Hexamethyldisiloxane

Product Details

CasNo： 107-46-0

MF： C6H18OSi2

Appearance： liquid

Delivery Time： 15 days

Packing： 200kg/drum

Purity： 99%

1. Basic Information

2. Physical Properties

HMDSO exhibits physical characteristics tailored for easy handling, rapid volatilization, and broad formulation compatibility:

• Appearance: Colorless, transparent liquid (no turbidity, sediment, or discoloration; visual clarity ensures low impurity levels).
• Density (20°C): 0.762–0.770 g/mL – significantly less dense than water, reducing transportation weight and enabling easy separation from aqueous phases.
• Melting Point: -59°C – remains liquid even in cold environments (e.g., winter storage), eliminating the need for heating to restore fluidity.
• Boiling Point: 99.5°C (at atmospheric pressure) – moderate boiling point, allowing quick evaporation during processing (e.g., semiconductor wafer drying) without requiring extreme heat.
• Flash Point (Closed Cup): -1°C – classified as a highly flammable liquid; strict fire prevention and electrostatic discharge control are mandatory.
• Refractive Index (n₂₀/D): 1.3748 – a consistent optical parameter used for rapid purity verification in quality control.
• Viscosity (20°C): ~0.65 cSt – extremely low viscosity, ensuring smooth flow, easy spraying, and uniform coating (critical for semiconductor wafer treatment).
• Vapor Pressure (20°C): ~5.33 kPa – high volatility, enabling rapid vaporization for applications like chemical vapor deposition (CVD) without residue.
• Solubility: Insoluble in water (solubility <0.001 g/100 mL at 20°C); fully miscible with organic solvents (ethanol, ether, acetone, xylene) and all common silicone fluids, supporting flexible formulation design.

3. Chemical Properties

Its stable molecular structure and controlled reactivity make it suitable for diverse industrial scenarios:

• High Chemical Inertness: The Si-O-Si backbone and non-polar methyl groups confer excellent stability under normal conditions. It does not react with water, weak acids, weak alkalis, or most organic/inorganic compounds, ensuring long-term shelf life (up to 24 months under proper storage).
• Thermal Stability: Stable at temperatures below 200°C; decomposes only at temperatures >300°C (producing low-toxicity siloxane oligomers and methane), making it compatible with high-temperature processes like semiconductor CVD (typically 400–500°C).
• Reactivity in Controlled Conditions:
  • Under strong acid catalysis (e.g., concentrated sulfuric acid), it can undergo cleavage of the Si-O-Si bond to generate trimethylchlorosilane (a raw material for other silicones).
  • In the presence of oxidizing agents (e.g., hydrogen peroxide) and catalysts, it can be oxidized to form silanol groups, enabling modification for specialty surfactants.
• Incompatibility: Reacts violently with strong oxidizers (e.g., potassium permanganate, chlorine gas) and strong bases (e.g., molten sodium hydroxide), which may trigger combustion or decomposition. Avoid mixing with these substances.

4. Quality Standards

To meet the strict requirements of downstream industries (especially semiconductors and high-end organosilicon synthesis), the product adheres to graded quality benchmarks:

Complies with international standards including China’s GB/T XXXX (organosilicon intermediates), ASTM DXXXX (US), and SEMI C12 (semiconductor material specifications).

5. Key Applications

HMDSO’s unique combination of inertness, volatility, and reactivity makes it indispensable across multiple high-value industries:

5.1 Organosilicon Synthesis (Foundational Use)

• Silicone Chain Terminator: As a "封头剂 (chain capper)" in the polymerization of silicones (e.g., silicone oils, silicone rubbers), it controls the molecular weight of polymers, improving their thermal stability (continuous use temperature increased by 20–30°C) and mechanical properties (tensile strength of silicone rubber enhanced by 15–20%).
• Precursor for Silicone Derivatives: Used to synthesize trimethylsilyl ethers (protective agents in pharmaceutical synthesis) and modified silicones (e.g., water-repellent resins for textiles).

5.2 Semiconductor Manufacturing (High-Value Application)

• Wafer Surface Hydrophobization: Prior to extreme ultraviolet (EUV) lithography, HMDSO vapor is deposited on silicon wafers to form a hydrophobic layer. This reduces adsorption of water vapor (a major cause of lithography defects) and lowers the defect rate of semiconductor chips by 30–40%.
• CVD Precursor for SiO₂ Films: Vaporized HMDSO reacts with oxygen in a CVD reactor at 400–500°C to form a nanoscale silicon dioxide (SiO₂) film (thickness: 10–100 nm). This film serves as an insulating layer or passivation layer for chips, with excellent thermal stability (>500°C) and dielectric properties.

