Synthesis and properties of partially fluorinated amorphous ring containing polymers: Poly[bis(2,2-difluorovinyl)formal], poly[bis(2,2-difluorovinyl)difluoroformal], and poly[bis(1-deuterio-2,2-difluorovinyl)difluoroformal]

Three novel partially fluorinated monomers, bis(2,2-difluorovinyl)formal (I), bis(2,2-difluorovinyl)difluoroformal (II), and bis(1-deuterio-2,2-difluorovinyl)difluoroformal (III), were prepared. These monomers were polymerized in bulk via free radical mechanism. Monomer I produced a cross-linked polymer, but monomers II and III yielded amorphous polymers (II-P and III-P) having five- and six-membered rings along the backbone. Polymers II-P and III-P were soluble not only in fluorinated solvents but also in nonfluorinated solvents such as THF, 1, 4-dioxane, DMF, and DMSO. They have good thermal stability (onset of decomposition >400°C), high glass transition temperatures (105°C), and low dielectric constant (1.98-1.82 at frequency ranging from 0.1 to 3 × 10 ⁶ Hz). Furthermore, these polymers are completely amorphous and possess outstanding optical clarity extending from visible to near-IR regions. The refractive indices of both polymers were measured at various wavelengths to evaluate material dispersion. The material dispersions of II-P and III-P were similar and had low values, which are comparable to perfluorinated polymers and much lower than perdeuterioPMMA. The unique optical properties of these polymers make them attractive for use as optical materials.