Preparation Of Chitosan/nano Silver-waterborne Polyurethane Thin Composite Film And Its Application In Antibacterial Packaging

Compared with the traditional packaging materials,the physical,chemical and biological properties(stability,antibacterial,preservation,etc.)of nanocomposite packaging materials are significantly improved.Waterborne polyurethane(WPU)is widely used in coatings,printing ink,textiles and other fields because of its good mechanical properties,non-pollution,non-toxicity and other advantages.However,WPU is easily contaminated by external bacteria due to its water absorption.Silver nanoparticles(Ag NP s)have good antibacterial properties and biocompatibility,and some scholars had combined them with WPU,which has attracted wide attention in the biomedical field.Chitosan(CS)polymer material has good biodegradability and biocompatibility,and has been widely used in the field of suppressive research of bacteria and fungi.However,the mechanical properties of chitosan are poor and its bacteriostatic effect is affected by many factors Therefore,the preparation of chitosan/nanometer Silver-waterborne polyurthane(CS/Ag-WPU)composite films,on the one hand,can use the combination of chitosan and nanometer silver to produce a cooperative application,enhance the stability of Ag NPs,and solve the problem of Ag NPs agglomeration.On the other hand,nanoparticles can improve the antibacterial and physical properties of composite filmsIn this paper,the Ag NPs with uniform particle size distribution and size less than 10nm were successfully prepared by chemical reduction method with tannic acid as the reducing agent and trisodium citrate as the auxiliary reducing agent and stabilizer.WPU was prepared from diisocyanate and polyethylene glycol,and nano silver-waterborne polyurethane(Ag-WPU)composite films were prepared by physical composite.The results show that the surface of the composite film is flat and has good stability at low temperature and water resistance.Antibacterial experiments showed that Ag-WPU composite films showed good inhibitory effect on escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).With the increase of Ag NPs,the inhibitory effect of compound film on E.coil is stronger than that of S.aureus,so it has potential application value in antibacterial packaging fieldIn addition,CS solution was used as a dispersant for silver nitrate to chemically reduce silver nitrate to prepare chitosan/nano silver(CS/Ag NPs)solution with a size of 2-3nm.CS provided a carrier for Ag NPs particles,and with the increase of the concentration of CS,uniform silver nanoclusters were formed in the solution of CS.CS/Ag NPs solution was mixed with WPU to prepare CS/Ag-WPU thin films.The results show that the surface of the composite film is flat and has good stability at low temperature and water resistance.The antibacterial experiments showed that the CS/Ag-WPU composite film had a good inhibitory effect on escherichia coli(E coli)and Staphylococcus aureus(S.aureus).With the increase of CS concentration,its inhibitory effect on two kinds of bacteria is enhanced,and compound film has a potential application value in antibacterial packaging field,since its inhibitory effect on S.aureus is stronger than that of E coil.