Dynamic covalent bond enabled strong Bio-based polyimide materials with Thermally-driven Adaptivity, healability and recycling

Developing new sustainable materials as plastic replacement has become an urgent task for the rapid accumulation of non-degradable petroleum-based waste plastics. Herein, we report that catalyst-free dynamic reversible exchange operated at room-temperature by Schiff base reaction between dialdehyde cellulose nanofibrils (DACNF) and plant oil-based aliphatic long-chain diamine monomers (LCD). The dynamic imine polymer films are formed using a simple method similar to wet pressing in papermaking, which exhibits excellent mechanical properties and thermally processability for the synergistic of hydrogen bond and dynamic imine bond. The tensile strength and Young's modulus reaches 83.74 MPa and 3.90 GPa, which are significantly higher than those of most traditionally commercial plastics. In addition, the number of hydrogen bonds and dynamic imine bonds from cellulose and dynamic imine polymers are evaluated by molecular dynamics (MD) simulation to gain further insights into the intermolecular interaction. By exploring the mechanism involved in the reversible exchange of dynamic imine bonds and its application in self-healing and recycling, a sustainable adaptive material is expected to be structured. More importantly, the dynamic imine polymers also exhibits excellent water barrier properties, solvent resistance and complete biodegradability, which offers a new strategy for reducing the application of non-degradable plastics.