silicone

/sil"i kohn'/, n. Chem.

any of a number of polymers containing alternate silicon and oxygen atoms, as (-Si-O-Si-O-)_n, whose properties are determined by the organic groups attached to the silicon atoms, and that are fluid, resinous, rubbery, extremely stable in high temperatures, and water-repellent: used as adhesives, lubricants, and hydraulic oils and in electrical insulation, cosmetics, etc.

[1905-10; SILIC(ON) + -ONE]

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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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▪ chemical compound

also called  Polysiloxane,  

      any of a diverse class of chemical polymers manufactured in the form of fluids, resins, or elastomers. Although they are partially organic in composition, the molecules of silicones differ from those of most polymers in that the backbone of their structure does not contain carbon, the characteristic element of organic compounds, but is a polysiloxane chain, in which atoms of silicon and oxygen alternate. In most members of the class, two organic groups, usually methyl (−CH₃) or phenyl (−C₆H₅), are attached to each silicon atom.

      Silicone fluids are exceptionally stable to decomposition by heat, water, or oxidizing agents and are good electrical insulators. They are used as components of hydraulic fluids and emulsion-breaking compositions and to impart water-repellency to textiles, paper, and many other substances.

      Silicone rubbers are valued for their electrical insulating properties, chemical stability, and the wide temperature range over which they retain resiliency. Silicone resins are used in protective coatings and electrically insulating varnishes and for laminating glass cloth. In the second half of the 20th century, silicone gels were used as breast (mammary gland) implants in women, though this application was curtailed in the early 1990s owing to its possible health risks.

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