Cetyl PEG/PPG-10/1 dimethicone is a type of silicone. Silicones have a long history of use in skin care products, beginning in the 1950s. They are well-known to improve the feel, appearance, and performance of products. Silicones provide an exceptionally desirable skin-feel that is dry and non-greasy, yet silky smooth. They also function as delivery agents for other ingredients, as well as improve product spreadability.
Dimethicone, also known as polydimethylsiloxane, is comprised of organic (carbon-based) groups attached to a linear inorganic backbone of silicon and oxygen. Based on this structure, dimethicone is considered to be a hydrophobic (lipid soluble) oil. One way to make dimethicone more water-soluble is by adding multiple units of ethylene glycol and/or propylene glycol to sites along the polymer chain. The oxygen atoms add polarity to the silicone and are readily available for association with water molecules. The number after PEG/PPG corresponds to the number of repeat units of PEG, followed by the number of PPG that have been added to dimethicone. The “cetyl” in the name of this ingredient indicates that it is a copolymer of cetyl dimethicone and an alkoxylated derivative of dimethicone.