The reprocessing stability and recyclability of bio-based thermosetting materials have positive environmental and economic values. In this work, two types of lignocellulosic polyimide vitrimers were developed from two lignin-derived aldehyde monomers and a cellulose-derived diamine monomer based on a dynamic covalent adaptive network. Both polyimide vitrimers demonstrated high fracture strengths of up to 67.5 and 40.2 MPa, and the vitrimers had no obvious dissolution and weight change after soaking in ten common solvents for 30 days. Similar to other literature reports, the vitrimers still maintained more than 92% fracture strength after 5 fracture–hot-press cycles. Besides, due to the presence of large amounts of nitrogen and phosphorus elements, both vitrimers exhibited good flame-retardant properties: they could self-extinguish in 10 s while removing the flame after ignition and generated no molten droplets. More importantly, these two highly cross-linked thermoset materials were efficiently transformed back into related monomers, guaranteeing excellent monomer–polymer–monomer closed-loop recycling. The stable cycle processability and efficient closed-loop recovery of lignocellulosic thermosetting materials provided the possibility of the efficient utilization of biomass materials. Furthermore, the successful preparation of basalt fiber composites with high mechanical properties and easy recovery demonstrated the application potential of these vitrimers.

中文翻译：

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稳定而强大的木质纤维素聚酰亚胺三聚体，具有良好的可再加工性和闭环可回收性


生物基热固性材料的再加工稳定性和可回收性具有积极的环境和经济价值。在这项工作中，从两种木质素衍生的醛单体和一种基于动态共价自适应网络的纤维素衍生的二胺单体开发了两种类型的木质素纤维素聚酰亚胺三聚体。两种聚酰亚胺三聚体均表现出高达 67.5 和 40.2 MPa 的高断裂强度，并且在 10 种常用溶剂中浸泡 30 d 后，三聚体没有明显的溶解和重量变化。与其他文献报道类似，vitrimers 在 5 次断裂-热压循环后仍保持超过 92% 的断裂强度。此外，由于存在大量的氮和磷元素，两种 vitrimer 都表现出良好的阻燃性能：它们可以在 10 s 内自熄，同时在点火后去除火焰，并且不会产生熔融液滴。更重要的是，这两种高度交联的热固性材料被有效地转化回相关的单体，保证了出色的单体-聚合物-单体闭环回收。木质纤维素热固性材料稳定的循环加工性和高效的闭环回收为生物质材料的高效利用提供了可能性。此外，成功制备具有高力学性能和易恢复的玄武岩纤维复合材料证明了这些 vitrimers 的应用潜力。