Preparation And Characterization Of Oligo-and Polysilsesquioxanes:In-situ Octavinylsilsesquioxanes And Oligo-vinlysilesquioxane

Polyhedral oligomeric silsesquioxanes (POSS) have recently attracted more and more interest as building blocks for inorganic-organic hybrid materials, because of the unique structure. The POSS (T8, refered here) macromer is a well defined cluster with an inorganic silica-like core (Si8O12) surrounded by eight organic corner groups, compared with traditional nanocomposites and nanostructure hybrid materials.The most recent developments in this field concern the preparation of silsesquioxanes with liquid crystal properties, silsesquioxanes as building blocks of a three-dimensional structure and silsesquioxanes that mimic zeolite structures with an incompletely condensed structure (open cage).In present dissertation, a novel poly-vinly-silsesquioxanes (PVSQ) containing polyhedral oligomeric silswsquioxane molecules (POSS) were prepared by acid-catalyzed hydrolytic condensation of vinyltriethoxysilane (VTES). This polysilsesquioxanes were characterized by means of FT-IR, GPC,1H、13C、29Si NMR, a phase-contrast microscopy and wide-angle X-ray diffraction (WAXD). Hydrolytic reactions between water and VTES were set at the molar ratio of water to VTES of2:1,2:5and3:1, for investigating and controlling PVSQ structures as well as OctaVinyl POSS contents, and mechanistic and structural features of the reactions were discussed subsequently.Octa Vinyl POSS were precipitated from the PVSQ and characterized by1H、13C、29Si NMR, MALID-TOF, WXAD and single crystal diffraction. The cell and cluster of OctaVinyl POSS were investigated and simulated.The cohydrolytic polycondensations of phenytrictriethoxysilane or methyltrimethoxysilane and VTES were also conducted, as the controlled reaction provided oligo-and polysiloxanes with various structures. These might be potential as precursors to high performance silixon-based materials, which would be characterized by FT-IR and GPC preliminarily.