Siwin-M121
Siwin
Siwin-M121
CAS.14513-34-9
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3-Methacryloxypropylmethyldimethoxysilane, designated Siwin-M121, is a methacrylate-functional silane coupling agent with a dimethoxy structure and a methyl group bonded directly to the silicon atom. Its molecular formula is C10H20O4Si with a molecular weight of 232.35 g/mol, and it carries the CAS number 14513-34-9. The compound acts as a molecular bridge between organic polymers and inorganic substrates through its dual-reactive structure.
The molecule contains a methacrylate group that participates in free-radical polymerization with organic resins, and two methoxy groups that hydrolyze and condense with inorganic surfaces. Compared with trimethoxy methacryloxy silanes, the dimethoxy structure of Siwin-M121 provides lower crosslinking density at the interface, which can result in improved flexibility in cured systems. This structural distinction suits applications requiring a balance between adhesion promotion and coating flexibility.
Product No. | Siwin-M121 |
Chemical Name | 3-Methacryloxypropylmethyldimethoxysilane |
CAS NO. | 14513-34-9 |
Formula | C10H20O4Si |
Appearance | Colorless to light yellow liquid |
Density (ρ20℃，g/cm³) | 1.0 |
Refractive Index | 1.433 |
Purity | ≥98% |
Boiling Point (750 mmHg) | 258℃ |
Molecular Weight | 232.35 |
Molecular Structure |  |
The product exhibits a flash point of approximately 108°C (closed cup) and is soluble in common organic solvents including methanol, ethanol, acetone, and toluene. It hydrolyzes in the presence of moisture, releasing methanol and forming silanol groups that subsequently condense. Purity is determined by gas chromatography (GC) analysis, with each batch accompanied by a Certificate of Analysis.
In glass fiber-reinforced composites, Siwin-M121 serves as a sizing agent component that improves the bond between glass fibers and unsaturated polyester or acrylic resin matrices. The treatment enhances mechanical properties of composite laminates, including flexural strength and interlaminar shear strength, particularly under wet conditions. It is also used in mineral-filled composite systems to improve dispersion and interfacial adhesion.
In acrylic-based coating formulations, Siwin-M121 functions as a copolymerizable adhesion promoter that grafts into the resin backbone during polymerization. This integration improves coating adhesion to glass, metal, and mineral substrates, and contributes to enhanced weather resistance and film hardness. In ink systems, the silane supports improved film hardness and gloss retention on printed surfaces.
When incorporated into acrylic-based adhesive and sealant formulations, Siwin-M121 improves bond strength to inorganic substrates and enhances durability of bonded assemblies under environmental exposure. In silane-crosslinked polyethylene compounds for wire and cable insulation, it acts as a crosslinking co-agent that contributes to gel content and mechanical strength of cured insulation, while supporting improved electrical properties including reduced dielectric constant.
Siwin-M121 is available in 210L iron drums (200 kg/drum) and 1000L IBC containers (1000 kg/container). Custom packaging can be arranged for commercial procurement orders with specific requirements. The product should be stored in tightly sealed containers at room temperature in a dry, shaded area, away from acids, alkalis, and ignition sources. Under proper storage conditions, the shelf life is 12 months from the date of manufacture.
Siwin-M121 is produced through a controlled synthesis process with batch-to-batch consistency monitored at each production stage. Each batch undergoes GC analysis for purity determination, along with tests for appearance, density, refractive index, and moisture content. The manufacturing facility maintains consistent production capacity to support enterprise customers with regular supply requirements. Technical support staff are available to assist business buyers with formulation questions and application development.
The primary difference is the number of hydrolyzable methoxy groups on the silicon atom. Dimethoxy silanes have two methoxy groups plus one methyl group, while trimethoxy silanes have three methoxy groups. This structural difference affects crosslinking density, with dimethoxy versions producing a more flexible interphase and trimethoxy versions providing higher crosslink density.
Typical addition levels range from 0.5% to 3.0% by weight of the total formulation, depending on the resin system, substrate type, and performance requirements. Optimal dosage should be determined through laboratory trials specific to each application.
Store in original, unopened containers in a cool, dry area away from direct sunlight and moisture. Keep containers tightly sealed when not in use. Once opened, use the contents promptly or maintain an inert gas blanket to prevent moisture ingress.
Siwin-M121 is not a one-to-one replacement for trimethoxy methacryloxy silanes due to structural differences in the silicon center. While both products provide methacrylate functionality and adhesion promotion, the dimethoxy structure results in different crosslinking behavior. Formulation adjustments may be necessary when switching between the two types.
Yes, technical support is available to assist business buyers with formulation optimization, compatibility assessment, and application troubleshooting. The support team can provide guidance on dosage levels, mixing procedures, and performance evaluation methods.
