Although considerable progress has been made in developing different types of vitrimers, ongoing challenges remain in tuning their mechanical and rheological properties, self-healing, and adhesion. Here, we demonstrate a one-pot method to produce a novel double-network epoxy vitrimer using an aliphatic amine cross-linker with a siloxane covalent bond and an aromatic amine cross-linker with a disulfide covalent bond. When a controlled two-stage curing process is employed, the markedly different reactivities of aliphatic amine and aromatic amine with epoxy allow for sequential cross-linked network formation, leading to the development of a double network that incorporates two types of dynamic covalent bonds. As a result, the produced vitrimers exhibit controllable mechanical, thermal, and rheological properties, as well as recyclability. This is evidenced by a tensile strength as high as 72 MPa, while maintaining ∼10% elongation at break, a wide glass-transition temperature range from 91 to 171 °C, and an adjustable two-stage stress relaxation. These characteristics suggest opportunities to develop high-performance cross-linked polymers with specific responses to time and temperatures.

中文翻译：

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一锅法制备高性能、可回收、两阶段应力松弛的双网络环氧Vitrimer


尽管在开发不同类型的玻璃体方面已经取得了相当大的进展，但在调整其机械和流变性能、自修复和粘附力方面仍然存在持续的挑战。在这里，我们展示了一种使用具有硅氧烷共价键的脂肪胺交联剂和具有二硫共价键的芳香胺交联剂生产新型双网络环氧玻璃体的一锅法。当采用受控的两阶段固化过程时，脂肪胺和芳香胺与环氧树脂的反应活性明显不同，从而可以顺序形成交联网络，从而形成包含两种类型动态共价键的双网络。因此，所生产的玻璃体表现出可控的机械、热和流变性能以及可回收性。高达 72 MPa 的拉伸强度、同时保持约 10% 的断裂伸长率、91 至 171 °C 的宽玻璃化转变温度范围以及可调节的两阶段应力松弛就证明了这一点。这些特性表明有机会开发对时间和温度具有特定响应的高性能交联聚合物。