Preparation Of Polymer Latex Micro (small) Emulsion System And Inorganic Nanoparticles

Microemulsions have been used as novel chemical reactors for producing nanophase materials. In this thesis, firstly, we successfully carried out gamma-ray-induced microemulsion polymerizations with high monomer content by choosing high efficient surfactant system. Then, we prepared mesoporous cadmium sulfide nanoparticles using an oil-in-water microemulsion as template. We also conducted miniemuision polymerization of styrene using a polymerizable surfactant as sole stabilizer. The main results obtained in this dissertation are described as follows:1.γ-ray-induced microemulsion polymerization with high monomer content.(1)γ-ray-induced polymerization of butyl acrylate (BA) was performed in a microemulsion stabilized with a mixture of sodium of 12-acryIoxy-9-octadecenoic acid (AOA) and sodium dodecyl sulfate (SDS) in a weight ratio of 2 at room temperature. BA content in microemulsion can be successfully improved up to 40 wt % with low surfactant concentration (lower than 10 wt %). The resulted stable, translucent microlatexes contain particles with average diameter from 28.1 to 38.1 nm with different monomer content. Particle size decreases with the increase of dose rate and surfactant concentration. The maximum polymerization rate of BA in microemulsion irradiated by gamma ray increases with the increase of monomer concentration and absorbed dose rate.(2) Gamma-ray-induced polymerization of methyl methacrylate (MMA) was conducted in a microemulsion stabilized by a mixture of sodium salt of 12-acryloxy-9-octadecenoic acid and sodium dodecyl sulfate with various weight ratios at room temperature. The experimental data showed that the mixture of AOA and SDS with a weight ratio 2 was an efficient surfactant system for the microemulsion containing 38.6 wt% MMA and 5.5 wt% surfactant. The particle size of microlatex increases from 33.7 nm to 50.4 nm with the increase of weight ratio of MMA to surfactant in microemulsion from 4.05 to 7. Particle size decreases with the increase of dose rate. The study on kinetics indicates that the micellar nucleation plays an important effect on the microemulsion polymerization of methyl methacrylate. The polymerization rate increases with the increase of monomer content and absorbed dose rate.(3)γ-ray-induced copolymerization of butyl acrylate and acrylonitrile was performed in a microemulsion with high monomer content by using a mixture of sodium salt of 12-acryloxy-9-octadecenoic acid (AOA) and sodium dodecyl sulfate (SDS) in a weight ratio of 4 at room temperature. Monodisperse latex particles were obtained. IR and DSC results indicate that random copolymers are formed by microemulsion copolymerization and the value of glass transition temperature of the copolymers increase with the increase of the weight ratio of acrylonitrile in the feed.2. We carried out the in situ synthesis of stable crystalline mesoporous CdS semiconductor nanoparticles in the oil-in-water microemulsion composed of proper amount of OP-4, OP-10, cyclohexane, water and isopropyl alcohol while cadmium chloride and thioacetamide are used as reagent. The PL spectrum of CdS mesoporous nanoparticles at room temperature shows a broad emission band centered at～690 nm which is due to their surface states.3. Miniemulsion polymerization of styrene was performed by using a polymerizable surfactant (AOA) as sole stabilizer. The results of polymerization kinetics study confirmed the characteristics of miniemulsion polymerization. Monodisperse functionalized polystyrene latex were obtained.