Steareth-21 is a polyoxyethylene (PEG 21 moles) stearyl ether, a white solid that is almost colorless with a slightly waxy odor. It is a nonionic surface active agent used as an oil-in-water emulsifier with an HLB value of 15.5 for polar oil creams and lotions.
Steareth-21's performance capabilities are due to the superior emulsifying characteristics of stearyl alcohol as a lipophile and the unique distribution of ethylene oxide chain lengths. While originally designed for the emulsification of ceto-stearyl alcohols, its extraordinary versatility will be appreciated in the emulsification of oil-in-water-type products generally.
Numerous studies have proven that Steareth-21 blends are successful in emulsifying polar oils favored for their superior emollience, spreading, solvent, and carrier properties. However, they are challenging to formulate. These unusual properties are attributable to Steareth-21's particular ethylene-oxide distribution.
Providing exceptional emulsification for cetyl and stearyl alcohols, Steareth-21 exhibits tolerance to high levels of ethanol and a wide pH range in emulsions. It stabilizes antiperspirant emulsions based on Al Zr salts, produces a dense, rich aerosol foam, and creams with attractive surface gloss. It has excellent temperature stability, and a wide range of emollients can be formulated as the combination ratio is less critical than other emulsifiers.From the dermatological and ‘skin-feel’ points of view, polar oils usually offer better emolliency than mineral oils because ester-type oils are chemically much closer to the natural human skin sebum than mineral oils. Furthermore, polar oils offer better spreading on the skin and have better solvent and carrier properties.
However, pure polar oils are not easily emulsified. Combinations of Steareth-2 and Steareth-21 are well suited for polar oil-in-water-type emulsions as they have these advantages.
In combination with PPG-15 Stearyl Ether, it gives extra emolliency through the formation of liquid crystals. Steareth-21 is very effective with many materials that require emulsification, including cetyl, stearyl, and other fatty alcohols, and many widely used emollients, including isopropyl myristate, mineral oil, petrolatum, and others.
Steareth-21 is widely used as a general cosmetic ingredient in creams, lotions, aerosol products, antiperspirants, and many other types. Its nonionic nature enables it to be combined with other ingredients in almost all types of formulations and at a wide pH range.Related ingredients
