Study Of Self-antibacterial And Reversible Self-healing Antibacterial Polyurethane Coatings

Over the past few decades,medical science has improved continuously,but with the abuse of antibiotics,diseases caused by bacterial infection is becoming a major safety hazard to public health,and the antibacterial coating is an important weapon for humans to fight against bacteria.Polyurethane,as a material,is widely used in the field of antibacterial coatings as its excellent mechanical properties,adjustable molecular structure and good biocompatibility.This thesis carried out a series study of the preparations,applications and working principles of antibacterial polyurethane coatings,which including two parts:（1）Synthesis and properties of self-antibacterial UV-curable cationic waterborne polyurethane acrylates.The UV-curable waterborne polyurethane with pendent amine（PWPU）and modified by GAA was designed and synthesized using the chain extension-blocking-neutralization method.The dispersions and coatings of PWPU and linear structure waterborne UV polyurethane with backbone amine（LWPU）for their difference in reactivity,particle size,dispersion stability,heat decomposition resistance,etc.were studied and compared by FTIR,UV-Vis spectroscopy,Zeta potential,dispersion stability,and TG-DSC.The reliability of the coating was verified by experiments with mechanical properties and chemical resistance.In addition,GAA was attached to the side of the molecular chain to form a macromolecular QAS with guanidino group,and the antibacterial properties and mechanical properties of the dispersion and its cured coating was also investigated after the introduction of GAA.The results show that the method improves dispersion stability and self-antibacterial performance of cationic waterborne polyurethane obviously,PWPU can kill more than90%of bacteria in 4h,and the antibacterial rate is 50%higher than LWPU.AFM shows that the pendant amine and GAA increase the hydrophilic groups of surface,leading to improve the Antibacterial properties.The preparation method has the advantages of simplicity,cheapness and greenness,provides a new idea for the preparation of PWPU,and has potential in the application of antibacterial materials.（2）Synthesis and properties of Diels-Alder reversible self-healing polyurethane coating with antibacterial function.Based on the Diels-Alder reaction principle,a bicyclic Diels-Alder reversible self-healing polyurethane（DAPU）resin,as a matrix material for the coating,was synthesized and prepared by stepwise chemical grafting of PCL,IPDI,FA and BMI,and then mixed the green antibacterial agent GAA to obtain an antibacterial coating（DAPU-GAA）.After detection and analyzing by TG,different size scratch test and optical microscope,DAPU coating has the necessary molecular mobility and thermodynamic reversibility to achieve self-healing function,it can repair micro scratches and large-size traces or breaks at room temperature and 115°C,respectively.Basic coating and mechanical performance tests show that the coating has good gloss,high mechanical strength（19MPa）,and excellent self-healing efficiency.We also examined the effect of the GAA content on the coating properties,and found that the DAPU-GAA coating had more than 70%killing effect on E.coli through subsequent antibacterial tests.Meanwhile,the antibacterial property of the coating is also has a self-repairing function,and its antibacterial efficiency does not change significantly with the number of self-repairs.In addition,the self-healing failure process of the coating was studied by electrochemical method,which is flat and then accelerated.Both DAPU and DAPU-GAA had good anti-corrosion performance and the corrosion currents were 4.457×10^-9 and 8.414×10^-8A,respectively.