Green zein-chitosan composite films embedded with wheat straw-derived carbon quantum dots: Enhanced mechanical,...

Achieving the simultaneous improvement of mechanical, degradation, and preservation properties is being a great challenge of current preservation films. Carbon quantum dots (CQDs) are proposed to prepare composite films with excellent mechanical, degradation, and preservation properties based on zein and chitosan. The result showed that the addition of CQDs improved the strength, stiffness, and toughness of zein composite films attributing to the stable and compact network structure formed by electrostatic interaction and hydrogen bonding. Also, adding CQDs promotes the degradation of zein composite films in the water and phosphate-buffered saline (PBS) environment while they alleviated the degradation in the soil environment demonstrating the stability in the soil. Among all the film samples, the composite films formed by zein, chitosan, Polyethylene glycol, and CQDs exhibited the best comprehensive properties with the tensile strength of 24.42 MPa, tensile modulus of 0.93 GPa, elongation at break of 8.39%, hydrolysis rate of 68.37%, PBS degradation rate of 27.48%, buried degradation rate of 71.71%, and preservation life to cherry tomatoes of more than 37 days. The composite films in this study are expected to play a significant role in the field of food preservation films in view of achieving a balance between performance and sustainability.