| Hierarchical polymer/inorganic composite particles can be built via the deposition of inorganic particles such as nanosilica and/or nanosilver on the surface of polymer particles. Hierarchical composite particles shows a larger specific surface area than a simple inorganic or organic material and endows the composites with many new properties, which are widely applied in the fields, such as super-hydrophobic surface, antifouling coating, catalysis, molecular trace detection etc.In this dissertation, we have focused on the following threes topics:First, mechanism of raspberry composite microspheres via in-situ reaction and the morphologies control; second, the build of hierarchical PS/SiO2/Ag and the SERS substrates; and finally, we study the application of composite microspheres in the degradation of MB.The main contents of the research are as follows:1. It can be fabricated stable structure polystyrene/silica (PS/SiO2) nanocomposite microspheres by the acrylic acid-modified polystyrene (PS) as template microspheres in the condition of different alkali catalyst in-situ hydrolysis of tetraethyl orthosilicate (TEOS). It is well known that silica and PAA-functional PS microspheres all shows negative charge at base environment, and they cannot form a stable composite microspheres due to the electrostatic repulsion effect. Here we introduce amine as the catalyst and raspberry-like PS/SiO2can be obtained easily. We proposed that the formation is based on the weak acid-base interaction (COO-/N+/-SiO-). The morphology, thermal stability, surface electrical properties and hydrophobic of composite microspheres are characterized by transmission electron microscopy (TEM), thermogravimetry (TG), zeta potential (ξ), contact angle. Results show that the structure of composite microspheres can be easily controlled by varying the amounts of PS templates, volume of alcohol-water ratio, type and amounts of catalyst et al. The PS/SiO2composite microspheres with a berry-like shape or core-shell structure are well controlled. 2. Hierarchical structure of polystyrene/silica/silver (PS/SiO2/Ag) composite microspheres can be prepared by in-situ chemical reduction of silver nitrate on the surface of PS/SiO2composite microspheres. One-pot and step-by-step template method were used to prepare PS/SiO2/Ag nanocomposite microspheres. The morphologies and effect on the R6G SERS enhancement were studied. TEM, TG, X-Ray powder diffraction (XRD), Ultraviolet-Visible (UV-VIS) spectroscopy, and Raman spectroscopy are used to characterize the morphology, thermal stability, and spectroscopic properties. The results show that the silver nanoparticles’shape and size can be easily controlled by adjusting template amount (PS or PS/SiO2), the concentration of silver nitrate, and reducing reagents. At the same time, to avoid the agglomeration of silver nanoparticles, dispersed stabilizer PVP was added. SERS enhancement of PS/SiO2/Ag prepared with berry-like PS/SiO2templates is stronger than that prepared with core-shell PS/SiO2templates. SERS enhancement is optimal when the size of nanocrystalline silver particles is16.8nm.3. PS/SiO2/Ag composite microspheres are used to catalyze the degradation of MB to simulate the waste water treatment. Several factors such as the amounts of catalyst, pH, and light source intensity are discussed. The degradation ratio is characterized by UV-VIS. The results show that the degradation of MB is enhanced with the increase of catalyst amount, pH value (pH>7) and intensity of irradiation source in visible region. By calculating the relationship between the rate of MB degradation and the irradiation time, it is found that the kinetic equation of photo-induced degradation of MB fitted first order linear relation. |
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