Organosilicon materials can be classified into silane coupling agents (organosilicon chemical reagents), silicone oil (silicone grease, silicone emulsion, silicon surfactant), high temperature vulcanized silicone rubber, liquid silicone rubber, silicone resin, composite material and so on. 

Silicone is a kind of thermosetting plastics, one of its most outstanding properties is excellent thermal oxidation stability. After heating at 250 ℃ for 24 hours, the weight loss of silicone resin is only 2 ~ 8%. Another outstanding performance of silicone resin is its excellent electrical insulation performance, which can maintain its good insulation performance in a wide range of temperature and frequency. 
 
Silicone resin is a kind of semi inorganic polymer with silicon oxygen silicon as main chain and organic groups connected on silicon atoms. Polysiloxane with highly crosslinked network structure is a highly branched polymer (compared with linear silicone oil), which can be solidified into solid. It has the dual characteristics of organic resin and inorganic materials, and has unique physical and chemical properties. The properties of the final products depend on the amount of organic groups (i.e. the ratio of R to SI).  

The monomer for preparing silicone resin is chlorosilane, which can be alcoholized to obtain corresponding alkoxysilane. Because they are not corrosive, and have greater hydrolysis stability, easy preservation and easy separation than the corresponding chlorosilane, they are widely used monomer components. By changing the number of functional groups in monomers and choosing different substituents, polymers with different degrees of polymerization, branching and crosslinking can be prepared, and products with different properties can be obtained to adapt to different uses.

The amount of organic groups in silicone resin (R / Si value) is one of the main indexes to control the quality of silicone resin. The curing property, film flexibility, hardness, heat resistance and cracking resistance of silicone resin are related to R / Si. Generally, the R / Si ratio of linear silicone oil is slightly greater than 2, that of silicone rubber is close to 2, and that of silicone resin is about 1.0. The smaller the R / Si ratio is, the better the curing performance of silicone resin is, the smaller the thermal weight loss is, the harder the film is, but the flexibility is reduced, the film becomes brittle and the impact strength is reduced; The higher the R / Si ratio, the longer the curing time at high temperature (200-250 ℃) or with the help of drying agent, the better the flexibility, the lower the film hardness and the better the impact strength.  

In addition, the properties of silicone resin are closely related to the types of organic group R. when the organic group is - CH3, the silicone resin can be endowed with thermal stability, hydrophobicity, demoulding property and arc resistance; When the organic group is - C6H5, the oxidation stability of the silicone resin can be improved; When the organic group is - CH = CH2, the curing property of silicone resin can be improved and coupling property can be given; When the organic group is phenyl or ethyl, the blending property of silicone resin and organic compound can be improved; When the organic group is - NH2 (CH2), the water solubility of the polymer can be improved and the coupling property can be given; When the organic group is long chain alkyl, the hydrophobicity of silicone resin can be improved. Therefore, siloxane monomers with different groups can be selected to prepare silicone resin according to specific performance requirements.