Silicone oils are typically composed of linear polysiloxane compounds that orient in spiral chains. This unique structure enables the oils to effortlessly glide and slip over one another. Silicone oils possess remarkable thermal stability and can maintain their flexible and flowing properties even under extreme temperature conditions. The most commonly produced silicone polymer is polydimethylsiloxane.
However, variations can be achieved by incorporating additional organic groups such as phenyl, vinyl, epoxide, or amino into the siloxane polymer, which can confer specific characteristics or reactivity in certain cases.
Silicone Oil Molecular Structure
Silicone oils and other siloxane polymers have a repeating backbone that consists of alternating silicon and oxygen atoms. Silicone oils are composed of linear repeating chains in which silicon and oxygen alternate, with each silicon atom, typically bonded to two carbon-based substituents, commonly methyl groups. The degree of polymerization in silicone oils refers to the average number of repeating siloxane groups within a polymer chain, ranging from a few units to several thousand units.
By substituting a portion of the methyl groups with phenyl groups or amino functional groups, the interaction of siloxane polymers with other materials can be altered. Additionally, incorporating reactive organic groups into siloxane polymers enables their integration with various types of organic polymers, resulting in unique properties when compared to standard organic polymers.
The Properties of Silicones Oil
The viscosity of silicone oils can range from 0.65 (cs) to 2,000,000 cs, and their viscosity remains constant across a broad temperature range. When compared to certain organic polymers, silicone polymers exhibit impressive thermal stability, withstanding temperatures up to 250 °C. This stability can be attributed to the unique chemical bonds between silicon and oxygen within the polymer chain.
Silicones possess a remarkably low surface tension, allowing them to easily spread on surfaces, and they exhibit higher compressibility compared to hydrocarbon and mineral oils. Siloxane polymers demonstrate excellent dielectric properties and remarkable resistance to shear stress, natural aging, oxidation, and hydrolysis.
Use Silicone Oil
Silicone oils find wide application in everyday products. Particularly, let’s examine the role they play in enhancing the quality of your facial tissues. Thanks to the excellent soft hand feeling and good hydrophilicity of some types of siloxane polymers, top-grade facial tissues have been using silicone-type softeners to enhance the luxurious “soft feel” of high-quality facial tissues. By incorporating silicone oil as a softener, the tissues achieve a remarkable level of softness and a smooth, silk-like texture, while maintaining their strength.
Benefits of using silicone-based softeners include:
- Emulsions with excellent shear stability, make them suitable for various additive processes.
- Treated tissues exhibit good water absorption and permeability.
- Treated tissues retain their whiteness.
- Enhancement of the antistatic and antibacterial properties of the tissues.
Applications of Silicone Oils
Silicone oils are commonly utilized as lubricants, thermic fluid oils, or hydraulic fluids. They possess excellent electrical insulation properties and, unlike their carbon analogs, are non-flammable. These oils are widely employed in laboratories for heating baths (referred to as “oil baths”) placed on hotplate stirrers, as well as in freeze-dryers as refrigerants, owing to their temperature stability and efficient heat transfer characteristics.
Silicone oil is frequently used as the working fluid in dashpots, wet-type transformers, diffusion pumps, and oil-filled heaters. In the aerospace industry, it finds application in the external coolant loop and radiators of the International Space Station’s Zvezda module, where it dissipates heat in the vacuum of space.
A specific class of silicone oils known as cyclosiloxanes shares many properties with other non-cyclic siloxane liquids but exhibits relatively high volatility, making it useful in cosmetic products like antiperspirants.
Certain silicone oils, such as simethicone, are potent anti-foaming agents due to their low surface tension. They find industrial use in processes like distillation or fermentation, where excessive foam formation can cause issues. Additionally, they are added to cooking oils to prevent excessive foaming during deep frying. While silicone oils used as lubricants can unintentionally act as defoamers (contaminants) in processes where foam is desired, such as in the production of polyurethane foam.
Silicone oil serves as one of the primary ingredients in Silly Putty, along with boric acid.
When it comes to gun care, silicone oil proves to be ideal. It provides protection and lubrication for parts made of rubber, plastic, and metal. Due to its strong surface adhesion, the oil film remains in place for an extended period, making it suitable for the maintenance of CO2 guns and airsoft guns as well.
Medical Use
Silicone oil often finds application in consumer products with controlled flatulence. It has also been utilized as a substitute for vitreous fluid in the treatment of complex cases of retinal detachment, particularly those involving proliferative vitreoretinopathy, large retinal tears, and penetrating ocular trauma. Furthermore, silicone oil is employed in various medical and surgical procedures. Its water-repellent and lubricating properties make it suitable for maintaining surgical instruments. Additionally, silicone oil is utilized in digital rectal examinations (DRE) for medical purposes.
Automotive Use:
Silicone oil has commonly been used as the fluid in automobile cooling fan clutch assemblies and continues to be employed in newer electronic fan clutches.
To learn more about Silicone Oil, please contact A1 Silicones