Cyclomethicone is a volatile methyl siloxane which makes up a class of liquid silicones (cyclic polydimethylsiloxane polymers) that possess the characteristics of low viscosity and high volatility as well as being skin emollients and in certain circumstances useful cleaning solvents. Unlike dimethicones, which are linear siloxanes that do not evaporate, cyclomethicones are cyclic: both groups consist of a polymer featuring a monomer backbone of one silicon and two oxygen atoms bonded together, but instead of having a very long "linear" backbone surrounded by a series of methyl groups (which produces a clear, non-reactive, non-volatile liquid ranging from water-thin to taffy-thick), cyclomethicones have short backbones that make closed or nearly-closed rings or "cycles" with their methyl groups, giving them many of the same properties of dimethicones but making them much more volatile. They are used in many cosmetic products where eventual complete evaporation of the siloxane carrier fluid is desired. In this way they are useful for products like deodorants and antiperspirants which need to coat the skin but not remain tacky afterward. Most cyclomethicone is manufactured by Dow Corning.
- Barbara Kanegsberg; Edward Kanegsberg (2011). Handbook for Critical Cleaning: Cleaning agents and systems. CRC. p. 19. ISBN 978-1-4398-2827-4.
- Amarjit Sahota (25 November 2013). Sustainability: how the cosmetics industry is greening up. Wiley. p. 208. ISBN 978-1-118-67650-9.
- Meyer Rosen (23 September 2005). Delivery System Handbook for Personal Care and Cosmetic Products: Technology, Applications and Formulations. William Andrew. p. 693. ISBN 978-0-8155-1682-8.