New dynamic chemistry is nowadays sought to widen the library of accessible covalent adaptable networks (CANs). Here, we investigate the dynamic nature of CO₂-sourced cyclic S,O-acetal bonds under unexplored conditions. Model molecule studies were conducted on various compounds and supported by extensive DFT calculations to understand the required conditions for triggering exchange and the underlying reaction mechanisms. This is the first study to report dynamic S,O-acetal bonds with an unprecedented associative exchange mechanism occurring through nucleophilic attack onto a remote function from the exchanged site. Our findings were translated to macromolecular engineering with the successful production of CO₂-sourced CANs embedding cyclic S,O-acetal bonds from bifunctional alkylidene cyclic carbonates and polythiols. The polymer properties were tuned by the use of structurally divergent monomers, affording materials with distinct thermal and mechanical properties (e.g. T_g ranging from 2 to 51 °C). Complex relaxation behaviour was recorded by rheology experiments, suggesting concurrent exchange reactions to take place at elevated temperatures. The materials dynamics was leveraged through recycling by compression molding for over five cycles. Furthermore, a proof-of-concept coating application was developed, showcasing damage healing at high temperatures.

中文翻译：

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CO2 来源的环状 S,O-缩醛共价适应性网络中前所未有的缔合交换

如今，人们正在寻求新的动态化学来扩大可访问的共价适应性网络（CAN）的库。在这里，我们研究了在未探索的条件下CO ₂来源的环状S , O-缩醛键的动态性质。对各种化合物进行了模型分子研究，并得到广泛的 DFT 计算的支持，以了解触​​发交换所需的条件和潜在的反应机制。这是第一项报告动态S , O-缩醛键的研究，该键具有前所未有的缔合交换机制，通过从交换位点对远程功能进行亲核攻击而发生。我们的研究结果被转化为大分子工程，成功生产了来自CO ₂的CAN，该CAN由双功能亚烷基环状碳酸酯和多硫醇嵌入环状S、O-缩醛键。通过使用结构不同的单体来调节聚合物性能，提供具有不同热性能和机械性能的材料（例如，T _g范围为 2 至 51 °C）。流变学实验记录了复杂的松弛行为，表明在高温下同时发生交换反应。通过压缩成型回收超过五个周期，充分利用了材料的动态特性。此外，还开发了一种概念验证涂层应用，展示了高温下的损伤愈合。