New copolymers of perfluoro-2-ethyl-2-methyl-1,3-dioxole and perfluorovinyl ether with low non-monotonic refractive index

Abstract

Copolymers of perfluoro-2-ethyl-2-methyl-1,3-dioxole and perfluoro-5-methyl-3,6-dioxanon-1-ene were synthesized using high-pressure technique without initiators. Copolymers have molecular weight of (1.2–4) • 10⁴ and possess high optical transparency in the telecommunication C-band region of 1530–1565 nm. Refractive index n of copolymers as a function of ether mol.% in the macromolecule x was investigated. It is established that the curve n(x) is non-monotonic, the difference of refractive indices of copolymers with various x differs by Δn = 0.015. The synthesized materials are amorphous, capable of film formation, and can be used for the fabrication of optical fibers and integrated optical waveguides with numerical aperture NA from 0.13 to 0.2, with waveguiding core and cladding made of perfluorinated materials.