EDV 2025 Vinyl terminated diethylsiloxane-dimethylsiloxane copolymer Gelest Silicone (Si) >> Vinyl SEALANT Vinyl terminated diethylsiloxane-dimethylsiloxane copolymer. Used in RTV silicone formulations. Offers better hydrocarbon compatibility (greater solubility) and higher refractive index than analogous dimethylsiloxane homopolymers. Vinyl terminated diethylsiloxane-dimethylsiloxane copolymer. Used in RTV silicone formulations. Offers better hydrocarbon compatibility (greater solubility) and higher refractive index than analogous dimethylsiloxane homopolymers.