Search results
Results from the WOW.Com Content Network
An idealized equation is shown, in reality the silica produced is hydrated. This hydrolysis reaction is an example of a sol-gel process. The side product is ethanol. The reaction proceeds via a series of condensation reactions that convert the TEOS molecule into a mineral-like solid via the formation of Si-O-Si linkages.
Molecular structure of silicone hydrogel used in flexible, oxygen-permeable contact lenses. [62] The dominant material for contact lenses are acrylate-siloxane hydrogels. They have replaced hard contact lenses. One of their most attractive properties is oxygen permeability, which is required since the cornea lacks vasculature.
Silicone caulk can be used as a basic sealant against water and air penetration. In organosilicon and polymer chemistry, a silicone or polysiloxane is a polymer composed of repeating units of siloxane (−O−R 2 Si−O−SiR 2 −, where R = organic group). They are typically colorless oils or rubber-like substances. Silicones are used in ...
Silicone resin with R = CH 3, H or OH. Silicone resins are a type of silicone material which is formed by branched, cage-like oligosiloxanes with the general formula of R n SiX m O y, where R is a non-reactive substituent, usually methyl (Me = −CH 3) or phenyl (Ph = −C 6 H 5), and X is a functional group: hydrogen (−H), hydroxyl (−OH), chlorine (−Cl) or alkoxy (−O −).
The Stöber process is a well-studied example of polymerization of an alkoxide, specifically TEOS. The chemical formula for TEOS is given by Si(OC 2 H 5) 4, or Si(OR) 4, where the alkyl group R = C 2 H 5. Alkoxides are ideal chemical precursors for sol–gel synthesis because they react readily with water.
This page was last edited on 8 September 2019, at 23:48 (UTC).; Text is available under the Creative Commons Attribution-ShareAlike 4.0 License; additional terms may apply.
In organosilicon chemistry, a siloxane is an organic compound containing a functional group of two silicon atoms bound to an oxygen atom: Si−O−Si. The parent siloxanes include the oligomeric and polymeric hydrides with the formulae H[OSiH 2] n OH and [OSiH 2] n. [1]
Hydrogel. A mixture of acrylic acid, water, cross-linking agents and UV initiator chemicals are blended and placed either on a moving belt or in large tubs. The liquid mixture then goes into a "reactor" which is a long chamber with a series of strong UV lights. The UV radiation drives the polymerization and cross-linking reactions.