Dynamic covalent bonds in a polymer network lead to plasticity, reshapability, and potential recyclability at elevated temperatures in combination with solvent-resistance and better dimensional stability at lower temperatures. Here we report a simple one-step procedure for the catalyst-free preparation and intramolecularly catalyzed stress-relaxation of dynamic polyester networks. The procedure is based on the coupling of branched OH-end functional polyesters (functionality ≥ 3) by pyromellitic dianhydride (PMDA) or 2,5-bis(methoxy-carbonyl) benzenesulfonic acid resulting in ester linkages with, respectively, a COOH or a SO₃H group in a position ortho to the ester bond. This approach leads to an efficient external catalyst-free dynamic polyester network, in which the topology rearrangements occur via a dissociative mechanism involving anhydrides. The SO₃H-containing network is particularly interesting, as it shows the fastest stress relaxation and does not suffer from unwanted additional transesterification reactions, as was observed in the COOH-containing network.

中文翻译：

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使用相邻羧酸和磺酸基团的分子内催化动态聚酯网络

聚合物网络中的动态共价键导致高温下的可塑性、可再成型性和潜在的可回收性，以及低温下的耐溶剂性和更好的尺寸稳定性。在这里，我们报告了一种简单的一步程序，用于动态聚酯网络的无催化剂制备和分子内催化应力松弛。该程序基于均苯四酸二酐 (PMDA) 或 2,5-双(甲氧基-羰基) 苯磺酸偶联支化 OH 端官能聚酯（官能度 ≥ 3），从而分别与 COOH 或SO ₃ H 基团位于邻位到酯键。这种方法产生了一个有效的外部无催化剂动态聚酯网络，其中拓扑重排通过涉及酸酐的解离机制发生。含SO ₃ H 的网络特别有趣，因为它显示出最快的应力松弛，并且不会遭受不需要的额外酯交换反应，正如在含 COOH 的网络中所观察到的那样。