The basic structural unit of silicone products (that is, the main chain) is composed of silicon-oxygen chain links, and the side chain is connected to various other organic groups through silicon atoms. Therefore, the structure of silicone products contains both "organic groups" and "inorganic structure". This special composition and molecular structure make it integrate the characteristics of organic matter and the function of inorganic matter in one. It has many excellent properties such as high and low temperature resistance, climate aging resistance, electrical insulation, ozone resistance, water repellency, flame resistance, non-toxic corrosion and physiological inertia. Some varieties also have oil resistance, solvent resistance, radiation resistance. Compared with other polymer materials, the most outstanding properties of silicone products are temperature resistance, dielectric property, weather resistance, physiological inertia and low surface tension.
1. Temperature resistance characteristic
General polymer materials are mostly based on carbon-carbon (C-C) bond chain structure, such as plastics, rubber, chemical fibers, etc., and silicone products are based on silicon-oxygen (Si-O) bond chain structure, the bond energy of C-C bond 82.6 kcal/g molecule, Si-O bond energy in silicone is 121 kcal/g molecule. The silicone products have high thermal stability, and the chemical bonds of the molecules are not broken or decomposed at high temperatures (or radiation irradiation). Silicone is not only resistant to high temperature, but also low temperature, and can be used in a wide temperature range. Both chemical properties and physical and mechanical properties change little with temperature, which is also related to the fact that the molecules of organosilicon are flexible spiral structures.
2. Weather fastness
The main chain of silicone products is -SI-O -, and no double bonds exist, so it is not easy to be decomposed by ultraviolet light and ozone. In silicone products, the chain length of the Si-O bond is about one and a half times the chain length of the C-C bond. The long chain length gives silicone better thermal stability and radiation and weather resistance than other polymer materials. The service life of organic silicon in natural environment can reach several decades.
3. Electrical insulation property
Silicone products have good electrical insulation properties, and their dielectric loss, voltage resistance, arc resistance, corona resistance, volume resistivity and surface resistivity are among the best insulating materials, and their electrical properties are little affected by temperature and frequency. Therefore, they are a stable electrical insulation material and are widely used in the electronic and electrical industry. In addition to heat resistance, silicone also has excellent water resistance, which is the electrical equipment used in wet conditions with high performance.
4. Physiological inertia
Polysiloxanes are some of the most inactive compounds known. They are very resistant to biological aging, have no rejection reaction with the animal body, and have good anticoagulant properties.
5. Low surface tension and low surface energy
The main chain of silicone is very flexible, and this excellent flexibility is due to the basic geometric molecular configuration. Because the intermolecular force is much weaker than hydrocarbons, it has low viscosity, weak surface tension, small surface energy and strong film forming ability than hydrocarbons of the same molecular weight. This low surface tension and low surface energy is the main reason for its many applications: hydrophobic, defoaming, foam stabilization, anti-sticking, lubrication, glazing and other excellent properties.

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