Tetraalkoxysilanes molecule

This is the first stage of the sol-gel process. A complete hydrolysis reaction of a tetraalkoxysilane molecule has the following form ... 

Bulk imprinting of metal oxide materials can be achieved by sol-gel co-condensation of alkoxides. If the template (orTSA) is attached to a polymerizable side chain (e.g., atriethoxysilanegroup) the co-condensation with tetraalkoxysilanes leads to a porous amorphous solid with covalently attached templates. The imprint molecule can finally be removed by chemical and/or physical means. 

The preparations and performance of molecular catalysts successfully heterogenized by physical entrapment for a wide range of reactions are reviewed in detail in [86,93]. Two synthetic protocols were used, depending on the chemical properties of entrapped molecules addition of dopant solution to prehydrolyzed Si(OR)4 at pH close to 7, or together with ammonium hydroxide to tetraalkoxysilane precondensed in acidic solution. Both, followed by gelation. 

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