Facile Fabrication of Sustainable Chitosan Bioplastics Integrating High Strength, Water Resistance, and Closed-Loop Recyclability

Abstract The growing environmental concern over petroleum-based plastics has intensified the demand for sustainable alternatives with high performance and reliable processability. Bio-based plastics have attracted considerable attention as sustainable alternatives to petroleum-derived plastics. However, despite their environmental advantages, their development and application are severely constrained by the necessity for tedious chemical modification and complex processing. Herein, we propose a covalent adaptable network strategy to transform chitosan (CS) into a thermally processable bioplastic through simple and efficient dynamic covalent enamine cross-linking. The enamine bonds enable network rearrangement upon heating, imparting hot-press processability, thermal repairability, and closed-loop recyclability to the material. The resulting bioplastic exhibits a high flexural strength of 189.8 MPa, excellent moisture and solvent resistance, favorable recyclability, high thermal stability, a low thermal expansion coefficient of 1.05 ppm k−1, superior quantitative green chemistry metrics, and rapid soil-burial disintegration. With these advantageous features, the developed bioplastic represents a promising sustainable substitute for conventional petroleum-based plastics.