Preparation And Morphology Control Of Inorganic/Polymer Microspheres Via Miniemulsion Polymerization

Inorganic/polymer microspheres combine the advantages of polymer and inorganic substance, showing the unique character of electricity, magnetism, light, sound, etc. many research scholars have concerned its application in medicine, biotechnology and other aspects. In the beginning of the study, people paid more attention to the preparation methods、properties of core-shell composite microspheres and spherically symmetric structure. But, in recent years, preparation and application of non-spherically symmetric structures and non-core-shell structure composite microspheres caused the common concern of industry and the scientific community. This paper uses double in situ miniemulsion polymerization for preparing inorganic/polymer microspheres with different morphologies. Relative to conventional emulsion polymerization, miniemulsion polymerization is a relatively new method of latex particle size that can be controlled50-500nm, and the main nucleation way is the droplet nucleation which can greatly improve the coating of inorganic nanoparticles.In the first chapter, the preparation and morpholoresergy of inorganic/polymer composite microspheres were summarized and the research progress of non-core-shell structure and non-spherical symmetry were briefly introduced using the miniemulision preparation as the main line. In short, compared with other preparation methods, miniemulsion polymerization was more suitable for nanocomposite microspheres preparation.In the second chapter, the SiO2/PS composite microspheres were synthesized by double in situ miniemulsion polymerization with St, TEOS, DVB and HD as the major materials. This method was based on the in suit miniemulsion polymerization of organic monomers and in suit formation of silica from precursor (TEOS) within miniemulision monomers droplets simultaneous. In this work, different type of initiators and different TEOS contents were used to prepare composite microsphere. The results indicate that the type of initiator and the content of inorganic precursor TEOS have great influence on microsphere morphology. The PS/SiO2composite microsphere with the morphology of "Snowflake" was synthesized successfully by using CHPO/TEPA. However, using KPS or AIBN can only obtained "core-shell" structure composite microsphere.In the third chapter, the PS/SiO2composite microsphere was synthesized by double in situ miniemulsion polymerization with St, TEOS, DVB, MPS as major materials, then PS-PMMA composite microsphere was synthesized by using PS/SiO2composite microsphere as the seed and dropping the second monomer methacrylic acid (MMA). In this work, different type of initiators and emulsifiers were used to prepare PS-PMMA composite microsphere. The results indicate that different emulsifiers have different stabilizing effects, we discussed the anionic emulsifiers, cationic emulsifiers and non-ionic emulsifiers which have great influence on emulsion stability, and we find anionic emulsifier DB-45has good stability. Different types of initiators affect significantly on the morphologies and particle size of PS-PMMA composite microsphere,"three-tier"core-shell structure by CHPO/TEPA, larger diameter microcapsules structure by AIBN, non-spherical structure by KPS.In the fourth chapter, polystyrene microspheres with carboxyl and nitrile functional groups were prepared by miniemulsion polymerization with St, TEOS, DVB, AN, MAA as major materials, Ag+were adsorbed onto the surfaces of microspheres via electrostatic adsorption and reduced by dropping hydrazine hydrate. The obtained microspheres were characterized by TEM and X-ray diffraction, the results indicate that the particle size of microspheres with hollow structure was about500nm、the silver nanoparticles of which particle size was4rm were face centered cubic structure and have good disperse on the face of composite microspheres. The key of preparing silver nanoparticles/PS composite microspheres of antibacterial materials is the affinity of acrybnitrile on silver nanoparticles.