| In recent years, metal nanoparticles has become a new hot spot of research on nano composite material field, because of its special properties (e.g. small size, large specific surface area and higher surface chemical efficiency and so on) in the preparation field of function materials, such as electromagnetism, optics, biological medicine and mechanical. Metal nanocomposite particles exhibit special optical, electrical, magnetic and mechanical performance, resulting from the obvious difference of different nanoparticles in nanometer materials system and the interaction between the various components in the nanometer range. The research of metal nanoparticles mainly include the properties of different structure, different particle content and the assembly of composite prepared with advanced performance and widely used materials. Therefore, the metal nanocomposite particles not only have the intrinsic properties of metal nanoparticles but also exhibit many new special performance, which solve the limited application of metal nanoparticles of single component that can not effectively work out the problem, due to its size and other factors, leading to its special performance can not effectively play out the problem. However, metal nanoparticles have a series of problems can not be ignored in the application process. For example, agglomerate easily, self-protection, weak antioxidant capacity and uneven dispersion of particles in the polymer substrate surface in the metal nanoparticles catalytic reaction process. The exposed shortcomings during the use of metal nanoparticles significantly reduce the specific surface area and catalytic efficiency, which stuck the superior performance of the particle itself. Therefore, it is very necessary to invent a new method to prepare stable functional metal nanocomposite materials. This research based on the PS template, polyvinylpyrrolidone (PVP) has been chosen as both the reducing agent and stabilizing agent in the system to form SPS@Ag composite microspheres. At the same time, with the use of "template method", [Ag(NH3)2]+ions on mesoporous silica nanorods were in-situ reduced to metallic Ag nanoparticles and protected by PVP to form SiO2@Ag nanocomposite rods. At the same time, some special properties of the two kinds of metal nanoparticles composite materials were deeply studied, such as catalyst for the reduction of organic dyes, antibacterial properties and SERS active substrates for detecting trace of organic compounds. Specifically, the research contents and results are as follows:(1) The monodisperse polystyrene (PS) spheres were synthesized via dispersion polymerization using 2,2-azobisisobutyronitrile (AIBN) as a initiator, polyvinylpyrrolidone (PVP) as a stabilizer and styrene as a monomer. Monodisperse sulfonated polystyrene (SPS) microspheres were prepared via the sulfonation reaction of the monodisperse PS microspheres in the concentrated sulfuric acid. Sulfonated PS microspheres as the template, With a fresh [Ag(NH3)2]+ aqueous solution added into the sulfonated polystyrene microspheres dispersion containing PVP, [Ag(NH3)2]+ ions were easily adsorbed onto the surfaces of the sulfonated polystyrene microspheres and were in-situ reduced to metallic Ag nanoparticles and protected by PVP to form SPS@Ag composite microspheres. In addition, the produced SPS@Ag composite microspheres can be used as as the surface-enhanced Raman spectroscopy (SERS) active substrates for detecting trace of Penicillin G sodium and Chloramphenicol, and as antibacterial agents against Escherichia coli and Staphylococcus aureus.(2) By the use of surfactant template method, in this approach, mesoporous silica nanorods are first synthesized by using Hexadecyltrimethyl-ammonium bromide (CTAB) and triblock copolymer Pluronic F127 as the binary templates in basic aqueous solutions at room temperature, and used as the active template matrices, and those surfactant molecules were then removed by heating the as-synthesized silica nanorods at reflux in the ethanol/hydrochloric acidic solution. Polyvinylpyrrolidone (PVP) has been chosen as both the reducing agent and stabilizing agent in the system, the positive-charged [Ag(NH3)2]+ ions were adsorbed onto the surfaces of mesoporous silica nanorods. And then, these [Ag(NH3)2]+ ions on mesoporous silica nanorods were in-situ reduced to metallic Ag nanoparticles and protected by PVP to form SiO2@Ag nanocomposite rods.Additionally, these SiO2@Ag nanocomposite rods produced by this facile method can be used as catalyst for the reduction of organic dyes, a model reaction that the reduction of Rhodamine B by KBH4 was chosen. SiO2@Ag nanocomposite rods were also used as the effective SERS-active substrates to investigate the detection of Penicillin G sodium and Chloramphenicol. |
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