When it comes to silicone oil, I believe that many friends, especially those who have not touched it, do not know what silicone oil is. But in fact, with the continuous development of society and the continuous progress of science and technology, the application scope and fields of silicone oil can be said to be numerous. For example, in life, we usually use facial cleansers, perfume, etc., which all contain silicone oil; In industry, it can produce lubricant, hydraulic oil, etc; For another example, in scientific research, it can be used as some aviation, cutting-edge technology, and even some military materials.

1、 Overview of silicone oil
Silicone oil is a kind of polyorganosiloxane with chain structure of different polymerization degree. It is prepared by hydrolysis of dimethyldichlorosilane with water to obtain a primary polycondensation ring. The ring is cracked and rectified to obtain a low ring. Then the ring, capping agent and catalyst are put together for polymerization to obtain mixtures with different polymerization degrees. Silicon oil can be prepared by removing the low boiling matter through vacuum distillation. The most commonly used silicone oil, all organic groups are methyl, is called methyl silicone oil. Organic groups can also use other organic groups to replace part of methyl groups to improve certain properties of silicone oil and apply to various purposes. Other common groups are hydrogen, ethyl, phenyl, chlorophenyl, trifluoropropyl, etc. In recent years, organic modified silicone oil has been developed rapidly, and many organic modified silicone oils with special properties have emerged. Now let's take a look at the types of silicone oil according to its chemical structure.

2、 Type of silicone oil

1. Dimethyl silicone oil, methyl silicone oil, polydimethylsiloxane
01 Nature:
It is also called methyl silicone oil. The main chain of the molecule is composed of silicon oxygen atoms, and the side group connected with silicon is methyl.
The viscosity at 25 ℃ ranges from 10 to 200 000 mm2/s.
The relative density ranges from 0.930 to 0.975.
The refractive index ranges from 1.390 to 1.410.
Colorless transparent, non-toxic and odorless oil.
It has excellent electrical insulation and heat resistance, high flash point, low freezing point, and can be used for a long time in the temperature range of - 50~+200 ℃.
The viscosity temperature coefficient is small, the compressibility is large, the surface tension is small, the hydrophobicity and moisture resistance are good, and the specific heat capacity and thermal conductivity are small.
It can be prepared by the telomerization of dimethylcyclosiloxane and hexamethyldisiloxane in the presence of catalyst.
The viscosity increases with the increase of the number n of silicon oxygen chains in the molecule, from the liquid that is easy to flow to the thick semi-solid.
It has excellent electrical insulation and heat resistance.
02 Application field
Plastic and rubber molding processing and food production as a long-term release agent.
It can also be used as high and low temperature lubricant between various materials.
Additives for manufacturing internally lubricated plastics.
The glass, ceramics, metal, cement and other products treated with dimethyl silicone oil are not only hydrophobic, but also corrosion resistant, mildew resistant and smooth.
Chemical, pharmaceutical, food and other departments are widely used as heat carriers and efficient defoamers.
It is used as shockproof damping material in precision machinery and instruments.
Electrical and electronic industries are used as high-temperature resistant dielectric liquids.
It is also widely used as polishing agent for leather of automobiles, furniture and floors, and as hydraulic oil for pumps, brakes, cylinders, etc.

2. Diethyl siloxane
01 Nature:
The main chain of the molecule is composed of silicon and oxygen atoms, and the side group connected with silicon is ethyl.
The viscosity range at 20 ℃ is 8 ～ 160 000 mm2/s, and the relative density is 0.95 ～ 1.06.
Colorless transparent, non-toxic and odorless oil.
The performance is similar to that of dimethyl silicone oil, but the high temperature resistance and oxidation resistance are slightly poor. The low temperature resistance and lubrication are better than that of dimethyl silicone oil. The long-term service temperature is - 70~+150 ℃.
It has good waterproof performance, chemical corrosion resistance, low viscosity temperature coefficient, low vapor pressure, high compressibility, low surface tension and other characteristics, and can be miscible with mineral lubricating oil.
It is prepared by co hydrolysis condensation and catalytic equilibrium of diethyl diethyloxysilane and triethyl ethoxysilane.
02 Application:
It has better lubrication performance than dimethyl silicone oil, and is widely used for lubrication of various precision instruments, precision mechanical equipment, speed measuring machines, synchronous motors, general instruments, clocks, shafts and various friction components.
It is used as release agent in food industry, plastic processing, rubber products and metal casting.
It can also be used for shockproof bearings of air flow meters, ammeters and speedometers to eliminate pointer chatter. Capacitors filled or impregnated with it have extremely stable working characteristics and are ideal liquid insulating materials.
In addition, it can also be used as defoamer, waterproof agent and polishing agent.

3. Phenylmethyl siloxane
01 Nature:
Its scientific name is polymethylphenyl siloxane liquid.
Colorless or yellowish transparent liquid.
The density is 1.0l~1.08g/cm3.
The refractive index is 1.425 ～ 1.533, and the surface tension is about 2.1 × 10-4～2.85 × 10-4N/cm。 Physical properties vary with molecular weight.
The density and refractive index increase with the increase of phenyl content.
The freezing point of low phenyl content is below - 70 ℃. The thermal stability of medium and high phenyl content is improved, and it has excellent radiation resistance.
non-toxic.
The gel time in 250 ℃ hot air is 1750h, and it also has good radiation resistance, high oxidation stability, heat resistance, flame resistance, UV resistance and chemical resistance.
It can be prepared from the hydrolysates of octamethylcyclotetrasiloxane, dimethyltetraphenyldisiloxane and methylphenyldiethoxysilane by telomerization in the presence of catalyst.
02 Field of application:
It is widely used as the base material of hair and cream cosmetics. It has strong film forming ability, less irritation to skin and eyes, and is safe for human body. It can be used as facial mask film forming agent and hair conditioner.
Because of its excellent radiation resistance, it is also widely used in skin care and sunscreen cosmetics such as sunscreen.
It is used as the carrier of lubricating oil, heat exchange fluid, insulating oil, gas liquid chromatography, etc.
It is used for insulation, lubrication, damping, shockproof, dustproof and high temperature heat carrier. It is an ideal liquid damping dielectric fluid for electronic instruments.

4. Methyl hydrosilicone oil
01 Nature:
Colorless transparent oil, viscosity is generally (1-5) × 10-2Pa · s, relative density 0.98 ～ 1.10, refractive index 1.390 ～ 1.410, hydrogen content 0.8% ～ 1.4%.
Under the action of alcohol alkali, the Si-H bond breaks and hydrogen is released.
Under the action of platinum catalyst, Si-H bond can be added to alkenes.
When the temperature is higher than 50 ℃, it can react with the compound containing epoxy group and has good film forming performance.
It can be prepared by co hydrolysis and condensation of methyl dichlorosilane and trimethylchlorosilane.
02 Application:
It can be used as waterproof treatment agent, release agent for rubber and plastic industry, and anti adhesion agent for paper and packaging materials.

For silicone oil, please check the details:
https://www.siliconerubbers.net/product-methyl-low-hydrogen-silicone-oil-my203.html