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Tetramethyldivinyldisiloxane (abbreviated as V2 or vinyl-terminated disiloxane) is an important organosilicon compound with the molecular formula [(CH₃)₂C₂H₃Si]₂O and CAS number 2627-95-4. It is a colorless, transparent liquid with a boiling point of 133-139°C, a density of 0.818 g/cm³, and a refractive index of 1.4118-1.4123. It exhibits high chemical purity and reactivity.
The key structural feature of this compound is the presence of two vinyl groups (-CH=CH₂) at both ends, connected by a siloxane bond (Si-O-Si), making it a crucial crosslinker and end-capping agent in the synthesis of silicone polymers.
There are two primary methods for synthesizing tetramethyldivinyldisiloxane:
Preparation of vinylmagnesium chloride: Vinyl chloride (CH₂=CHCl) reacts with magnesium (Mg) in anhydrous ether to form vinylmagnesium chloride (CH₂=CHMgCl).
Silylation reaction: Vinylmagnesium chloride reacts with dimethyldichlorosilane ((CH₃)₂SiCl₂) to produce dimethylvinylchlorosilane ((CH₃)₂(C₂H₃)SiCl).
Hydrolysis and condensation: Two molecules of dimethylvinylchlorosilane undergo controlled hydrolysis and condensation to yield tetramethyldivinyldisiloxane.
Reaction of silicon powder with chloromethane/vinyl chloride: In the presence of a copper catalyst, silicon powder reacts with chloromethane (CH₃Cl) and vinyl chloride (C₂H₃Cl) to directly produce dimethylvinylchlorosilane.
Hydrolysis and condensation: Similar to the Grignard method, the final product is obtained.
Modern Process Optimization:
High-selectivity catalysts improve yield
Molecular distillation enhances purity (≥99.5%)
Continuous production reduces energy consumption
Due to its highly reactive vinyl groups, V2 plays a critical role in the synthesis of silicone polymers, primarily used in:
V2 acts as a crosslinker, undergoing hydrosilylation with hydrogen-containing silicone oil (HSiMe₂O[SiMe₂O]ₙSiMe₂H) in the presence of a platinum catalyst to form a three-dimensional crosslinked network, imparting excellent elasticity, heat resistance, and mechanical properties to the rubber.
Applications:
Medical-grade silicone rubber (implants, catheters, prosthetics)
Electronic encapsulation materials (LEDs, semiconductor packaging)
High-temperature silicone gaskets
V2 serves as an end-capping agent in the synthesis of vinyl silicone oils and resins, improving their thermal stability, flexibility, and processability.
Applications:
Heat-resistant coatings
Release agents (labels, adhesive tapes)
Defoamers (industrial and food-grade)
V2 adjusts the curing rate and mechanical properties of LSR, making it suitable for injection molding processes used in automotive seals, baby bottle nipples, and more.
V2-derived silicone compounds are used in cosmetics and skincare products to provide a silky feel and film-forming properties.
Applications:
Sunscreen (enhances water resistance)
Hair conditioners (repairs cuticles)
Makeup (improves longevity)
As silicone materials find increasing use in new energy, medical, and electronics industries, the demand for tetramethyldivinyldisiloxane will continue to grow. Future developments include:
✅ Green synthesis processes: Reducing byproducts and improving atom economy
✅ High-performance silicone materials: For flexible electronics, 5G communications, and other emerging fields
✅ Biomedical materials: Developing safer medical-grade silicone rubbers
Tetramethyldivinyldisiloxane (V2) is a crucial crosslinking agent in silicone chemistry, playing an indispensable role in silicone rubber, silicone oils, electronic encapsulation, and medical materials. With advancements in synthesis technology and expanding applications, V2 will continue to drive the development of high-performance silicone materials, meeting the demands of future technology and industry.
