"Methyltris(trimethylsiloxy)silane (CAS 17928-28-8) is an organosilicon compound used as a catalyst, functional fluid, and building block in advanced silicone chemistry. Learn about its unique properties."
-Deshangchemical-chemechemi
Methyltris(trimethylsiloxy)silane, with CAS number 17928-28-8 and molecular formula C₁₀H₃₀O₃Si₄, is a distinctive Methyltris organosilicon compound featuring three trimethylsiloxy side groups. This compound, also known as tris(trimethylsiloxy)methylsilane, occupies a unique niche in silicone chemistry due to its high thermal stability, extreme hydrophobicity, and branched siloxane architecture.
Molecular Structure and Physical Data
Molecular Weight: 310.68 g/mol
Appearance: Colorless transparent liquid
Boiling Point: 192–193°C
Density: ~0.865 g/mL
Refractive Index: ~1.392
Flash Point: ~61°C
The branched architecture of this Methyltris compound — with a central Si–CH₃ core flanked by three –OSi(CH₃)₃ groups — creates a highly symmetric, sterically hindered molecule with exceptional chemical inertness.
Key Characteristics
Extreme Hydrophobicity
The nine methyl groups arranged around the silicon core create an exceptionally hydrophobic surface. This makes Methyltris(trimethylsiloxy)silane valuable as a release agent, water repellent additive, and hydrophobic modifier in coating formulations.
Thermal Stability
Compared to carbon-chain analogs, the Si–O backbone of this compound confers excellent stability at temperatures up to 200°C, enabling applications in high-temperature lubricants and dielectrics.
Low Surface Energy
The surface energy of films formed from this Methyltris compound rivals that of PTFE, making it attractive for anti-stick and anti-fouling surface treatments.
Applications
Catalyst and Catalyst Support
Methyltris(trimethylsiloxy)silane serves as a catalyst or catalyst support modifier in organometallic chemistry and Ziegler-Natta polymerization systems. Its ability to coordinate with metal centers without interfering with catalytic cycles makes it a preferred ligand spacer.
Silicone Fluid Additive
Added to polydimethylsiloxane (PDMS) fluids, CAS 17928-28-8 modifies viscosity, lubricity, and surface tension, producing specialty functional fluids for personal care and industrial lubrication.
Electronic Materials
The low dielectric constant and high thermal stability of this Methyltris compound are exploited in low-k dielectric films and encapsulation materials for semiconductor packaging.
Cosmetic Applications
Due to its excellent spreading characteristics, silky skin feel, and volatility profile, Methyltris(trimethylsiloxy)silane finds use in premium personal care formulations such as foundation primers, hair conditioners, and skin serums.
Comparison with Linear Silicones
Unlike linear PDMS or cyclosiloxanes (D4, D5), the branched Methyltris architecture provides distinct rheological behavior with lower viscosity at equivalent molecular weight, faster evaporation, and greater volatility — attributes that are specifically engineered for delivery and spreading applications.
Regulatory Status
Methyltris(trimethylsiloxy)silane is not currently listed as a SVHC (Substance of Very High Concern) under REACH. It is generally recognized as safe for cosmetic use at typical formulation levels. Consult current regulatory databases before use in food-contact or pharmaceutical applications.
