Property tailored perfluorocyclobutyl (PFCB) copolymers for optical devices

Organic polymers are increasingly attractive alternatives to inorganic materials in telecommunication devices. Polymers offer flexibility, low cost fabrication and connection, high transparency in the visible and near-infrared spectra, and versatility in structure, properties, and grades for task specific integration such as local-area-network applications. Halogenated polymers in particular show negligible transmission losses in the range desired and fluoropolymers represent the lowest loss examples of organic polymers to date. However, commercial perfluoropolymers in general are limited by poor processability, non-trivial refractive index matching, and they typically do not exhibit the thermal and thermomechanical stability required for some commercial processes and extreme environment in-use applications. Our strategy has focused on the thermal cyclopolymerization of trifunctional and bifunctional aryl trifluorovinyl ether monomers to perfluorocyclobutane (PFCB) copolymers. PFCB polymers and copolymers enjoy a unique combination of properties well suited for optical applications such as high temperature stability, precisely controlled refractive index, low moisture absorption, excellent melt and solution processability, a high thermooptic coefficient, and low transmission loss at 1300 and 1550 nm. Copolymerization reactions offer tailored thermal and optical properties by simple choice of comonomer. PFCB polymers can be solution or melt microfabricated via standard methods and can also be processed by soft-lithography techniques. Polymerization and processing parameters and characterization including thermal properties (Tg = 120-350 degree(s)C), optical loss (< 0.2 db/cm at 1550 nm), refractive index tunability (1.449-1.508 at 1550 nm), low birefringence, and optical stability is presented.