01.03.23
Given its effectiveness in improving the skin’s overall appearance, vitamin C is easily one of the most popular skin care ingredients on the market today.
A powerful antioxidant that defends against environmental stressors including UV damage, vitamin C also reduces the visibility of pigmentation caused from inflammation, and it’s shown to increase collagen, which improves skin firmness and elasticity.
Whereas L-ascorbic acid is water soluble and is the purest form of Vitamin C, the downside of working with ascorbic acid is that it starts to degrade and oxidize in the presence of water, oxygen and light where much of the actives efficacy is lost within a short period of time. For formulators, this presents a multitude of challenges and limitations when formulating water-based serums, lotions and creams.
To propel this trend in Vitamin C cosmetics applications forward while improving stability and sensorial benefits, Shin-Etsu Silicones of America recently introduced its Shin-Etsu Formulation Design (SFD) 10% anhydrous silicone serum system at the Society of Cosmetic Chemists’ 76th Annual Scientific Meeting & Showcase.
Shin-Etsu demonstated how its formulation CAL16-60 stabilizes 10% ascorbic acid in a non-aqueous emulsion (polyol in oil) with desirable sensorial aesthetic benefits.
Vitamin C Problem / Silicone Solution
One way to minimize ascorbic acid degradation is to make a non-aqueous emulsion using a polar solvent such as polyol instead of water to solubilize ascorbic acid. However, this can have a negative impact on the sensorial characteristics leaving the formula feeling heavy, greasy and shiny with a noticeable tack. The unique characteristics of silicone fluids and elastomer gels can drastically improve the feel of these systems, but stabilizing the formula under such acidic conditions can be a challenge. Oil bleeding and drastic drop in viscosity can occur over time.
Shin-Etsu’s new Formulation CAL16-60 system combines three key ingredients to create an ideal sensory feeling in a 10% vitamin C serum which is stable−with no oil separation, even at elevated temperatures, said the company. It represents Shin-Etsu's commitment to markets demanding vitamin C’s advanced benefits and includes the following key products/materials:
- KF-6105: Lauryl Polyglyceryl-3 Polydimethylsiloxyethyl Dimethicone Dimethicone (&)
- KSG-710: Dimethicone/Polyglycerin-3 Crosspolymer Dimethicone (&) Vinyl
- USG-1010: Dimethicone/Dimethicone Crosspolymer
After more than two years of research and over 70 test trials, Shin-Etsu discovered that its unique polyglycerin modified cross-linked and alkyl branched emulsifiers created a stable formula with superior sensorial effects. The KF-6105 is the main emulsifier and most critical in providing stability in emulsifying. The KSG-710 is the co-emulsifier and significantly improved the formula’s stability with a lighter skin feel.
The aesthetics of the formula were further enhanced by incorporating a lighter feeling elastomer gel in a volatile diluent−USG-1010. The newest ingredient in the formulation, the USG-1010, helped Shin-Etsu get over the hump of the sensory challenges and further stabilized the system. The final formulation is an opaque lotion that has a non- greasy, velvety texture that absorbs quickly with a powdery non-tacky after-feel, said the company.