Fluorosilicone rubber, also known as γ-trifluoropropyl methyl polysiloxane, is a side-chain modified silicone elastomer. Generally, 0.2% to 0.4% of vinyl siloxane is introduced into the molecular chain for copolymerization modification. It is a colorless, transparent, high-viscosity, plastic, straight-chain polymer compound with a main chain composed of silicon and oxygen atoms. The side groups attached to silicon include methyl, vinyl, and trifluoropropyl groups, with a molecular weight ranging from 500,000 to 800,000.
 
Main features 
Compared with methyl vinyl silicone rubber, fluorosilicone rubber exhibits superior performance in terms of oil resistance, solvent resistance, and chemical resistance. Even compared with fluororubber, its oil and solvent resistance are not inferior. After immersion in the same medium, temperature, and time, fluorosilicone rubber exhibits excellent durability and can be said to be the only elastomer that is resistant to non-polar media at -68℃～232℃. In addition, it also has good performance in resisting gasoline containing methanol. Even in the gasoline/methanol mixed system, the hardness, tensile strength, and volume change of the vulcanized rubber are very small. After a long-term immersion test of 500 hours, there is almost no change in various physical properties.
 
The high-temperature decomposition process of fluorosilicone rubber is similar to that of silicone rubber, mainly including side chain oxidation, main chain breakage, side chain thermal decomposition, and various composite reactions. Because the decomposition products can also cause main chain breakage, its heat resistance is usually slightly lower than that of silicone rubber. At a temperature of 200°C, fluorosilicone rubber has begun to oxidize and age, but by adding a small amount of heat stabilizers such as iron, titanium, and rare earth oxides, its heat resistance can be significantly improved, and it can maintain sufficient heat resistance even at high temperatures of 250°C. The influence of temperature on fluorosilicone rubber is greater than that of silicone rubber, but less than that of fluororubber. Foreign studies have also investigated the service life of fluorosilicone rubber under conditions of 150°C×2000 hours, 175°C×5000 hours, and 200°C×4000 hours, and the results show that it is second only to methyl vinyl silicone rubber.
 
Like ordinary silicone rubber, fluorosilicone rubber has good low-temperature performance. Because it is a linear polymer with a soft Si-O backbone, its low-temperature characteristics are better than those of fluororubber with a C-C backbone. Among them, fluorosilicone rubber (LS-2370U) has better low-temperature characteristics, with a brittle temperature as low as -89℃, while general fluororubber is about -30℃.
The electrical properties of fluorosilicone rubber are similar to those of ordinary silicone rubber, and there is little change under harsh conditions such as high temperature, low temperature, humidity, oil, solvents, chemicals, ozone, etc. Although its radiation resistance is not outstanding, its radiation aging resistance is better than that of methyl vinyl silicone rubber. Its weather resistance is excellent, and even after 5 years of exposure, it can still maintain good performance. In the ozone environment, fluorosilicone rubber has not been found to have cracks or cracks after dynamic or static tests. In addition, its mildew resistance, physiological inertness, and anticoagulant properties are also very good.
Fluorosilicone rubber combines the advantages of fluororubber and silicone rubber, with excellent resistance to polar and non-polar solvents and oil resistance, and can be used for long-term use in the range of -55 to +200℃. It is commonly used in the production of oil-resistant tubing, belts, sealing strips, seals, oil seals, and pipes for transporting acid and alkali media. It has wide applications in the automotive industry, aerospace industry, petrochemical industry, electronic communication, precision instruments, medical and health care, and other fields.
 
Main applications
Aviation field: diaphragms for valves in the fuel tank pressure regulating pipeline, diaphragms for fuel tank vent valves (cloth-clad films with fluorosilicone rubber coating and polyester cloth as the skeleton material that can be used in kerosene vapor at -55℃～200℃ and RP kerosene at 150℃); static and dynamic seals, etc.
Automotive products: fuel level indicator sensor hose, atomizer oil pump diaphragm, fuel pump diaphragm, corrugated sheath, engine crankshaft rear seal ring, cylinder gasket, fuel pump seal, fuel tank cover gasket, fuel tank refueling gasket, oil filter seal, etc.
Other aspects: sealing parts resistant to fluorine-chlorine oil, fluorine-bromine oil, trichlorobiphenyl, H2S solution, liquid nitrogen, etc.

Summary
In practical applications, the performance of fluorosilicone rubber is affected by various factors, such as production process, formulation design, and usage environment. Therefore, when selecting and using fluorosilicone rubber, it is necessary to consider its performance characteristics and relevant technical requirements based on specific needs and application scenarios.