FMS 131 Poly(3,3,3-trifluoropropylmethylsiloxane) 63148-56-1 Gelest Silicone Coatings Insoluble in water Poly(3,3,3-trifluoropropylmethylsiloxane). Used in coatings. Offers better hydrocarbon compatibility (greater solubility), higher refractive index, greater solvent resistance (lower hydrocarbon solubility) and lower refractive index than analogous dimethylsiloxane homopolymers. Poly(3,3,3-trifluoropropylmethylsiloxane). Used in coatings. Offers better hydrocarbon compatibility (greater solubility), higher refractive index, greater solvent resistance (lower hydrocarbon solubility) and lower refractive index than analogous dimethylsiloxane homopolymers.