Structures, properties and potential applications of Ormosils

Ormosils are organic-inorganic hybrid solids in which the organic component may be chemically bonded to a silica matrix. Somewhat similar to inorganic silicate glasses, the structure of the silica network can be modified by the presence of organic groups. The resulting properties of the Ormosils are then governed by the type and concentration of organics used. Examples are presented in which the mechanical, electrical and optical properties of selected Ormosils can be influenced by organic groups. For instance, small amounts of polydimethylsiloxane (PDMS) added to a solution of TEOS will give an Ormosil about ten times harder than the hardest organic polymer. Larger amounts of PDMS (20%) will now yield an Ormosil which is as rubbery as organic rubber. Ormosils in which the organic and inorganic constituents are covalently bound to each other are the focus of this critical review. The potential applications of such Ormosils are discussed.