Given its thermal reversibility, high yield, and minimal side reactions, the Diels–Alder (DA) reaction is a particularly desirable technique for the preparation of polymeric materials with heat-stimulated self-healing properties. A linear self-healing polyurethane containing thermally reversible DA bonds (PU-DA) was developed in this study. Results revealed that the introduction of DA bonds conferred outstanding mechanical property and thermal reversibility to PU-DA films. Thus, the as-prepared PU-DA films demonstrated excellent self-healing performance. The self-healing behavior of the PU-DA films under various heat treatments was examined through qualitative observation and quantitative measurements. The PU-DA underwent self-repair through the combination of two healing actions, i.e., the thermal movement of molecular chains and the thermally reversible DA reaction. Moreover, the self-healing behavior of the PU-DA was repeatable, and the PU-DA continued to present high strength even after undergoing three damage–repair cycles at the same site. In addition, the as-prepared PU-DA exhibited excellent macro-scale self-healing behavior, and it endowed the PU-DA presented reprocessing performance. The PU-DA can be recycled given its excellent self-healing and outstanding reprocessing performances.

中文翻译：

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热处理对热可逆聚氨酯的自修复和加工行为的影响

鉴于其热可逆性，高收率和最小的副反应，Diels–Alder（DA）反应是制备具有热刺激自愈特性的聚合物材料的一种特别理想的技术。在这项研究中开发了包含热可逆DA键（PU-DA）的线性自愈聚氨酯。结果表明，DA键的引入赋予PU-DA膜出色的机械性能和热可逆性。因此，所制备的PU-DA膜表现出优异的自修复性能。通过定性观察和定量测量，研究了PU-DA膜在各种热处理条件下的自愈性能。PU-DA通过两种愈合作用的组合进行自我修复，即 分子链的热运动和热可逆的DA反应。此外，PU-DA的自我修复行为是可重复的，即使在同一位置经历了三个损伤修复周期后，PU-DA仍表现出高强度。另外，所制备的PU-DA表现出优异的宏观尺度自修复行为，并且赋予PU-DA呈现后处理性能。PU-DA具有出色的自我修复和出色的后处理性能，因此可以回收利用。并且赋予了PU-DA更高的后处理性能。PU-DA具有出色的自我修复和出色的后处理性能，因此可以回收利用。并赋予了PU-DA更高的后处理性能。PU-DA具有出色的自我修复和出色的后处理性能，因此可以回收利用。