| In recent years,with the increasing development of cities,bacteria and viruses in the air have also increased,often leading to the occurrence of diseases,which seriously harm human health.With the development of society and the improvement of environmental protection requirements,environmental protection antibacterial coating began to enter people’s life,water-based environmental protection coating is a kind of cross-border coating.It is beneficial to human body and basically pollution-free,with safety and environmental protection,sterilization and deodorization functions.Emulsion polymer is obtained by emulsion polymerization or emulsion copolymerization,which is environmentally friendly and pollution-free.In addition,these materials are typical film forming agents for the preparation of waterborne coatings.There are many kinds of emulsion polymer,but the proportion of bio-based emulsion polymer is small,and its price is usually higher;Therefore,these materials cannot fully meet the practical requirements.In this paper,based on cationic oxidized starch grafting styrene acrylic emulsion,natural antibacterial agents(licorice,tea polyphenols,nutmeg,cinnamon oil)and organic silicon quaternary ammonium salt antibacterial agents(AEM5700)were selected to prepare antibacterial bio-based emulsion with superior comprehensive performance and environmental protection.In addition,a water-based anticorrosive coating with antibacterial bio-based emulsion as the main film forming substance was prepared and studied,which provided a theoretical basis for its application in water-based anticorrosive coating and also had a certain influence on the theoretical development of bio-based related emulsion.Specific research contents are as follows:(1)Four kinds of natural antibacterial agents were selected to prepare different antibacterial starch grafted styrene-acrylic emulsion.The structure of the emulsion and the grafting of the monomer were analyzed by infrared,the particle size and distribution of the emulsion were analyzed by particle size analyzer,and the change of the mass of the emulsion with temperature was analyzed by thermogravimetric analysis,so as to characterize the thermal stability of the emulsion.The bactericidal ability of different groups of emulsion on Escherichia coli and Staphylococcus aureus was studied by bacteriostatic zone test.The results showed that the amount of antibacterial agent had little effect on the basic properties of the emulsion.The particle size of the emulsion was nanometer and the particle size distribution was narrow,which followed the normal distribution curve.According to the bacteriostatic test surface,the antibacterial property of emulsion was better when the proportion of different antibacterial agents in emulsion monomer was 5 wt%.The results showed that the emulsion prepared by cinnamon oil had the best antibacterial activity against Escherichia coli,and the emulsion prepared by tea polyphenol had the best antibacterial activity against aureococcus aureus.(2)Using 3-(trimethoxysilyl)propyl dimethyl ammonium chloride(AEM5700)as antibacterial agent,a novel antibacterial emulsion was prepared by grafting styrene-acrylic acid emulsion onto cationic starch modified by 3-(trimethoxysilyl)propyl dimethyl tetrachylammonium chloride(AEM5700).Because cationic starch and AEM5700 have positive charge,the synergistic bacteriostatic effect is enhanced when exerting bacteriostatic effect.Ammonium ion strongly adsorbed on the surface of bacteria,destroyed the outer surface of bacteria,and destroyed the cell wall.The ammonium ion migrates into the cell,changes its shape,and causes the release of materials inside the cell,leading to the death of the bacteria.The biobased antibacterial emulsion was characterized by FTIR,TGA,SEM,AFM,TEM and contact Angle tests.When the concentration of AEM5700 was 7 wt%,the antibacterial emulsion had better stability and antibacterial performance.Compared with cationic starch grafted styrene-acrylic emulsion,the antibacterial zone increased by 4 ～ 7 mm.(3)On the basis of cationic oxidized starch grafting styrene-acrylic emulsion,at the same time introducing 3-(trimethoxy-silicyl)propyl dimethyl ammonium chloride(AEM5700)and tea polyphenol or cinnamon oil,the antibacterial bio-based composite emulsion was prepared.The biobase composite emulsion has good stability,chemical properties and antibacterial properties.Fourier transform infrared spectroscopy(FTIR)validated the graft polymerization.Thermogravimetric analysis(TGA)showed that the thermal stability of the emulsion was improved.The surface morphology was observed by atomic force microscope.The emulsion after docking was detected by contact Angle test.When the dosage of cinnamon oil and AEM5700 was 5wt%,the biobase antibacterial composite emulsion had better stability and antibacterial properties,respectively.Compared with single antibacterial agent,the antibacterial zone increased by 4 ～ 10 mm.In addition,the polymerization mechanism of bio-based antibacterial emulsion was analyzed.(4)The antibacterial bio-based composite emulsion prepared above is used as the main film forming material to prepare waterborne anticorrosive coatings.the results showed that the basic properties of the anticorrosive coatings reached the best effect when the dosage of quaternary ammonium salt and cinnamon oil was 5 wt%respectively.In the test of salt spray resistance,the coating only has slight corrosion at the lines.In the antibacterial performance test tested by Ingle detection agency,the antibacterial rate of the emulsion made of film forming material reached 92.59%,while the antibacterial rate of starch grafted styrene acrylic emulsion without antibacterial agent was only 55.56%,and the antibacterial rate increased by 37.03%. |
