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Formulas Deciphered: Facial Wash
By: Eric S. Abrutyn, TPC2 Advisors Ltd., Inc.
Posted: October 29, 2010, from the November 2010 issue of Cosmetics & Toiletries.
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Betaine often is formulated into facial cleansing products as a secondary surface active agent and a skin conditioning agent. Although its primary use is as a humectant and for foaming in hard or soft water, as stated, it also is used for its anti-static, hair conditioning and viscosity-controlling properties. The global personal care market formulates with betaine primarily in face/neck care, but also includes it in shampoo, skin care and shower products. Betaine can be used as an emulsifier and thickening agent in emulsions. It also has anti-septic properties and can be used in sanitizing products. A number of derivatives of betaine with similar properties have also enjoyed popularity in personal care formulations, such as cocoamidopropyl betaine, behenyl betaine, cetyl betaine, babassuamidopropyl betaine and coco-betaine. Derivatization of a simple betaine can improve mildness, modulate foam-boosting qualities and change the synergy with other surfactants.
Physical properties: Coco-betaine, shown in Figure 1, has a positively charged cationic functional group such as a quaternary ammonium or phosphonium cation. Therefore, coco-betaine can be considered a zwitterion.
When a cocamidopropyl constituent is attached to the coconut fatty acid, cocoamidopropyl betaine results, as shown in Figure 2. Cocamidopropyl betaine is derived from coconut oil and dimethylaminopropylamine, and its primary physical property is as a medium-strength surfactant.
Betaine is compatible with anionic, cationic and nonionic surfactant systems. It is an effective secondary surfactant used to enhance foam and viscosity. Betaine can replace cocamide DEA or MEA and has good water solubility within a wide pH range. It typically is formulated into personal care formulations at 29–33% w/w, oftentimes with 4–7% sodium chloride. Use levels of actives formulated with betaine vary based on application but are generally added at 0.5–3.0% into betain-containing formulations.
Finished Facial Cleansers
Following are two recent facial cleanser launches. The soothing facial cleanser represents a contemporary approach to mild, natural surfactants, and the overnight facial wash represents a more traditional surfactant system in a wide range of acne-cleansing products. The information presented here is taken from publicly available resources. The sample formulations provided are for illustrative purposes only and include estimated ingredient ranges to give formulators a starting point from which to build their own unique formulations.