OH-500 Hydroxy-Terminated Polydimethylsiloxane (PDMS)
Silico® OH-500 Hydroxy-Terminated Polydimethylsiloxane (PDMS), CAS Number 70131-67-8, is a linear silicone polymer featuring hydroxyl (-OH) groups at both termini. This structure imparts unique properties, making it suitable for various industrial applications.
Product Introduction:
Silico® OH-500 Hydroxy-Terminated Polydimethylsiloxane (PDMS), also known as silanol-terminated PDMS or α,ω-dihydroxypolydimethylsiloxane, is a linear silicone polymer capped with reactive hydroxyl (-OH) groups at both molecular ends. With the CAS Registry Number 70131-67-8, this silicone fluid is a vital intermediate for a broad range of silicone-based formulations and industrial applications.
Technical Data
| Property | Specification |
|---|---|
| Chemical Name | Hydroxy-Terminated Polydimethylsiloxane |
| Synonyms | Silanol-Terminated PDMS, α,ω-OH-Polydimethylsiloxane |
| CAS Number | 70131-67-8 |
| Molecular Structure | HO–(Si(CH₃)₂–O)ₙ–H |
| Appearance | Clear, colorless to slightly hazy viscous liquid |
| Viscosity Range (25 °C) | 100 cSt to 100,000+ cSt (adjustable by molecular weight) |
| Density (25 °C) | ~0.97 g/cm³ |
| Hydroxyl Content | Typically 0.3%–1.5%, depending on viscosity |
| Refractive Index (20 °C) | ~1.403–1.406 |
| Flash Point | >250 °C (closed cup) |
| Solubility | Insoluble in water, soluble in hydrocarbons and esters |
| Shelf Life | 12 months (under dry, ambient conditions) |
Functional Features and Chemical Advantages
Reactive terminal silanol groups enable crosslinking, condensation, and functional modification.
Exhibits outstanding thermal stability, dielectric properties, and flexibility.
Compatible with a wide range of inorganic fillers, catalysts, and silicone resins.
Acts as a key base polymer for RTV-1 and RTV-2 silicone rubbers, adhesives, and sealants.
Applications of Hydroxy-Terminated PDMS
Hydroxy-terminated silicone fluids are valued for their adaptability across a broad spectrum of industries. Common use cases include:
1. Silicone Elastomer Systems
Used as a base polymer for room-temperature vulcanizing (RTV) and high-consistency rubber (HCR) systems.
2. Industrial Sealants & Adhesives
Forms part of silicone sealants, caulks, and structural glues when crosslinked with silanes or condensation catalysts.
3. Cosmetic and Medical-Grade Formulations
Due to its purity and biocompatibility, it is used in skin-conditioning agents, wound care formulations, and prosthetics.
4. Release and Anti-Foam Coatings
Blended with resins or functional fluids to produce mold release agents, antifoams, and surface protectants.
5. Textile and Leather Treatment
Acts as a water-repellent softener for fabrics and leather goods, improving feel and flexibility.
6. Electronics and Electrical Insulation
Serves as a base fluid in potting compounds and coating systems to ensure long-term moisture and thermal resistance.
Packaging and Viscosity Grades
Hydroxy-Terminated PDMS is available in various molecular weights and viscosities:
| Grade | Typical Viscosity (cSt) | Applications |
|---|---|---|
| Low Viscosity | 100–1,000 | Surface treatments, emulsions |
| Medium Grade | 10,000–100,000 | RTV sealants, personal care |
| High Viscosity | 100,000–1,000,000+ | Elastomer bases, mechanical damping |
Packaging Options:
1 kg bottles for lab and R&D use
20 kg pails and 200 kg drums for industrial bulk applications
1000 kg IBC containers for large-scale production
All technical data provided is based on current knowledge and experience. Users must test product suitability for intended applications.
No warranties are expressed or implied. Silico® assumes no liability for incidental or consequential damages.
Jessica G.
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