Investigation Of Polysiloxane Microspheres And Their Functionalization

As a kind of novel functional material, polymer microspheres process many unique properties, such as surface properties, packing properties, magnetics properties, biology compatibility and modified with functional group. So they can be applied in many fields, such as standard for measurement, biomedicine, information, analytical chemistry and chromatogram. Recently, polymer microspheres modified with functional groups have been used in biology engineering, immunity inspection, electron technology, information industry, HPLC, etc. Hollow polymer microspheres have low density and high surface, and the hollow part can pack many object molecules. So they can be used in medicine releasing system, catalyst, architecture, photoelectricity material and chromatogram separation due to the enwrap effects. They also can be used as micro-reactor. Polysiloxane microspheres are fabricated by using polysiloxane. They not only have properties of polysiloxane, but also they show microsphere structure features. So they are expected as novel materials to have a wide application in the future. Now they have been used in rubber, plastics, cosmtics, coating and photical products. They can be used as additive, scatter particles, releasing agent and apparatus protection.In this thesis, the polysiloxane microspheres were prepared by using hydrolysis-condensation reactions from methyltriethoxysilane (MTES). The microspheres were characterized with infrared spectrum, transmission electron microscope (TEM) and scanning electron microscope (SEM), the results indicated that the particles were dispersed well without conglomeration and the microsphere size was in the range of 0.8 ～1.2um with narrow distribution. The influences of parameters, such as the concentration of MTES, the amount of water, catalysts, reaction temperature and the speed of stirring on the particles morphology and size distribution were investigated. A mechanism of polysiloxane microspheres growth was proposed: in the first period, small seed particles were formed from the hydrolysis-condensation product of MTES, then the subsequent hydrolysis-condensation product of MTES grew on the seeds to form polysiloxane microspheres.Hollow polysiloxane microspheres were prepared by hydrolysis-condensation reaction from methyltriethoxysilane (MTES) using a mixture of water and organic solvents. The hollow microspheres were characterized with infrared spectrum, transmission electron microscope (TEM) and scanning electron microscope (SEM). The results indicated that the particles were dispersed well and the microsphere size was in the range of 0.7 ～ 1.5um and the thickness of the shell was in the range of 150 ～ 300nm. The influences of reaction parameters such as the concentration of MTES, the amount of water, organic solvent, catalysts and the speed of stirring on the particles morphology and size distribution were investigated. A mechanism of hollow polysiloxane microspheres formation was presumed: organic solvents were dispersed as small particles in the water system. The product of MTES hydrolysis-condensation would form a shell around the small organic solvent particles. Methyl on silicon atom would dissolve in the organic solvent. The hydroxyl that comes from the hydrolysis of ethoxyl on silicon atom would dissolve in water outside. So a shell would form by condensation reaction of these hydroxyls catalyzed by base. The organic solvent particle is in the center. So hollow polysiloxane microspheres were formed.Rhodamine B (RhB) was introduced in polysiloxane microspheres and hollow polysiloxane microspheres. The micropheres were characterized by fluorescence speotrophotometer. The results indicated that the particles have photoluminescence phenomenon.