Design And Fabrication Of Novel Multifunctionalized Composite Materials With Core-shell Structure

Core-shell material is one kind of the composite materials with unique structure, which is assembled by coating one nanomaterial with another. These core-shell materials can make the researchers design, tailor and optimize the structure and properties of materials in the nano-scale. In addition, the composites with core-shell structure have many unique optical, electrical, magnetic, catalytic and other properties which are different from the one-component materials. Today, core-shell materials have attracted people's key attention and become the research hotspot in chemistry, physics, biology, materials science, and many other disciplines and cross-cutting areas. Because of the unique magnetic response, mangeitc materials are widely used in the area of separation and biomedicine.A series of novel multifunctionalized composite materisl with core-shell structure were prepared and characterized in this thesis, and the main studies are as following:1. In chapter 3, the superparamagnetic Fe3O4 microspheres with the diameter of ca. 300nm were prepared by the solvothermal method. After treated with chlorohydric acid, it was coated with aminopropyl-functionalized amorphous silica by the co-condensation of tetraethylorthosilicate (TEOS) andγ-aminopropyltriethoxysilane (APTES) through Stober modified method. FT-IR, elemental analysis and TEM were used to characterize the aminopropyl-functionalized silica-coated magnetic microspheres, and then they were first used as magnetic separation carriers for immobilization of penicillin G acylase (PGA). The results showed that the amino content of the carriers has a little influence on the apparent initial activity, while the immobilization method and the shell thickness have more obvious influence on the apparent initial activity. The immobilized PGA (IMPGA) obtained through covalent attachment almost has no leaching and can retain above 78% of activity after 10 consecutive operations and exhibits higher resistance to thermal stability. More interestingly, the silica-coated magnetic microspheres show high saturation magnetization and the obtained IMPGA can be separated quickly using an external magnetic field.2. In chapter 4, well-defined superparamagnetic Fe3O4/SiO2/Polyaniline (PANi) core-shell-shell microspheres with smooth surface were first synthesized though in-situ polymerization of aniline monomers in the ethanol dispersion containing Fe3O4/SiO2 core-shell micropsheres modified with poly(vinylpyrrolidone)(PVP). The rattle-type Fe3O4@PANi hollow microspheres with large cavity were obtained by selective etching the spacer layer SiO2 with NaOH solution. The superparamagnetic core-shell-shell microspheres and their rattle-type hollow microspheres were characterized by TEM, FT-IR, thermal analysis and magnetic measurement. We found that the lower polymerization temperature is a key factor for coating PANi on the surface of silica with well-defined core-shell-shell structure. After etching silica with NaOH solution, the outermost PANi layer keeps the hollow framework because of its rigidity. The influence of the concentration of aniline on the thickness of the outer PANi layer and the influence of the thickness of the spacer layer SiO2 on the cavity size of rattle-type Fe3O4@PANi hollow microspheres were also studied. The superparamagnetic rattle-type Fe3O4@PANi hollow microspheres with large cavity have potential applications in catalysis support, drug delivery and separation because of its good environmental stability, quick magnetic response and large cavity size. For example, gold nanoparticles were sucessfully loaded inside the cavities of the ratlle-type Fe3O4@PANi hollow microspheres.3. In chapter 5, the study was focused on the coating of polypyrrole(PPy) on the surface of amido-functionalized Fe3O4/SiO2 core-shell microspheres in water and ethanol system, respectively. The influence of various factors on the coating of PPy was also studied. The results showed that PPy can be coated on the surface of the amido-functionalized Fe3O4/SiO2 core-shell microspheres and formed well-defined Fe3O4/SiO2/PPy core-shell-shell microspheres in the ethanol system. Furthermore, the aminopropyl-functionalized Fe3O4/SiO2 core-shell microspheres and PVP modified Fe3O4/SiO2 core-shell microspheres were also used as templates for coating PPy.4. In chapter 6, wormhole-like SDBS-HCl co-doped polyaniline(PANi) was synthesized with hexahydrate iron trichloride(FeCl3·6H2O) and ammonium peroxydisulfate((NH4)2S2O8) as oxidation in the presence of sodium dodecyle benzene sulfonate(SDBS) and hydrochloric acid. The effect of oxidant on the formation mechanism and structure was firstly characterized by powder X-ray diffraction, transmission electron microscopic and FT-IR spectroscopy. These results showed that the amount of oxidant, the concentration of hydrochloric acid, the reaction temperature and the concentration of SDBS have influences on the structure and components of products when the FeCl3 are used as oxidant. In contrast, when the APS are used as oxidant, the reaction temperature, concentration of hydrochloric acid and concentration of SDBS have a little bit influences on the structure and component of products, only the amount of APS has obvious influence on the structure and components of products. Finally, the SDBS-HCl co-doped PANi was used as a precursor to prepare N-doped microporous carbon materials, the BET surface area is 1504m2·g-1 and microporous surface area is 1314 m2·g-1...