Description

Polymethyloctylsiloxane is a specialized organosilicon fluid characterized by its unique combination of a methylsiloxane backbone and pendant octyl groups. This structure provides exceptional lubricity, water repellency, and compatibility with a wide range of organic materials. It is a critical performance additive for formulators in the personal care, coatings, and industrial lubricant sectors seeking to enhance surface properties and reduce friction. The product is supplied under the identifier CAS NO 68440-90-4.

Application

• Personal Care & Cosmetics: Acts as an emollient and conditioning agent in skin creams, sunscreens, and hair care products, providing a smooth, non-greasy feel and improved water resistance.
• Release Agents & Mold Lubricants: Used in plastic, rubber, and composite manufacturing to facilitate easy demolding and prevent sticking.
• Industrial Lubricants & Greases: Serves as a base fluid or additive in specialty lubricants for high-temperature or plastic-contact applications due to its thermal stability and low volatility.
• Coatings & Inks: Imparts slip, mar resistance, and improved leveling in protective coatings, paints, and printing inks.
• Textile & Fiber Treatment: Applied as a softener and water-repellent finish for fabrics and non-wovens.
• Polishes & Waxes: Enhances gloss, durability, and water beading in automotive and furniture polish formulations.
• Plastic & Rubber Additive: Functions as an internal lubricant and processing aid to improve flow and surface finish during extrusion or molding.

Basic Information

Product Name	Polymethyloctylsiloxane
CAS No.	68440-90-4
Molecular Formula	(C8H18OSi)n • (CH4OSi)m
Molecular Weight	Varies by chain length (n, m)
Synonyms	Octylmethylsiloxane-dimethylsiloxane copolymer; Poly(methyloctylsiloxane); Methyl Octyl Silicone Fluid; PMOS; Silicone oil, methyloctyl; Polymethyloctylsiloxane fluid; Methyloctyl polysiloxane; Dow Corning® 2503 Fluid (example trade name)
EINECS	Contact for details

Quality Control

Our Polymethyloctylsiloxane is manufactured under a strict quality management system. Each batch undergoes comprehensive analytical testing to ensure consistent viscosity, purity, and performance characteristics. We provide full traceability and Certificates of Analysis (COA) are available upon request to support your quality assurance and regulatory compliance needs.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, well-ventilated area at room temperature (15-25°C). Keep away from strong oxidizing agents. Under these conditions, the product has an extended shelf life.

Specification

Item	Specification
Appearance	Clear, colorless to pale yellow liquid
Identification (IR)	Conforms to structure
Viscosity @ 25°C	Specification available upon request
Specific Gravity @ 25°C	0.87 - 0.92 (typical)
Refractive Index @ 25°C	1.40 - 1.43 (typical)
Purity (Assay)	> 98.0% (by GC)
Water Content	< 0.1% (by Karl Fischer)

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.