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Study on the Synthesis and Properties of SiO2/TiO2-based Nanocomposite Materials

Author: LvYuJun
Tutor: LiChaoRong
School: Zhejiang University of Technology
Course: Applied Chemistry
Keywords: nanocomposites materials photocatalystic antibacterial hydrophobic
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Type: Master's thesis
Year: 2013
Downloads: 201
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Abstract


As a new material, nanocomposite materials have attracted a great deal of attention for theirunique physical and chemical properties and more extensive potential applications in variousfields. It is supposed to have important applications in catalysis, environmental protection,medicine and health, industrial production and so on. In this paper give a reviw of the researchprogress of the SiO2/TiO2nanocomposite materials in the application of photocatalystic,antibacterial, hydrophobic properties and preparation method. Based on the existing research, theorientation of the dissertation’s research and the program of the SiO2/TiO2nanocompositematerials were proposed. The main content and results achieved in this paper are summarized asfollows:1. As precursors which product by hydrolysis of tetrabutyl titanate, the silver-modifiedsponge-like TiO2porous materials have been prepared combine a hydrothermal process underdifferent reaction times, temperatures and proportion of the template agents. The morphologiesand structure and characteristic of as-prepared samples were analyzed by field emission scanningelectron microscopy （FESEM） and X-ray diffraction （XRD）. And the possible formationmechanism of silver-modified sponge-like TiO2porous materials was discussed. Results showthat polyvinylpyrrolidone （PVP） plays a key role in the formation of titanium dioxide arrays.Compare to the commercial P25（Degussa） and flower-like TiO2, the silver-modified sponge-liketitanium dioxide porous materials exhibit an obvious enhanced photocatalytic activity.2. The mesoporous SiO2supported silver antibacterial nanospheres have been successfullyfabricated by a sol-gel method. Firstly, the polyvinylpyrrolidone reduce the the Ag+to Ag core,then the SiO2shell were synthesised by St ber process, and etched by sodium hydroxide. Themorphologies and structure of as-prepared samples were analyzed by FE-SEM, transmissionelectron microscopy （TEM）, XRD and N2adsorption. The obtained antibacterial nanosphereswith the most diameters of100nm and the shell shows a mesoporous structure. The antibacterialeffects on Escherichia coli TG1by the obtained antibacterial nanospheres were systematicallyinvestigated by changing the content of antibacterial nanospheres and the cultivation time. Results show that this materials owned excellent antibacterial effects. Furthermore, theantibacterial nanospheres/PVA composite film were tested against two different mass percent ofbacteria–Escherichia coli （E. coli） and Staphylococcus aureus （S. aureus）, the results demonstratethat the antibacterial nanospheres could increase the antibacterial efficiency of the PVA film andexhibit a long-lasting antibacterial capability.3. PDMS surface was modified by different sizes of silica and commercial titania, the controlof the adjunction of silica or titania, achieve the requirements of hydrophobic materials withregard to hydrophobic material or low transmittance, and expand the properties of hydrophobicsurface materials, PDMS hydrophobic material were continuously adjustable from transparent toopacity.4. SiO2/TiO2Fe3O4magnetic nanocomposite materials have been prepared with hydrothermaland sol-gel processes. FE-SEM, XRD, vibrating sample magnetometer （VSM） had been used tocharacterize the morphology, structure and magnetic performance. Results show that theas-obtained sample own a wide distribution of particle size of the nanoparticles and the spinelphase. Contact Angle results confirmed the hydrophobic properties of the as-obtained samples,analysis the influence of hydrophobic on the surface roughness and surface free energy. Inaddition, we observed that the magnetic materials become needle shape when the powder onglass surface under the action of a magnetic field. The obtained samples exposed in the air for amonth and still maintain its excellent hydrophobic property. Since the sample has superhydrophobic and magnetic properties, it can be expected to be widely applied in medicalmachinery, steel anti-corrosion and so on.5. In our case, a glass slide spin-coated with SiO2nanoparticles, is held above the flame of aparaffin candle, deposition of a soot layer turns the surface of the substrate，forming a layer ofcarbon nanoparticles with irregular rough pore structure. SEM reveals that the soot consists ofcarbon particles with a typical diameter of30to40nm, forming a loose, fractal-like network.Due to the sample surface and SiO2basement formation of the micro-nano composite classstructure, thus showing better super hydrophobic.

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