silicone

silicone, polymer in which atoms of silicon and oxygen alternate in a chain; various organic radicals, such as the methyl group, CH₃, are bound to the silicon atoms. Silicones, which are unusually stable at extreme temperatures (both high and low), may occur as liquids, rubbers, resins, or greases. Silicones are prepared from halides of organic silicon compounds by decomposition. Such compounds are chosen and used in mixtures that allow the desired molecular weight and degree of cross-linking to be obtained in the final polymer. Water repellent, chemically inert, and stable at extreme temperatures, silicones are used as protective coatings and electrical insulators and in caulk.

Implants consisting of silicone gel surrounded by hard silicone were used in reconstructive and cosmetic breast surgery until 1992. The safety of inserting silicone prostheses into the body was questioned in a large product-liability case involving breast implants, but an Institute of Medicine panel concluded in 1999 that there was no evidence linking such implants with cancer, autoimmune diseases, and other serious illnesses. The use of such silicone implants for reconstructive surgery and for cosmetic surgery has been again approved by the FDA since 1998 and 2006 respectively.

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silicone

 or polysiloxane

Any of a diverse class of polymers manufactured as fluids, resins, or elastomers. They are partially organic compounds, but, unlike most polymers, they have a backbone containing no carbon, composed instead of alternating silicon and oxygen atoms. In most silicones, two organic groups (see functional group), usually methyl or phenyl, are attached to each silicon atom. Silicones in general are exceptionally stable and inert. Silicone fluids are used in hydraulic fluids, emulsion-breaking compositions, and breast implants and as adhesives, lubricants, water repellents, and protective coatings. Silicone rubbers are used as electrical insulators in encapsulations, coatings, and varnishes; as gaskets and caulking material; in specialized tubing; as automobile engine components; as flexible windows in face masks and air locks; for laminating glass cloth; and as surgical membranes and implants.

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A material that is used to make lubricants, sealants, adhesives, gels, coatings and breast implants. Silicone (pronounced "sill-uh-cone") is different than silicon (pronounced "sill-uh-cuhn"), which is used in semiconductors. Silicone is a compound of silicon and other materials, while silicon is pure silicon. See silicon.