- Silicone oil
Silicone oils (polymerized
siloxanes) are siliconanalogues of carbonbased organic compounds, and can form (relatively) long and complex molecules based on silicon rather than carbon. Chains are formed of alternating silicon- oxygenatoms (...Si-O-Si-O-Si...) or siloxane, rather than carbon atoms (...C-C-C-C...). Other species attach to the tetravalentsilicon atoms, not to the divalentoxygen atoms which are fully committed to forming the siloxanechain. A typical example is polydimethylsiloxane, where two methylgroups attach to each silicon atom to form (H3C) [SiO(CH3)2] nSi(CH3). The carbon analogue would be an alkane, e.g. dimethylpropane C5H12 or (H3C) [C(CH3)2] (CH3).
Silicone oils could be a basis for silicon-based organic life, but their more prosaic, primary uses are as
lubricantsor hydraulic fluids. They are excellent electrical insulatorsand, unlike their carbon analogues, are non flammable. Their temperature-stability and good heat-transfer characteristics make them widely used in laboratoriesfor heating baths ("oil baths") placed on top of hotplate stirrers. Silicone oil is also commonly used as working fluid in diffusion pumps.
Some silicone oils such as
simethiconeare potent anti-foaming agents. They are used in industrial applications such as distillationor fermentationwhere excessive amounts of foamcan be problematic. They are sometimes added to cooking oilsto prevent excessive frothing during deep frying. Consumer products to control flatus( antiflatulents) often contain silicone oil. Silicone oils used as lubricants can be inadvertent defoamers (contaminants) in processes where foam is desired, such as in the manufacture of polyurethanefoam. Silicone oils have been used as a vitreous fluidsubstitute to treat difficult case of retinal detachment, such as those complicated with proliferative vitreoretinopathy, giant retinal tears, and penetrating ocular trauma [cite journal | author=Martín-Gil J, Martín-Gil FJ, De Andrés Santos AI, Ramos-Sánchez MC, Barrio-Arredondo MT, Chebib-Abuchala N.| title=Thermal behaviour of medical grade silicone oils | journal=J Anal Appl Pyrolysis | year=1997 | pages=151–158| volume=42| doi=10.1016/S0165-2370(97)00002-8] . Silicone oil is also one of the two main ingredients in Silly Putty, along with boric acid. Silicone oil plays a useful role in gas powered airsoftguns where it is used to lubricate the rubber gas seals in gas blowback guns without degrading them as carbon-based oils would, as well as lubricating the moving parts of the guns.
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