What Is Vinyl Fluorosilicone Oil?
Vinyl fluorosilicone oil, also known as vinyl-terminated fluorosilicone oil or vinyl-terminated polytrifluoropropylmethylsiloxane, is a reactive fluorosilicone oligomer with vinyl groups at the chain ends or along the side chains and trifluoropropyl groups introduced into the siloxane backbone. Compared with ordinary vinyl silicone oil, it retains the addition-cure reactivity of vinyl groups while offering better oil resistance, solvent resistance, chemical resistance and lower surface tension due to the trifluoropropyl structure. It is therefore widely used as a reactive base polymer for addition-cure liquid fluorosilicone rubber, fluorosilicone potting compounds, fluorosilicone release agents and oil-resistant coatings.
The product is usually a colorless or pale yellow transparent liquid. It can be transported as a non-dangerous chemical and should be stored away from acids, bases, oxidizing agents and moisture.
Key Technical Indicators
Vinyl Content
Vinyl content determines the ability of vinyl fluorosilicone oil to participate in hydrosilylation reactions. Common vinyl content is about 0.5%-1.5%, with some grades customizable according to formulation requirements. Higher vinyl content provides more crosslinking points, generally leading to higher hardness in the cured material, while tensile strength and tear strength may increase and then decrease depending on the formulation. Lower vinyl content is more suitable for systems requiring higher elongation, lower hardness or longer working time.
In addition-cure fluorosilicone rubber, vinyl content should be matched with the active hydrogen content of hydrogen-containing fluorosilicone oil by controlling the Si-Vi to Si-H molar ratio.
Viscosity
Vinyl fluorosilicone oil is available across a broad viscosity range, commonly from about 50 to 10000 mPa·s, with lower or higher viscosity grades also possible. Low-viscosity products offer good flowability and are suitable as reactive diluents, potting compound base materials and release agent components. Medium-to-high viscosity products have longer polymer chains, and cured elastomers usually show better tensile properties and resilience.
Oil and Solvent Resistance
The trifluoropropyl structure provides excellent resistance to fuels, engine oils, hydraulic fluids and non-polar solvents. When used as a base polymer in addition-cure fluorosilicone rubber, it can significantly improve volume stability in oil-based media and reduce swelling risk, making it suitable for automotive fuel systems, aerospace hydraulic systems and chemical sealing applications.
Flash Point and Thermal Stability
The flash point is typically above 260°C, with some higher-viscosity grades reaching 270-300°C or more. Volatility at 200°C/4h is usually below 5%, allowing stable performance across a wide temperature range and making it suitable for heat-resistant and aging-resistant fluorosilicone elastomer formulations.
Refractive Index and Surface Tension
Due to the fluorinated side chains, vinyl fluorosilicone oil has a relatively low refractive index and lower surface tension than ordinary methyl vinyl silicone oil. This makes it advantageous for release agents, defoamers, fabric finishing and antifouling coatings.
Appearance and Storage
The product is a colorless or pale yellow transparent liquid. It should be stored sealed in a cool, dry and ventilated place, away from acids, bases, oxidizing agents and substances containing active hydrogen.
Main Performance Features
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Reactive vinyl end groups: undergoes hydrosilylation with hydrogen-containing fluorosilicone oil under platinum catalysis to form a stable crosslinked network.
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Oil and solvent resistance: trifluoropropyl groups improve resistance to fuels, oils, hydraulic fluids and non-polar solvents.
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Wide-temperature performance: combines low-temperature elasticity of the siloxane backbone with heat and media resistance from fluorinated side chains.
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Customizable viscosity and vinyl content: can be tailored for liquid injection molding, potting, coating and release applications.
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Low surface tension: suitable for release agents, defoamers and surface treatment.
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Non-dangerous transport: convenient for sample delivery, bulk shipment and overseas customer trials.
Typical Application Scenarios
Base Polymer for Addition-Cure Liquid Fluorosilicone Rubber
Vinyl fluorosilicone oil is one of the main reactive base polymers for addition-cure liquid fluorosilicone rubber. Combined with hydrogen-containing fluorosilicone oil, platinum catalyst and reinforcing fillers, it can produce liquid fluorosilicone rubber with hardness around 30-60 Shore A. The cured material offers oil resistance, solvent resistance, wide-temperature performance and low compression set, suitable for automotive fuel system seals, sensor seals and aerospace sealing components.
Reactive Component for Fluorosilicone Potting Compounds
In fluorosilicone potting compounds, vinyl fluorosilicone oil serves as the vinyl-containing base polymer. Together with hydrogen-containing crosslinkers, it forms a dense crosslinked network, giving the potting material oil resistance, chemical resistance, electrical insulation and low-stress protection. Typical applications include automotive electronic modules, connectors, wire harness plugs and industrial sensor encapsulation.
Fluorosilicone Release Agents and Anti-Stick Coatings
With low surface tension and vinyl reactivity, vinyl fluorosilicone oil can be used to prepare fluorosilicone release papers, release films and anti-stick coatings, improving release stability and maintaining performance in oil- and solvent-resistant environments.
Oil-Resistant Defoamers and Lubrication Aids
Low-viscosity vinyl fluorosilicone oil can be used in oil-resistant defoamers, lubricating greases and fabric finishing agents, suitable for coatings, inks, textile printing and chemical processing.
Fluorosilicone Elastomer Formulation Adjustment
By adjusting vinyl content, viscosity and dosage, it can influence hardness, tensile strength, elongation, tear strength and media resistance of fluorosilicone rubber, making it useful for formulation development, lab trials and customer-specific customization.
Selection and Usage Recommendations
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Select by vinyl content: choose higher vinyl content for higher crosslink density and hardness; choose lower vinyl content for higher elongation or longer working time.
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Match viscosity to process: low viscosity suits liquid injection molding, potting and coating; medium-to-high viscosity suits formulations requiring better elasticity and mechanical properties.
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Control Si-Vi / Si-H ratio: calculate the ratio based on the active hydrogen content of the hydrogen-containing fluorosilicone oil to avoid incomplete curing or brittle parts.
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Avoid platinum catalyst poisons: amines, sulfur compounds, tin compounds and nitrogen-containing additives may inhibit platinum catalysis and should be kept out of the formulation.
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Store sealed and dry: avoid contact with acids, bases, moisture and oxidizers; use promptly after opening.
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Run small-scale trials first: curing speed, hardness, oil volume change and compression set vary by formulation, so lab verification is recommended before scale-up.
Vinyl Fluorosilicone Oil IOTA-25V
