Functionalized Silicic Esters for the Synthesis of Nonshrinking Sol-GelComposites

摘要

We, as well as others, have been interested in the sol-gel process for thesynthesis of hybrid inorganic/organic composite materials. Since our first report on the application of tetraalkoxysilanes possessing polymerizable alkoxides for the production of nonshrinking sol-gel composites, we have extended our efforts towards increasing the glass content in these composite materials. The stoichiometry in the tetraalkoxysilanes limits the maximum glass content in the original non-shrinking composites to 10-18%. In order to increase the glass content to greater than 50%, we focused our efforts toward the use of silicic acid oligomers. Molecular weights of the poly(silicic acid) materials have been varied from Mn = 5,000 to 2,000,000 by controlling reaction conditions. In addition, branching ratios (i.e., linear vs. spherical particles) can be controlled by changing the catalysts used. The properties of the resulting composite can range from a transparent flexible material to a transparent hard material simply by changing the organic polymer in the composite. Interpenetrating networks; organic-inorganic composites, sol-gel.