Reprocessable, repairable, and recyclable (“3R”) vitrimers have experienced rapid development over the past decade and demonstrate significant potential for diverse applications. The creep performance of vitrimers is crucial for their dimensional stability under load-bearing conditions at relatively low temperatures and serves as a key metric for evaluating their reprocessability at high temperatures. However, the impact of dynamic covalent polymer networks (DCPNs) on vitrimer mechanics, particularly creep properties, remains debated. Systematic experimental studies on the creep of vitrimers across a wide temperature range are lacking. We use the classic epoxy vitrimer as a model system to investigate the impact of DCPNs on vitrimer mechanics, especially focusing on the creep and recovery behavior across a wide temperature range, spanning from room temperature to the glass transition temperature (Tg) and further to the topology freezing transition temperature (Tv). We systematically examined the effects of temperature, stress, and catalysts on vitrimer creep, revealing the influence of DCPNs. Our findings demonstrate significant thermo-chemo-mechanical coupling effects in the creep mechanics of vitrimers, a facet not comprehensively acknowledged in existing studies. In addition, at temperatures below Tg, vitrimers exhibit superior creep resistance compared to pure epoxy resin due to metal coordination, ensuring excellent dimensional stability under load-bearing conditions. Conversely, at high temperatures, active bond exchange reactions in vitrimers accelerate creep and result in greater residual deformation, highlighting exceptional reprocessability. This study provides new insights into the materials and mechanics of vitrimers.

中文翻译：

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热化学机械耦合作用下玻璃体的蠕变和恢复


可再加工、可修复和可回收（“3R”）玻璃体在过去十年中经历了快速发展，并展示了各种应用的巨大潜力。玻璃体的蠕变性能对于其在相对较低的温度下承载条件下的尺寸稳定性至关重要，并且是评估其在高温下可再加工性的关键指标。然而，动态共价聚合物网络（DCPN）对 vitrimer 力学，特别是蠕变性能的影响仍然存在争议。缺乏对宽温度范围内玻璃体蠕变的系统实验研究。我们使用经典的环氧 vitrimer 作为模型系统，研究 DCPN 对 vitrimer 力学的影响，特别关注从室温到玻璃化转变温度 (Tg) 并进一步到拓扑冻结转变温度（Tv）。我们系统地研究了温度、应力和催化剂对 vitrimer 蠕变的影响，揭示了 DCPN 的影响。我们的研究结果表明，玻璃体蠕变力学中存在显着的热-化学-机械耦合效应，这一点在现有研究中尚未得到全面认可。此外，在低于Tg的温度下，由于金属配位，与纯环氧树脂相比，vitrimers表现出优异的抗蠕变性，确保了承载条件下优异的尺寸稳定性。相反，在高温下，玻璃体中活跃的键交换反应会加速蠕变并导致更大的残余变形，从而突出了卓越的可再加工性。这项研究为 vitrimer 的材料和力学提供了新的见解。