5.3 Specialty Lubrication & Surface Treatment

• High-Speed Bearing Lubricant: Blended with perfluoropolyethers (PFPE), it forms lubricants for ultra-high-speed bearings (rotational speed >20,000 rpm) in aerospace and precision machinery. The blend reduces friction coefficient by 25–30% and extends bearing life by 50–80%.
• Marine Antifouling Coating Additive: Derivatized HMDSO (e.g., amino-modified) is added to marine coatings (0.5–1.2% dosage). It forms a low-surface-energy layer on ship hulls, reducing marine organism (barnacle, algae) adhesion by >95% and lowering fuel consumption by 5–8%.

5.4 Other Industrial Uses

• Analytical Chemistry: Serves as a stationary phase in gas chromatography (GC) for separating non-polar and weakly polar compounds (e.g., hydrocarbons, fatty acids).
• Surface Waterproofing: Applied to fiber fabrics (e.g., cotton, polyester) or electronic components (radio parts) to form a hydrophobic layer, improving moisture resistance and insulation.
• Solvent for Specialty Reactions: Used as a low-toxicity, high-volatility solvent in organic synthesis (e.g., pharmaceutical intermediate preparation), enabling easy solvent removal via distillation.

6. Packaging, Storage, and Transportation

6.1 Packaging

• Industrial Grade: Packaged in 200L galvanized iron drums or HDPE plastic drums (net weight: 150 kg/drum). The drums are lined with chemical-resistant liners to prevent corrosion and ensure airtightness.
• High-Purity/Semiconductor Grade: Packaged in 20L stainless steel buckets (for small batches) or 1000L ISO tanks with PTFE gaskets (for bulk supply), minimizing contamination from packaging materials.
• Small Batches/Laboratory Grade: Available in 1L/5L amber glass bottles (to avoid light-induced degradation, though HMDSO is not highly photosensitive) with leak-proof caps.

6.2 Storage

• Environmental Conditions: Store in a cool, dry, well-ventilated, fire-proof warehouse with a temperature range of 0–30°C. Avoid direct sunlight, high temperatures (e.g., near heaters), and humid environments (relative humidity <60%).
• Safety Measures:
  • Keep away from open flames, sparks, and ignition sources (e.g., uncertified electrical equipment). Install explosion-proof ventilation systems and electrostatic grounding devices.
  • Isolate from incompatible substances: strong oxidizers, strong bases, food, and pharmaceuticals.
  • Equip the storage area with fire-fighting equipment (dry chemical powder extinguishers, CO₂ extinguishers) and leak absorption materials (vermiculite, inert absorbent pads).
• Shelf Life: 24 months from the production date for industrial/high-purity grades; 18 months for semiconductor grade (due to stricter impurity control). Expired products must be re-tested for purity, moisture, and metallic impurities—if results meet standards, they can still be used.

6.3 Transportation

• Classified as a hazardous material (UN 1993) due to its flash point of -1°C. Comply with international/domestic regulations:
  • Maritime: Follow IMDG Code (stow in ventilated holds, away from heat sources and oxidizers).
  • Road/Rail: Use explosion-proof vehicles with electrostatic grounding; avoid rough handling to prevent drum damage.
  • Air: Restricted by IATA DGR (only allowed in limited quantities for laboratory use); bulk air transport is generally prohibited.

7. Safety and Regulatory Notes

• Toxicity: Low acute toxicity (oral LD₅₀ in rats: >5,000 mg/kg; inhalation LC₅₀ in rats: >8,000 ppm/4h). However, high-concentration vapor may cause mild respiratory irritation (e.g., coughing, dizziness); direct skin contact can lead to temporary degreasing (no long-term damage). Wear nitrile gloves, chemical goggles, and a vapor respirator (with organic vapor cartridges) during operation.
• Fire Hazard: Highly flammable; its vapor can form explosive mixtures with air (explosion limit: 1.1–6.0% by volume). In case of fire, use dry chemical powder or CO₂ extinguishers—do not use water, as HMDSO floats on water and may spread the fire.
• Regulatory Compliance:
  • EU: REACH-registered (No. 01-2119456243-42-XXXX) and compliant with SEMI standards for semiconductor materials.
  • US: Approved by the FDA for indirect food-contact materials (21 CFR §177.2600) and meets EPA inert ingredient requirements for industrial applications.
  • China: Conforms to national safety standards for hazardous chemicals (GB 12268) and semiconductor material specifications (GB/T 39560).