Silicone oil is a kind of polyorganosiloxane with different degree of polymerization chain structure. It is obtained by hydrolyzing dimethyldichlorosilane with water to obtain an initial polycondensation ring body. The ring body is cracked and rectified to obtain a low ring body. A mixture of different degrees of polymerization can be obtained by removing low boilers by distillation under reduced pressure.

The most commonly used silicone oil, all organic groups are methyl, called methyl silicone oil. The organic group can also use other organic groups to replace part of the methyl group to improve certain properties of the silicone oil and apply to various uses. Common other groups are hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl and the like. In recent years, organo-modified silicone oil has developed rapidly, and many organo-modified silicone oils with special properties have appeared.

Silicone oil is generally colorless (or pale yellow), odorless, non-toxic, and non-volatile liquid. Silicone oil is insoluble in water, methanol, glycol and -ethoxyethanol, miscible with benzene, dimethyl ether, methyl ethyl ketone, carbon tetrachloride or kerosene, slightly soluble in acetone, dioxane, ethanol and alcohol . It has a small vapor pressure, high flash point and ignition point, and low freezing point. As the number of segments n is different, the molecular weight increases and the viscosity increases, so this silicone oil can have various viscosities, from 0.65 centistokes to millions of centistokes. If low-viscosity silicone oil is to be prepared, acid clay can be used as a catalyst for telomerization at a temperature of 180°C, or sulfuric acid is used as a catalyst for telomerization at low temperature to produce high-viscosity silicone oil or viscous material with alkaline catalyst.

Silicone oil is divided into methyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl hydrogen-containing silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil, methyl ethoxy silicone oil, methyl trifluoro silicone oil according to the chemical structure. Propyl silicone oil, methyl vinyl silicone oil, methyl hydroxy silicone oil, ethyl hydrogen-containing silicone oil, hydroxyl hydrogen-containing silicone oil, cyano-containing silicone oil, etc.; in terms of use, there are damping silicone oil, diffusion pump silicone oil, hydraulic oil, insulating oil , heat transfer oil, brake oil, etc.

Silicone oil has excellent heat resistance, electrical insulation, weather resistance, hydrophobicity, physiological inertness and small surface tension, in addition to low viscosity temperature coefficient, high compression resistance) some varieties also have radiation resistance performance.