I. Definition and Chemical Nature of Silicone Oil
Silicone oil in cosmetics typically exists as a "siloxane" ingredient, such as polydimethylsiloxane and cyclopentamethoxysiloxane. Its chemical nature is that of an organosilicon polymer containing silicon-oxygen bonds (Si-O-Si), belonging to the high molecular weight compound family. Silicone oil molecules have a stable structure, with the main chain consisting of alternating silicon and oxygen atoms. The side chains can be modified with different functional groups (such as methyl, phenyl, and amino groups), giving it diverse properties. In cosmetic ingredient lists, ingredients containing "silane" or "siloxane" belong to the silicone oil family.

II. Core Characteristics and Functions of Silicone Oil
Lubricity and Spreadability: Silicone oil forms a smooth film, reducing skin friction and improving the smoothness of product application. For example, adding silicone oil to high-end face creams can make the skin feel silky smooth.
Breathability and Water Resistance: The silicone oil film allows the skin to breathe while preventing moisture loss. It is commonly used in sunscreens, waterproof mascaras, and other products to prolong makeup wear. Stability and Safety: Silicone oils are chemically inert, do not readily react with other ingredients, and are non-toxic, non-irritating, and gentle on sensitive skin.
Optical Properties: Low-viscosity silicone oils can fill in fine lines on the skin and enhance shine; high-refractive-index silicone oils (such as phenyl silicone oil) can enhance hair shine.
Antistatic and Dust-Repellent Properties: Silicone oils can eliminate static electricity on the skin, reduce dust adsorption, and keep makeup clean.

III. Common Types of Silicone Oils in Cosmetics
Dimethyl Silicone Oil: The most basic type, used in face creams and lotions, providing a smooth feel.
Cyclic Polysiloxanes: Low viscosity, highly volatile, giving products quick-drying properties, commonly found in setting sprays and hairsprays.
Amino Silicone Oils: Repair damaged hair and enhance shine, often used in conditioners and hair masks.
Polyether Silicone Oils: Water-soluble silicone oils that stabilize emulsion systems, used in shampoos and shower gels.
Phenyl Silicone Oils: High refractive index, enhancing product shine, used in high-end skincare and makeup products.