The development of novel sustainable materials as plastic replacements has become an urgent task, because the increasing accumulation of nondegradable fossil-based plastic wastes on land and in oceans has led to serious long-term threats to the ecosystem. Herein, a novel type of cellulose-based sustainable material, paper–polyimine composites (PPCs), were developed via the functionalization of cellulose papers using polyimine covalent adaptable networks (CANs). The polyimine infiltrates into the porous structure of cellulose papers and non-covalently bonds to cellulose fiber networks via hydrogen bonding, forming interpenetrating networks. The tensile strength and Young's modulus of PPCs can reach 71 MPa and 3.2 GPa, which are significantly higher than those of most commercially available plastics. The PPCs exhibit good malleability, re-healability, weldability, and moldability. The closed-loop recycling of the polymer matrix and cellulose papers has also been demonstrated. The recycled materials can be 100% reused in the production of next generation composites. More importantly, such PPCs exhibit excellent waterproof performance, superhigh gas (oxygen and moisture) barrier capability, and excellent solvent resistance. Therefore, PPCs represent a novel class of highly green and sustainable materials that can be used as plastic replacements.

中文翻译：

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动态亚胺聚合物可实现可靠，高阻隔且可完全回收的纤维素基塑料替代品

开发新型可持续材料作为塑料替代品已成为当务之急，因为陆上和海洋中不可降解的化石类塑料废物的日益积累对生态系统造成了严重的长期威胁。在此，通过使用聚亚胺共价适应性网络（CAN）对纤维素纸进行功能化，开发了一种新型的纤维素基可持续材料纸-聚亚胺复合材料（PPC ）。聚亚胺渗透到纤维素纸的多孔结构中，并通过氢键，形成互穿网络。PPC的拉伸强度和杨氏模量可以达到71 MPa和3.2 GPa，远高于大多数市售塑料。PPC具有良好的延展性，再修复性，可焊接性和可模塑性。还已经证明了聚合物基质和纤维素纸的闭环再循环。再生材料可以100％地用于下一代复合材料的生产中。更重要的是，这样的PPC具有出色的防水性能，超高的气体（氧气和湿气）阻挡能力以及出色的耐溶剂性。因此，PPC代表了一类新型的高度绿色和可持续的材料，可以用作塑料的替代品。