Silicone oil, also known as silicone or polydimethylsiloxane, refers to polydimethylsiloxane and its derivatives. It belongs to high molecular weight polymers and is a type of non greasy synthetic oil and wax. In cosmetics, it is widely used as a high-quality oily raw material. It has excellent physical and chemical properties.

After further reaction, some methyl groups in the polydimethylsiloxane of silicone oil are replaced by carbon functional groups, special organic groups, or polyether segments, which can produce various modified silicone oils. Modified silicone oil retains the high and low temperature resistance, hydrophobicity, and physiological inertness of polydimethylsiloxane, while endowing it with new properties such as compatibility with organic polymers, solubility in water and alcohol, ease of emulsification, lubricity, softness, adsorption, and superior surface activity.

Nowadays, silicone oil can be almost applied to various cosmetics, and cosmetics containing silicone oil have the following characteristics:

（1） Good lubrication performance, can form a uniform waterproof and breathable protective film after applying to the skin, but without any sticky or greasy feeling, with good luster;

（2） Good resistance to ultraviolet radiation. It does not undergo oxidative degradation under ultraviolet light, which can cause skin irritation;

（3） Good anti-static properties. Experiments have shown that applying skincare cream containing silicone oil completely eliminates static electricity on the skin and has a significant dust removal effect;

（4） Good breathability, even if a silicone oil film is formed on the skin, it does not affect the discharge of sweat. At the same time, it has a slow release and fragrance fixing effect on essence, so the fragrance preservation period is longer;

（5） Good stability, chemically inert, with no adverse effects on other components of cosmetics, especially active ingredients, and good compatibility;

（6） Non toxic, odorless, tasteless, and will not cause irritation or allergies to the skin.

According to the structure of silicone oil and its application in cosmetics, silicone oil can be divided into the following categories:
（1） Dimethicone
（2） Cyclomethicone or volatile silicone oil (Dm)
（3） Dimethicone copolymer or water-soluble silicone oil
（4） Amino silicone oil
（5） Polymethylphenylsiloxane (Phenyldimethylsiloxane)
（6） Emulsified silicone oil
（7） Silicon wax
（8） Silicone grease and silicone paste
（9） Long chain alkyl silicone oil