PCA Dimethicone is an isomer of the natural moisturizing factor "PCA" covalently bonded to a silicone backbone. It is designed for easy addition to leave-on and rinse-off conditioning and cleansing products.
The pyrrolidone carboxylic acid group greatly reduces the interfacial tension between water and silicone and has a very high affinity for keratin protein. This is because each PCA group holds several units of moisture and forms ionic bonds with any free amino group on the hair shaft.
The recommended formulation step is using this premix at about 5% level (as is) in a conditioner or shampoo. The end result is a product that is easier to formulate at lower temperatures and gives a higher degree of slip, volume and conditioning. Recommended pH range of the product is 4.5 to about 7 to maximize the slip properties.
PCA Dimethicone provides remarkable slip and shine properties observed during rinse off. The object of formulating this material is to retain and enhance these unique conditioning properties.
The mechanism is anionic and the hydrated silicone film is initially a layered (lamellar) system that leaves a hydrated film structure that refracts light in a focused manner, geometrically normal to the skin. The coefficient of friction is unusually low in the presence of water as the lamellar layers easily slide over each other. Therefore, conditioning on hair is very slippery until fully rinsed. The product was noted to add hair volume and styling ease. Cationic and quaternary conditioners may be used in combination with PCA Dimethicone to alter sensory properties after rinsing.