Preparation Of Photosensitive Antibacterial SiO₂ Particles And Their Application In Coatings

With increasing requirements of antibacterial property in various fields,antibacterial coatings,which can kill or inhibit the bacteria on surfaces and keep the surfaces clean and hygienic,have attracted considerable attention.A conventional method for imparting coatings with antibacterial properties is based on releasing principle.Releasing antibacterial coatings lose the antibacterial ingredients too quickly and are unfriendly to the environment,becoming the main drawbacks of them.In the meanwhile,the antibacterial coating is susceptible to factors such as scrubbing and wear during use.And consequently,the antibacterial durability of coating is reduced.To work out these problems,UV-curable antibacterial agents with contacting principle are synthesized.And then,they are added into UV-curable coatings to get a series of contacting antibacterial coatings.1.The SiO₂-SH nanoparticles are obtained from a classical St?ber process with a thin layer of thiol groups on the particle surface.And the quaternary ammonium compound?QAC?with a terminal double bond is then further linked to particle surface through double bond and thiol group reaction to obtain SiO₂-SHx-QACy nanoparticles.After UV irradiation,photosensitive SiO₂-SHx-QACy has been crosslinked in the polyurethane coating.The effect of the different addition of SiO₂-SHx-QACy on curing kinetics,basic mechanical properties,and antibacterial properties of coatings is systematically investigated.SiO₂-SHx-QACy nanoparticles both show high levels of antibacterial properties toward Gram positive and Gram negative bacteria.And the coatings containing SiO₂-SHx-QACy nanoparticles show enhanced mechanical properties,such as coating hardness,scratch resistance,and heat resistance,and strong antibacterial activity.2.UV-curable fluoro-containing quaternary ammonium compound?QAC_F?is first synthesized by 1-bromo-1H,1H,2H,2H-perfluorononane?PFDB?and dimethylaminoethyl methacrylate?DMEAMA?.And then,QAC_F is linked to SiO₂-SH particle surface through double bond and thiol group reaction to obtain SiO₂-SHx-QAC_Fy nanoparticles.Add SiO₂-SHx-QAC_Fy to polyurethane resin formulation recipe.The migration behavior of the SiO₂-SHx-QAC_Fy in coatings is investigated.The mechanical properties and antibacterial properties of coatings are examined,and antibacterial property changes of coatings before and after wear are studied.The results show that the addition of the SiO₂-SHx-QAC_Fy nanoparticles in as less as 10 wt%in the formulation recipe would be enough to produce an antibacterial coating with excellent anti-wear resistance due to the self-migration of the modified silica nanoparticles.And SiO₂-SHx-QAC_Fy nanoparticles can migrate to the top surface of the coatings which enables the coating exhibit prominent antibacterial properties.Compared with coatings with mere antibacterial reagents,SiO₂-SHx-QAC_Fy added coatings show enhanced anti-wear property at very low particle additions.