Surfactants – Cosmetic Uses in Cleansing and Skin Care

What Are Surfactants?

Surfactants are surface-active ingredients used extensively in cosmetic formulations. Their properties allow them to influence the interaction between water, oils, skin, and other formulation components.

Different surfactant classes can provide cleansing, emulsifying, foaming, conditioning, and refatting effects. Their chemical structure and charge also have a significant influence on skin feel and product performance.

Amphoteric Surfactants

Amphoteric surfactants are often derived from amino acids, and their net electrical charge varies according to the pH of the solution. Below their isoelectric point, they become positively charged and can therefore adsorb more readily onto the skin.

The length of the alkyl chain can also influence skin feel. Some C16/C18 betaines, for example, can provide a more greasy and refatting feel, although they may negatively affect foam performance.

Silicone-modified amphoteric surfactants can combine substantivity and refatting properties with the characteristic sensory profile of silicones.

Nonionic Surfactants

Some nonionic surfactants are valued for their emollient properties and pleasant afterfeel. Examples include sucrose esters, methyl glucose esters, and sucrose ethers.

Fatty acid alkanolamides are sometimes described as refatting agents. Although they are not lipids, they can provide a greasy, slippery feel to foam and contribute to the perception of a conditioned skin surface after cleansing.

Mild Anionic Surfactants

Several mild anionic surfactants can provide good skin feel in addition to their cleansing function. Examples include:

• Sarcosinates
• Taurates
• Acylglutamates
• Isethionates

Fatty acid–protein condensate salts can also act as conditioning aids, while the incorporation of fatty acids into soap and syndet bars can contribute to a creamier lather and improved skin feel.

Skin Feel and Afterfeel

The sensory properties of surfactants are not limited to their performance during cleansing. Some mild anionic and nonionic surfactants can provide a pleasant afterfeel, while their feel in aqueous solution may be perceived as rough or dragging.

The overall surfactant system therefore has an important influence on the sensory profile of a finished cosmetic product.

References

Handbook of Cosmetic Science and Technology – André O. Barel, Marc Paye, Howard I. Maibach.