃聚甲基丙烯酸酯进行简单的后聚合修饰，引入了一种新的可逆亲电取代（ES）“点击”途径。通过使用TAD衍生物的可逆加成-断裂链转移（RAFT）聚合合成。通过密度泛函理论（DFT）研究阐明了TAD衍生的“喀哒”共轭反应的合适（正向和反向）反应途径。DFT研究和差示扫描量热法（DSC）分析证明了TAD衍生的新σ-共价键在高温下的可逆性，并通过“ trans-ES-click”化学进一步阐明了这一点。进行了带有温度扫描的流变实验，以研究在不同温度和不同TAD含量下，TAD衍生的聚合物网络的模量，复数粘度和相对交联密度的变化。交联聚合物中糠基-TAD“ ES-click”偶联的活力使得其微划痕得以修复，