retinoic acid and folic acid, all of which are more stable and effective in a low pH environment.2,5 Low pH environments also play an important role in the effective stabilisation and improved performance of cationic emulsions. These are gaining market interest, due to their exceptional skin feel, their ability to improve moisturisation lev- els in mature skin, and their ability to form films on the skin. Formulating with cationic emulsifiers is not complicated, since similar techniques are used in traditional nonionic emulsifica- tion. The stabilisation of cationic emulsions is further achieved by incorporating viscosity enhancers, such as fatty alcohols, fatty acids and cationic compatible polymers.3,4 C a r bopol Aqua CC polymer offers many benefits for low pH emulsions in the range of 2-6. Unlike many other polymers, it has a high level of acid tolerance and broad emulsifier com- patibility, while providing emulsion stability and shear-thinning r h e o l o g y.
Testing efficiency The efficiency of Carbopol Aqua CC polymer in building vis- cosity and yield value by comparison with other rheology mod- ifiers used in low pH applications was tested using a gel screening