Robust, waterproof, and degradable cellulose-based polyimine vitrimer for plastic replacement

The increasing application of non-degradable petroleum-based plastics has resulted in serious environmental pollution. Renewable and degradable cellulose-based materials are attractive candidates to replace petroleum-based plastics. However, the strong hydrogen bond (H-bond) interactions of cellulose result in its poor plastic formability such as thermoforming. Herein, a novel and effective thermoforming method of cellulose was developed by modifying cellulose into cellulose-based polyimine vitrimer (Cel-PI) via introducing dynamic imine bonds between cellulose molecular chains using Schiff-base reaction. The presence of dynamic imine bonds enables the heat-induced dynamic exchange and stress relaxation behavior of Cel-PI networks, making the excellent thermo-processability of Cel-PI. The as-synthesized Cel-PI powders can be easily thermoformed into Cel-PI film via heat-pressing approach without adding any plasticizers. The resulting Cel-PI film exhibits high Young's modulus (2.9 GPa), high strength (46.3 MPa), good self-healing ability, excellent waterproof capability and organic solvent stability, and high thermal stability. Moreover, it can be chemically degraded, biodegraded, and recycled. Therefore, Cel-PI represents a promising and sustainable petroleum-based plastic replacement.