Micro-crosslinking modification of starch/PBAT/ZnO nanocomposite films and its application in food preservation

Recent progress in antibacterial biodegradable food packaging materials based on starch and ZnO nanoparticles has advanced sustainable plastic alternatives; however, challenges such as poor processability from high starch content, mechanical deficiencies, and nanoparticle migration risks persist, limiting their practical applications. Herein, ZnO nanoparticles were selected as the antibacterial agent, and a micro-crosslinking network was engineered to bridge 70 wt% plasticized hydroxylpropyl distarch phosphate (HPS) and poly(butylene adipate-co-terephthalate) (PBAT). The micro-crosslinked network not only enhances melt strength, improving processability, but also transforms the phase structure from a loose layered morphology to a compact bicontinuous architecture. This structural transformation enhances interfacial compatibility, and its combination with the reinforcement effect of ZnO nanoparticles synergistically improves mechanical performance. The tensile strength reaches 14.1 MPa, while the elongation at break increases 8.4 times, reaching 684 %, which surpasses most reported PBAT/thermoplastic starch (TPS) blends. More notably, the excellent antibacterial activity and UV resistance of ZnO extend the shelf life of avocado to 16 days, and the micro-crosslinking structure reduces the migration amount of ZnO (<10 mg/dm²), which ensures food safety. This work highlights the potential of micro-crosslink engineering to advance high-performance, eco-friendly food packaging systems.