Polyoxyethylene and polyoxypropylene block polymers are referred to as poloxamers. Several Poloxamers are known by the trade name PluronicR followed by a letter and number, either L, F, or P, which refers to liquid, flake, or paste physical forms, respectively. Poloxamer 407 is a polyoxyethylene polymer and a hydrophilic non-ionic surfactant. It is made up of two blocks of hydrophilic polyethylene glycol on either side of a central hydrophobic polypropylene glycol block. In cosmetic and personal products, poloxamer 407 is used as an emulsifier and solubilizer.
Origin
Poloxamers are typically formed under conditions of high pressure and temperature. An alkaline catalyst, like sodium or potassium hydroxide, is used to combine propylene oxide and ethylene oxide with propylene glycol. The neutral salt is neutralized, and the catalyst is no longer active.
Safety profile
The Cosmetic Ingredient Review (CIR) Expert Panel expressed concern regarding the possible presence of 1,4-dioxane, ethylene oxide, and propylene oxide as impurities. Ethylene oxide is highly volatile and a known human carcinogen. They stressed that the cosmetic industry should continue to use the necessary purification procedures to keep the levels below the established limits. The panel concluded that Poloxamer 407 is safe as a cosmetic ingredient in the practices of use and concentration.