Thickener aids amino acid surfactant systems

The consumer trend in recent years is for cleansing products that are mild, but also offer good cleansing and conditioning benefits to the skin. As a result, mild surfactants such as amino acid and amphoteric surfactants are being used more frequently to meet consumer requirements. Compared to traditional AES products however, these mild surfactants are difficult to use, hard to thicken, and often have stability problems. A new thickener, acrylates/beheneth-25 methacrylate copolymer (Novethix L-10 polymer), is an ideal choice as a thickener for these mild surfactant systems. In this study, Novethix L-10 polymer (now referred to as ‘the new thickener’) is added to different, commonly used amino acid surfactants, including sodium cocoyl glutamate, potassium cocoyl glycinate, and sodium cocoyl alaninate, all of which have different foaming and moisturising properties.1 Study results show that while it has very high thickening efficiency in traditional AES systems, the new thickener also works well in both pure amino acid surfactant systems and systems of amino acid surfactant combined with AES or other mild surfactants like alkyl polyglucoside (APG) or amphoacetates. The effects of pH, salt, and surfactant level in these systems were also studied. The new thickener can be used alone or combined with other thickeners to offer desired viscosity in difficult-to-thicken amino acid surfactant formulations, and also helps generate creamier, and more stable foam. The new thickener makes it possible to develop ideal, mild surfactant cleansing formulations.

 Materials

 Mild surfactants used for the study are three different types of amino acid surfactants: sodium cocoyl glutamate (Amisoft CS-22), sodium cocoyl alaninate (Amilite ACS-12), and potassium cocoyl glycinate (Amilite GCK-11). Other surfactants used are sodium lauroamphoacetate (Genagen LDA), decyl glucoside (Plantacare 2000UP). Rheology modifiers or thickeners for this study are acrylates/beheneth-25 methacrylate copolymer (the new thickener), and PEG-120 methyl glucose dioleate (Glucamate DOE-120 thickener). The new thickener is a hydrophobically modified alkali-swellable emulsion (Hyper- HASE) polymer which contains very high levels of hydrophobic modification in its structure, purposely designed to maximise its performance in surfactant systems. Glucamate DOE-120 thickener is a vegetable derived, highly efficient associative thickener designed for use with numerous anionic and amphoteric surfactant systems.