Polydimethylsiloxane (PDMS)

CAS Number:

63148-62-9

Chemical / IUPAC Name:

Polydimethylsiloxane (PDMS)

INCI Name:

Dimethicone

Molecular Formula:

 (C2H6OSi)n (linear polymer with trimethylsiloxy end groups)

Other Names:

Silicone oil 201-5cst, Dimethyl silicone fluid, Dimethylpolysiloxane, Methyl silicone oil

Uses:

201-5cst is an ultra-low viscosity, linear polydimethylsiloxane fluid. It is one of the thinnest and most fluid silicone oils available, offering exceptional spreading properties and a very light, non-greasy feel. Due to its low viscosity (5 centistokes), it acts as a volatile carrier in some applications and provides excellent surface wetting .

· Cosmetics & Personal Care: Used in hair sprays, facial cleansers, moisturizers, lotions, bath polishes, nail polishes, antiperspirants, and deodorants . It makes the skin feel soft, smooth, and delicate with no greasy feeling . It provides skin lubricity and excellent spreadability without leaving a heavy residue .

· Hair Care: Used in shampoos and conditioners to improve wet and dry combing, add shine, and reduce frizz without weighing hair down .

· Industrial Applications:

  · Release Agent: Used in rubber, plastic, and metal die-casting for non-carbonizing mold release .

  · Lubricant: Provides excellent lubrication for most plastic and elastomer surfaces .

  · Surface Treatment: Used for waterproofing and improving the feel of textiles, leather, and glass .

  · Defoamer: Effective in controlling foam in non-aqueous systems .

  · Polishes: Used in automotive and furniture polishes for high gloss and durable water-resistant films .

Origin

201-5cst is a synthetic polymer derived from silica (sand/quartz). It is manufactured through the hydrolysis and polymerization of dimethyldichlorosilane .

What does 201-5cst Silicone Oil do in a formulation?

• Emollient / Skin Conditioning Agent: Provides a soft, smooth, non-greasy feel to skin .
• Spreading Agent: Has very low surface tension and high spreadability, allowing even distribution of other ingredients .
• Volatile Carrier: At this ultra-low viscosity, it has higher volatility than thicker silicone oils, helping to deliver active ingredients quickly .
• Lubricant: Reduces friction on skin, hair, and industrial surfaces .
• Water Repellent: Forms a breathable, hydrophobic barrier on treated surfaces .

Safety Profile (Critical):

· General Hazard Classification: Considered non-toxic, non-irritating, and physiologically harmless . However, low viscosity grades (<5 cSt) are flammable. 201-5cst has a flash point of ≥120°C , making it combustible but not as highly flammable as lower molecular weight solvents .

· Safety Assessment: Recognized as safe for topical use in cosmetics by major regulatory bodies like the Cosmetic Ingredient Review (CIR) .

· Irritation & Sensitization: Generally regarded as non-irritating and non-sensitizing to skin. May cause short-term, transient eye irritation upon direct contact .

· Handling Precautions: Keep away from strong acids, alkalis, and Lewis acids, as they can cause degradation . Store in a cool, dry, well-ventilated place away from fire and direct sunlight .

· Shelf Life: Typically 24 months when stored properly in sealed containers at room temperature .

· Regulatory Status: Transported as non-toxic and non-dangerous goods . Compliant for use in food-grade applications and cosmetics worldwide .

Technical profile: