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Preparation and Properties of the Ag-based Hydrophobic Antibacterial Coating

Author: YouWenHui
Tutor: YangHui
School: Zhejiang University
Course: Materials Science and Engineering
Keywords: Ag/TiO2 Ag nanoparticle fluoro-silicone-acrylic emulsionfluoro-silicone resin composite coating surface modification micro/nano structure hydrophobic property antibacterial property
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Type: Master's thesis
Year: 2014
Downloads: 5
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Abstract


Bacteria have a strong ability to attach to material surface, leading to the formation of biofilm, which seriously menaces the health and life of mankind. In recent years, developing antibacterial composite materials based on the organics with low energy surface and the inorganic antibacterial materials can combine the advantages of reduction of bacterial adhesion and killing bacterial property, thereby improving the antibacterial and fouling resistance properties of the material surface. This research topic has become an important development trend of antibacterial material. In this paper, Ag/TiO2powder antibacterial agent and the mesoporous silica microcapsule-supported Ag nanoparticles (MSMAs) sustained-released antibacterial agent were respectively used to combine with the low surface energy fluorine-based polymer, thus successfully fabricating the Ag/TiO2hydrophobic antibacterial coating and the lotus-leaf-like surface MSMAs/FSR super-hydrophobic antibacterial coating, leading to the improvement of antibacterial property. The main contents and conclusions are as follows:(1) Surface modification and characteristics of the Ag/TiO2powder. Vinyltriethoxysilane (VTES) was used to modify the inorganic Ag/TiO2powder. The influences of VTES dosage, reaction temperature and reaction time on the modification of powder were investigated, and the surface morphology, infrared spectra, hydrophobic property and antibacterial property were also analyzed. The results indicate that:the Si-O-Ti bond have formed through the reaction of the silanols generated from the hydrolysis of VTES and the surface hydroxyls of Ag/TiO2powder, thereby realizing the surface modification of Ag/TiO2powder. The optimal modification process conditions are:2g of Ag/TiO2,2mL of VTES, reaction temperature of40℃and reaction time of5h. Under the optimal process conditions, the average particle size of the modified Ag/TiO2powder is0.276μm, and the water contact angle of the powder tablet is increased from53.3°to149.4°. The antibacterial activity of Ag/TiO2powder is not decreased by the modification, and the antibacterial activity against Escherichia coli (E. coli) still remains high level of99.4%.(2) Preparation and characteristics of the Ag/TiO2hydrophobic antibacterial coating. The fluoro-silicone-acrylic emulsion is synthesized by emulsion polymerization and blending process, and then composited with the modified Ag/TiO2 powder to prepare the Ag/TiO2hydrophobic antibacterial coating with the hydrophobic and antibacterial properties. The influences of preparation process on the emulsion stability and coating adhesion were investigated, and the morphology, hydrophobic property and antibacterial property of the as-prepared Ag/TiO2hydrophobic antibacterial coating were also studied. The results indicate that:the optimal synthetic process conditions of the fluoro-silicon-acrylic emulsion are obtained as follows:the mixed emulsifier dosage is7%of the monomers; the initiator dosage is0.4%of the monomers; the polymerization temperature is70℃; the polymerization time is4h; the mass ratio of the fluoro-acrylic emulsion to the silicone-acrylic emulsion is10/90. When the content of the modified Ag/TiO2powder is1%, which ensures good paint stability and coating adhesion, the micro-nano dual roughness apophysis structure is formed on the coating surface. The water contact angle of composite coating is improved from98.2°for the single fluoro-silicone-acrylic coating to120.9°, and the antibacterial activity against E. coli has enhanced from51.1%for the single fluoro-silicone-acrylic coating to93.2%.(3) Fabrication and characteristics of the lotus-leaf-like hydrophobic antibacterial coating. The MSMAs with sustained-released antibacterial property and fluoro-silicone resin (FSR) were used to fabricate a super-hydrophobic antibacterial coating with the lotus-leaf-like surface structure. The influence of the spin-coating process on the surface morphology of the coating was investigated, and the morphology, hydrophobic property and antibacterial property of the as-prepared super-hydrophobic antibacterial coating were also studied. The results indicate that: the optimal spin-coating conditions for fabricating the lotus-leaf-like MSMAs/FSR super-hydrophobic antibacterial coating are as follows:1.3mL of the fluoro-silicone resin solution, spin-coating speed of2000rmp, spin-coating time of lmin;32mg/mL of the MSMAs dispersion, spin-coating speed of800rmp;0.6mL of the fluoro-silicone resin solution for surface modification. Owing to the lotus-leaf-like dual micro-nano roughness structure, the water contact angle of the coating is improved from112.0°for the single fluoro-silicone coating to150.4°; The as-prepared coating combines the bacteriostasis ability of the super-hydrophobic surface and the sustained-releasing antibacterial activity of the MSMAs, resulting in an excellent antibacterial activity, and the antibacterial activity against E. coli can reach up to99.3%.

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