Preparation And Investigation Of Properties Of Hollow Silica And Composite Nanoparticles

Hollow silica microspheres have great potential applications in many fields,such as controlled drug delivery and release,catalyst support,sensors,and so on, due to their special microstructure and unique physical and chemical properties. Here, hollow silica micropheres and metal@silica composites were prepared and characterizied. Their controlling release and antimicrobial behavior were investigated. The main scopes and results of this thesis are as below.(1) In the ethanol/NH4OH medium, the hollow SiO₂ microspheres were prepared by coating SiO₂ on the surface of the polyvinylpyrrolidone (PVP) functionalized polystyrene (PS) particles and dissolving PS particles simultaneously. Some effects were investigated, such as the concentration of TEOS, solution temperature and the type of catalyst, etc. The morphologies of hollow SiO₂ were investigated by transmission electron microscopy (TEM). The results show that the as-synthesized hollow silica nanospheres exhibite a uniform size, and dispersed well. At the same time, the sustained-release of water-soluble anti-hypertension captopril enclosed in hollow silica was investigated.(2) Hollow mesoporpous silica nanopheres were perpared by a facile one–pot method, and they have a mean diameter of 170 nm and a narrow particle size distrubrition. The hollow particles were characterized by TEM. Meanwhile, captopril was enclosed into the hollow mesoporpous silica and the release property was invesgated. Results indicate that the hollow mesoporpous silica have good release property.(3) Ag@SiO₂, AgBr@SiO₂ nanocomposites and silica coating of silver and silver bromide multicore composite nanoparticles were prepared by template/sol-gel method. Their morphology and structure were characterized by TEM, X-ray powder diffraction (XRD) and UV-vis spectra. Their antibacterial properties against S. aureus, P. aeruginosa and E. coli were tested, respectively. The composites had a high antibacterial effect and seletivity.(4) Micrometer flower-like Cu/PVP architectures were prepared by reduction of copper chloride with hydrazine using PVP capping agent. Effects of reaction temperature, the amounts of N2H4?H2O, the molar ratio of PVP to CuCl2 and molecular weight of PVP on their morphology were studied. Their morphology and structure were also examined by TEM, XRD and UV-vis. Their antibacterial activity was also studied. The results show that Cu/PVP architectures have excellent antibacterial properties.