In this study, a seamless, self‐transformation system of linear thermoplastic polyesters into the sustainable cross‐linked polymers, vitrimers, is demonstrated. The key is the use of polyesters bearing abundant hydroxyl side groups, which are synthesized via the reaction using dithiol molecules bearing ester units and diepoxy molecules. The polymerization reaction progresses efficiently at relatively low temperature due to the click nature of the thiol‐epoxy reaction, which provides the hydroxyl side groups along the polyester chain. The tin catalyst (stannous octoate) is added in the initial polymerization, and the catalyst also works to cross‐link the polyesters via intermolecular transesterification bond exchange simply by heating at high temperatures. By adjusting the degrees of cross‐linking, the mechanical properties as well as the thermal properties are well tuned. The bond exchange can still be activated in the final cross‐linked sample; and thus, the material behaves as vitrimers, exhibiting mechanical recyclability. The application of a new type of hot melt adhesive, where the post‐coating tuning/enhancement of adhesion strength is realized, is also demonstrated. On the whole, the present system is very simple but proposes a new application window of bond exchange concept into self‐transformation polymers.

中文翻译：

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通过键交换引发的交联将热塑性聚酯无缝自转化为 Vitrimer

在这项研究中，展示了线性热塑性聚酯到可持续交联聚合物（vitrimers）的无缝自转化系统。关键是使用带有丰富羟基侧基的聚酯，这些聚酯是通过带有酯单元的二硫醇分子和二环氧分子的反应合成的。由于硫醇-环氧反应的点击性质，聚合反应在相对较低的温度下有效进行，该反应沿聚酯链提供羟基侧基。在初始聚合时添加锡催化剂（辛酸亚锡），该催化剂还可以通过简单地在高温下加热进行分子间酯交换键交换来交联聚酯。通过调整交联度，可以很好地调节机械性能和热性能。在最终的交联样品中键交换仍然可以被激活；因此，该材料表现为玻璃体，表现出机械可回收性。还演示了新型热熔胶的应用，实现了涂布后粘合强度的调整/增强。总的来说，本系统非常简单，但提出了键交换概念在自转化聚合物中的新应用窗口。