Preparation And Properties Of WO₃/Polyvinyl Alcohol Photo-thermal Antibacterial Composite Films

In recent years,more and more attention has been paid to films with antimicrobialactivity andfilms that monitor food freshness by color response.However,there is still a need to develop multi-functional antimicrobials and colorimetric agents.In this paper,a novel composite films with near infrared(NIR 808 nm)photothermal antibacterial activity and freshness monitoring ability was developed by mixing WO₃ nanorods into polyvinyl alcohol(PVA)matrix.The WO₃ nanorods with high purity and good morphology were prepared by one-step hydrothermal method through p H control.The length of WO₃ nanorods was about 2?m,and the diameter was about 20-80 nm.The nanorods exhibited good antimicrobial activity against E.coli and S.aureus.The sensitivity of WO₃ to H₂S gas and the monitoring results of pork freshness confirmed that WO₃ had colorimic response to H₂S,and had low cytotoxicity to human colon cancer HT-29 model cells.WO₃/PVA composite films with antibacterial activity and freshness monitoring ability was prepared by blending WO₃ with PVA,in which the WO₃ nanorods and PVA were bonded by hydrogen bond.Compared with PVA film,the mechanical properties and barrier properties of the films were significantly improved by the introduction of WO₃nanords.,especially the tensile strength of(WO₃/PVA)₄ composite films increased by52.7%,Young's modulus increased by 400.0%,oxygen transmittance decreased by72.4%,water vapor transmittance decreased by 66.9%.Under the irradiation of NIR808nm,the synergistic effects of physical damage,oxidative stress and temperature increase significantly improved the antibacterial activity of(WO₃/PVA)₄,showing an antibacterial efficiency of 90%against E.coli or beyond 90%against S.aureus.At the same time,(WO₃/PVA)₄ film has colorimetric reaction ability to H₂S,which can effectively monitor pork freshness.In conclusion,WO₃/PVA composite films have broad application prospects inphotothermal antibacterial and food freshness monitoring.The research results can provide technical support and theoretical basis for the design and preparation of similar intelligent packaging materials.