Hydroxy silicone oil is an organosilicon compound with a unique chemical structure and excellent properties, playing a significant role in numerous fields.

Chemical Structure and Characteristics

The chemical name of hydroxy silicone oil is α,ω - dihydroxy polydimethylsiloxane. Its molecular structure consists of a main chain of repeating silicon - oxygen bonds, with methyl groups as side chains and hydroxyl groups at the ends, having the structural formula HO((CH₃)₂SiO)ₙH. It usually appears as a colorless, transparent, odorless, and tasteless oily liquid. It has good chemical stability and physiological inertness, is insoluble in water and ethanol, but soluble in organic solvents such as carbon tetrachloride, benzene, chloroform, ether, and toluene.
Hydroxy silicone oil has a wide viscosity range, from very low to tens of thousands of Pascal - seconds, and its hydroxyl content ranges from a few parts per ten thousand to over ten percent. It also features low surface tension, a small viscosity - temperature coefficient, high compressibility, and good water - repellent and moisture - proof properties, and can be used for a long time under conditions of - 50°C to + 250°C.

Preparation Methods

There are mainly several preparation methods for hydroxy silicone oil:

• Silane Hydrolysis Method: It is synthesized through the reaction of silane with water. Usually, sodium hydroxide or potassium hydroxide is dissolved in water to prepare a solution containing hydroxide ions, which then reacts with raw materials such as dimethyldichlorosilane to generate hydroxy silicone oil.
• Ring - opening Degradation Method: It is formed by the ring - opening and hydrolysis of octamethylcyclotetrasiloxane under the action of an acid or a base.
• Silicone Rubber Degradation Method: It is obtained by the degradation of silicone rubber in an autoclave with the addition of water and a base as a catalyst.
• High - molecular - weight Polydimethylsiloxane Degradation Method: It is obtained by the degradation of high - molecular - weight polydimethylsiloxane with the addition of water and catalyzed by potassium hydroxide in a high - pressure environment.

Application Fields

• Rubber Processing: Low - viscosity hydroxy silicone oil is an excellent structure - controlling agent in silicone rubber processing. It can replace diphenylsilanediol, simplify the process, and improve process performance. In the production of room - temperature vulcanized silicone rubber, medium - viscosity linear hydroxy - terminated polydimethylsiloxane such as IOTA 107 V5000 - V80000 is one of the important raw materials. It is widely used in markets such as construction silicone sealants, industrial adhesives, and mold rubbers, enabling these silicone rubber products to have good flexibility, weather resistance, and chemical stability.
• Fabric Finishing: Hydroxy silicone oil can be formulated into an emulsion for fabric finishing. It can significantly improve the softness, smoothness, and sewing performance of fabrics. At the same time, it endows fabrics with water - proof and water - repellent properties, making the fabrics more comfortable to wear and more durable.
• Leather and Paper Treatment: As a water - proof, softening, and anti - sticking treatment agent for leather and paper, hydroxy silicone oil can effectively improve the surface properties of these materials, enhancing their quality and service life. For example, medium - to - high - viscosity hydroxy silicone oil products can be used as the base rubber for paper anti - sticking agents. The cured film has a good anti - sticking effect and can be used for the treatment of label base paper, asphalt packaging paper, carton sealing tape base paper, decorative paper base paper, etc.
• Other Fields: In coatings, hydroxy silicone oil can improve the adhesion and wear resistance of the coating. In the electronics and electrical industry, it can be used as the main component of insulating paint or as a component of insulators. In the cosmetics industry, it is often used in emulsions, creams, and skin - care products to play a role in moisturizing and improving the application feel. In the automotive industry, it is used as a lubricant and preservative, effectively improving the durability of automotive components. In the biomedical field, its good biocompatibility gives it potential applications in medical devices, drug carriers, etc.