Description

n-Octadecyldimethylmethoxysilane is a high-purity organosilicon coupling agent, also known as stearyl dimethyl methoxysilane. This compound is valued for its ability to modify inorganic surfaces, providing excellent hydrophobic properties and improved compatibility with organic polymers. It is essential for manufacturers in the coatings, plastics, and advanced materials sectors seeking to enhance product performance and durability.

Application

• Surface Modification Agent: Imparts water repellency and improves adhesion for fillers like silica, alumina, and glass fibers.
• Hydrophobic Coatings: A key intermediate in formulating water-resistant and anti-corrosion coatings for construction and automotive applications.
• Polymer Additive: Enhances dispersion and interfacial bonding of inorganic fillers within polyolefin, epoxy, and silicone rubber matrices.
• Adhesive & Sealant Formulation: Improves moisture resistance and long-term stability of high-performance adhesives and sealants.
• Nanomaterial Functionalization: Used to modify nanoparticles for use in composite materials and electronic applications.
• Textile & Leather Treatment: Provides durable water and stain repellency to fabrics and leather goods.

Basic Information

Product Name	n-Octadecyldimethylmethoxysilane
CAS No.	71808-65-6
Molecular Formula	C₂₁H₄₆O Si
Molecular Weight	342.68 g/mol
Synonyms	Stearyl dimethyl methoxysilane; Octadecyldimethylmethoxysilane; Dimethyloctadecylmethoxysilane; Methoxyoctadecyldimethylsilane; n-Stearyldimethylmethoxysilane; C18-silane; ODS; Long-chain alkyl silane coupling agent
EINECS	Contact for details

Quality Control

Our n-Octadecyldimethylmethoxysilane is manufactured under strict quality management systems. Every batch undergoes rigorous analytical testing, including gas chromatography (GC) and nuclear magnetic resonance (NMR), to ensure high purity and consistent performance. Certificates of Analysis (COA) detailing purity, identity, and key physical properties are provided with each shipment to support your quality assurance protocols.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). This product is hygroscopic (moisture-sensitive); containers must be kept tightly sealed to prevent degradation from atmospheric moisture.

Specification

Item	Specification
Appearance	Colorless to pale yellow clear liquid
Identification (IR)	Conforms to structure
Assay (GC)	≥ 97.0%
Refractive Index (n20/D)	1.440 - 1.445
Density (20°C)	0.85 - 0.87 g/mL
Moisture (KF)	≤ 0.5%

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