What it is
PEG-9 dimethicone is a silicone backbone modified with polyethylene glycol side chains, which gives it both oil-loving and water-loving character. This dual nature lets it act as an emulsifier that helps blend oil and water phases and stabilize them, especially in water-in-silicone or water-in-oil systems common in sunscreens. It also imparts a smooth, silky slip and helps disperse pigments and UV filters evenly.
Safety & warnings
PEG-9 dimethicone is generally well tolerated and is commonly used in leave-on products including sunscreens. As a silicone-based emulsifier it has a low irritation profile and is not a recognized fragrance allergen. As with other PEG-containing materials, cosmetic grades are purified to limit trace manufacturing impurities.
Origin & sourcing
Synthetic; made by attaching polyethylene glycol chains to a dimethicone (silicone) backbone.
Questions everyone asks
What does PEG-9 dimethicone do in a sunscreen?
It helps emulsify and stabilize the formula, keeping oil, water, and UV filters or pigments evenly mixed, while adding a smooth, silky feel.
Is it a silicone?
Yes, it is a silicone (dimethicone) that has been modified with PEG chains so it can also function as a water-compatible emulsifier.