Synthesis And Properties Of Novel Organosilicone Monomers And Their Polymers

Silicone elastomers composed of polysiloxanes with side methyl group partly or fully substituted by aryl groups are currently functioned as the significant encapsulants for High-Brightness Light-Emitting Diode (HB LED) because of their high refractive index values. However, these materials are not stable against yellowing at the junction temperature of LED chips since the pheny group in the polymers is more susceptible to heating induced oxidation than the methyl group once lasting for longer periods. Although the discoloration of the phenyl polysiloxane materials could be alleviated by lowering the content of the phenyl group, unfortunately, their refractive index decreases significantly and thus lowering the efficiency of light extraction.To prepare silicone encapsulant materials with high refractive index and good anti-yellowing properties, the phenyl group in the side chain of polysiloxane backbone was replaced by other alicyclic or alkyl aromatic groups. Dichlorosilanes or dialkoxysilanes with high refractive index values were the basic monomers for fabricating polysiloxanes suitable to LED encapsulants. To avoid the yellowing discoloration caused by the phenyl functional groups, three kinds of tolyl group modified diethoxysilanes were synthesized through the Wurtz-Fittig coupling reaction. Since these three kinds of silanes were never reported, therefore, synthesis method and important properties of these compounds, such as the spectra properties(’H-NMR and13C NMR) and the physical properties (the density, the normal boiling point, the enthalpy of vaporization and the flash point) need to be investigated. This thesis was consisted of the following four chapters.In chapter one, the general methods for synthesis of organic silicon monomers, especially the methods for preparing phenyl modified silanes, were were briefly reviewed. The technical routes for synthesizing phenyl group modified silicone fluids were also introduced in this chapter. The study on Vapor-Liquid Equilibrium (VLE) for pure chemicals was also reviewed.In chapter two, o-, m-and p-tolylmethyldiethoxysilane were prepared by means(?) of the Wurtz-Fittig reaction initiated from methyltriethoxysilane, o-chlorotoluen(?) w-chlorotoluene or p-chlorotoluene. The orthogonal design method was used t(?) investigate the influences of various factors, such as the molar ratio between the lced stocks, the reaction temperature and the feeding time, on the yield of the final prdu The optimum conditions in the preparation of each kind of chemicals were deterimmed through the variance analysis. The synthesized chemicals were characterized by(?) GC-MS and NMR spectra, respectively.In chapter three, densities and the refractive index of three novel monomer(?) measured simultaneously by DMA4500&RXA170combined density and refract,(?) index instrument. The saturated temperature of o-DEMTS, m-DEMTS and p-DEM(?) at various pressures ranging from2.0to61.0kPa was determined by means of (?) inclined ebulliometer and their normal boiling points were measured according (?) Siwoloboff method. Both Clarke&Glew equation and Antoine equation exhibit(?) correlation between the model and experimental data. The critical parameters of(?) three isomers were estimated from the group contributions and group intracno(?) method.In chapter four, o-DEMTS,m-DEMTS and p-DEMTS were hydrolyzed to synthesize tolyl group modified silicone fluids through different methods. The tolyl group substituted silicone fluids were prepared when tetramethyl ammonium hydroxide was used as catalyst and end-capped with low viscosity silicone oils. S(?) terminated polysiloxane copolymers containing tolyl methyl siloxane segment w.(?) prepared under the catalysis of concentrated sulfuric acid and end-capped with1,3-dihydrogen-1,1,3,3-tetramethyldisiloxane. The synthesized polymers were analyzed by GPC and their thermal stabilities were primarily investigated by (?)...