Hydrosilation polymerization in supercritical carbon dioxide
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Supercritical carbon dioxide (ScC02) has a number of unique and beneficial properties that have been utilized in several polymerization reactions. This thesis comprises the novel approach of the formation of polysilanes and siloxanes via the hydrosilation reaction in ScC02. The research involved the synthesis of two new, fluorine-containing, vinyl-functonalized monomers: 1,3-bis(hexafluoro-2-propenyloxy-2-propyl) benzene and 1,3-bis[hexafluoro-2-(9- decenyloxy-2-propyl)] benzene. These monomers were chosen as coreactants with a series of commercially available dihydride-silanes/siloxanes, because polysiloxanes and fluoropolymers have been shown to be particularly soluble in ScC02. The polymerization was carried out in two solvents: ScC02 and the traditional organic solvent, benzene. The polymers were characterized by standard characterization techniques: solubility, nuclear magnetic resonance spectroscopy (NMR, proton and carbon), infrared spectroscopy (IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), water contact angle, and inherent viscosity.
The polymers showed good solubility in organic solvents. The polymers formed in ScCC>2 have as high or higher molecular weights than those obtained in organic solvent. Inherent viscosities were low, ranging from .02 to .05 dl_/g. The decyl polymers have lower glass transition temperatures, and are more thermally stable than propyl polymer. Water contact angles ranged from 60 to 90°.
CitationWelsch, R. L. (2000). Hydrosilation polymerization in supercritical carbon dioxide (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.
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