FMV 4031 Vinyl terminated trifluoropropylmethylsiloxane Gelest Silicone (Si) >> Vinyl SEALANT ADHESIVE Vinyl terminated trifluoropropylmethylsiloxane. Offers better hydrocarbon compatibility (greater solubility), higher refractive index, greater solvent resistance (lower hydrocarbon solubility) and lower refractive index than analogous dimethylsiloxane homopolymers. Vinyl terminated trifluoropropylmethylsiloxane. Offers better hydrocarbon compatibility (greater solubility), higher refractive index, greater solvent resistance (lower hydrocarbon solubility) and lower refractive index than analogous dimethylsiloxane homopolymers.