Synthesis and characterization of vinyl-bridged polysilsesquioxane sol-gel materials

Vinyl-bridged polysilsesquioxane gels were formed through the use of sol-gel polymerization methods. Acid- and base-catalyzed samples were prepared from both the pure cis-(1) and pure trans-(2) isomers of 1, 2-bis(triethoxysilyl)ethylene. Gelation times of the two isomers were compared. The trans monomer 2 formed gels within a week while the cis monomer 1 failed to gel even after several months. Gelation of 1 could be promoted by the addition of a coordinating metal such as palladium. The resulting cis- and trans- vinyl-bridged polysilsesquioxane gels were then processed either by vacuum drying to afford xerogels or by extracting with supercritical carbon dioxide to afford aerogels. These vinyl-bridged polysilsesquioxanes were characterized by SEM, nitrogen sorption porosimetry, solid state ²⁹Si and ¹³C NMR and x-ray powder diffraction.