Organosilicon, that is, an organosilicon compound, refers to a compound that contains Si-C bonds and at least one organic group is directly connected to the silicon atom. It is customary to use oxygen, sulfur, nitrogen, etc. to make the organic group and the silicon atom The connected compounds are also regarded as organosilicon compounds. Among them, polysiloxane composed of silicon-oxygen bond (-Si-O-Si-) is the largest, most researched and most widely used type of organosilicon compounds, accounting for about 90% of the total amount. the above.

 

Physical structure

The organic silicon material has a unique structure:

(1) Sufficient methyl groups on Si atoms shield the high-energy polysiloxane main chain;

(2) C-H has no polarity, which makes the intermolecular interaction force very weak;

(3) The Si-O bond length is longer, and the Si-O-Si bond angle is larger.

(4) Si-O bond is a covalent bond with 50% ionic bond characteristics (covalent bond has directionality, ionic bond has no directionality).

 

Features

      Due to the unique structure of organic silicon, it combines the properties of inorganic and organic materials. It has basic properties such as low surface tension, low viscosity-temperature coefficient, high compressibility, and high gas permeability. It also has high and low temperature resistance, electrical insulation, and oxidation resistance. Excellent properties such as resistance, weather resistance, flame retardancy, water repellency, corrosion resistance, non-toxic, tasteless, and physiological inertia, are widely used in aerospace, electronic and electrical, construction, transportation, chemical, textile, food, light industry, medical and other industries, Among them, silicone is mainly used in sealing, bonding, lubrication, coating, surface activity, mold release, defoaming, foam suppression, waterproofing, moisture-proof, inert filling, etc. With the continuous growth of the number and variety of silicones, the application areas continue to expand, forming an important product system unique in the field of new chemical materials. Many varieties are irreplaceable and indispensable for other chemicals.

      The metabolism of organisms also requires the participation of organosilicon, and the chemical formula of such organosilicon is usually CH3(SiOH)3. Silicone plays an important role in various functions of the body and is directly related to the absorption of minerals. The human body has an average of about seven grams of silicon, which far exceeds other important minerals such as iron. Iron and silicon are essential to the human body and are very important for maintaining normal metabolism.

      According to their different forms, silicone materials can be divided into: silane coupling agent (organosilicon chemical reagent), biologically active silicone, silicone oil (silicone grease, silicone emulsion, silicone surfactant), high-temperature vulcanized silicone rubber, liquid silicone Rubber, silicone resin, compound, etc.

 

characteristic

      The basic structural unit of organic silicon products is composed of silicon-oxygen chain links, and the side chains are connected to various other organic groups through silicon atoms. Therefore, the structure of organic silicon products contains both "organic groups" and "inorganic structures". This special composition and molecular structure make it integrate the characteristics of organic substances and the functions of inorganic substances. Compared with other polymer materials, the most outstanding properties of silicone products are:

1. Temperature resistance

       Silicone products are based on the silicon-oxygen (Si-O) bond as the main chain structure. The bond energy of C-C bond is 82.6 kcal/mole. The bond energy of Si-O bond is 121 kcal in silicone /Mole, so the thermal stability of organic silicon products is high, and the chemical bonds of molecules will not break or decompose under high temperature (or radiation exposure). Silicone is not only resistant to high temperatures, but also resistant to low temperatures, and can be used in a wide temperature range. Whether it is chemical properties or physical mechanical properties, the change with temperature is very small.

2. Weather resistance

       The main chain of organic silicon products is -Si-O-, there is no double bond, so it is not easy to be decomposed by ultraviolet light and ozone. Silicone has better thermal stability and radiation resistance and weather resistance than other polymer materials. The life span of silicone in natural environment can reach several decades.

3. Electrical insulation performance

       Silicone products have good electrical insulation properties. Their dielectric loss, voltage resistance, arc resistance, corona resistance, volume resistivity and surface resistivity are among the best in insulating materials, and their electrical properties are affected by temperature and frequency. The impact is very small. Therefore, they are a kind of stable electrical insulating materials, which are widely used in the electronics and electrical industries. In addition to excellent heat resistance, silicone also has excellent water repellency, which is a guarantee for high reliability of electrical equipment used in wet conditions.

4. Biological characteristics

        Biologically active silicone is an essential nutrient for the human body. Silicone is an important element that constitutes human tissue and participates in metabolism. It is stored in every cell of the human body, serving as a support for cell construction and helping other important substances such as magnesium, phosphorus, and calcium to be absorbed. The human body can only continuously obtain silicone through food.

5. Low surface tension and low surface energy

        The main chain of organosilicon is very flexible, and its intermolecular force is much weaker than that of hydrocarbons. Therefore, it has lower viscosity than hydrocarbons of the same molecular weight, weak surface tension, low surface energy and strong film-forming ability. This low surface tension and low surface energy are the main reasons for its various applications: hydrophobicity, defoaming, foam stability, anti-sticking, lubrication, glazing and other excellent properties.

 

use

        Because silicone has the above-mentioned excellent properties, its application range is very wide. It is not only used as a special material for aviation, cutting-edge technology, and military technology, but also used in various sectors of the national economy. Its application range has been expanded to: construction, electronic and electrical, textiles, automobiles, machinery, leather and paper, chemical and light industry, Metal and paint, medicine and medical treatment, etc.