The most commonly used is polydimethylsiloxane, also known as dimethylsilicone oil.






It has low surface energy, low surface tension, low solubility and high activity in water and general oil. Its main chain is a silicon oxygen bond, which is a nonpolar molecule. It is not compatible with polar solvent water and general oil. It has low volatility, chemical inertness, stability and low toxicity.






Pure polydimethylsiloxane is difficult to be used as defoamer without dispersing. It may be due to its high interfacial tension with water and low spreading coefficient, which is not easy to disperse on the foaming medium. Therefore, the complex formed by mixing silicone oil with SiO2 aerosol, i.e. the hydrophobic SiO2 aerosol mixed with dimethylsilicone oil, can be prepared after a certain temperature and a certain time treatment.






Organosilicon defoamer is made of silicone grease, emulsifier, waterproof agent, thickener, etc. with appropriate amount of water by mechanical emulsification.






It is characterized by low surface tension, high surface activity, strong defoaming power, low consumption and low cost. It is immiscible with water and most organic matters, and can defoaming most bubble media. It has good thermal stability. It can be used in a wide temperature range of 5 ℃ - 150 ℃. It has good chemical stability and is difficult to react with other substances. It can be used in acid, alkali and salt solutions as long as it is properly configured, which will not damage the product quality;






It also has a physiological inert ld250g / kg mouse, which is usually used in the food and pharmaceutical industry. It has the functions of inhibiting and breaking bubbles for all bubble systems and belongs to the category of broad-spectrum defoamer.






It is widely used for defoaming in detergent, papermaking, pulp, sugar making, electroplating, chemical fertilizer, additives, wastewater treatment and other production processes.






In the petroleum industry, it is widely used in the desulfurization of natural gas to accelerate the separation of oil and gas;






It is also used to control or inhibit bubbles in the drying of glycol, extraction of aromatic hydrocarbon, processing of asphalt, dewaxing of lubricating oil and other devices.






In textile industry, it is used for defoaming in dyeing, refining and sizing;






In chemical industry, it is used for defoaming in synthetic resin, latex, coating, ink and other processes; in food industry, it is used for defoaming in various concentration, fermentation, distillation processes. The silicone grease can be applied on the wall, the outlet or on the metal net for defoaming. It can be used for defoaming in oil system. Silicone grease and low viscosity silicone oil can be used as water emulsion, which can be used for defoaming in various aqueous systems.






In medicine, it is usually used to remove the flatulence of organs or stomach organs before operation, X-ray and gastroscopy.