Cross-linkable Highly Fluorinated Polymers with Tunable Refractive Index
- PDF / 292,059 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 2 Downloads / 252 Views
0888-V09-21.1
Cross-linkable Highly Fluorinated Polymers with Tunable Refractive Index Yinghua Qi,1 Jia Jiang,2 Claire L. Callender,2 Jianfu Ding,1 and Michael Day1 Institute for Chemical Process and Environmental Technology, National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada 2 Communications Research Centre Canada, Ottawa, Ontario K2H 8S2, Canada 1
ABSTRACT Novel cross-linkable, highly fluorinated poly(arylene ether ketone/sulfone)s have been prepared by copolycondensation reactions of a perfluorinated aromatic ketone or sulfone with 4,4'-(hexafluoroisopropylidene)diphenol (6F-BPA)/4,4’-isopropylidene bis(2,6-dibromophenol) (4Br-BPA) and a tetrafluorostyrol-containing bisphenol, at low temperature in the presence of calcium hydride and cesium fluoride. Property investigations have shown that these polymers can be easily processed into thin films, have good thermal stability, and exhibit low optical loss at 1550 nm (0.4 – 0.5 dB/cm). The refractive index can be tailored over a range of 1.50 to 1.57, allowing the polymers to be used as both core and cladding materials in optical waveguiding applications. INTRODUCTION Organic polymers are increasingly attractive alternatives to inorganic materials for optical waveguide devices in metro and local area networks using coarse wavelength division multiplexing (CWDM) owing to their low-cost fabrication and relatively good properties[1-3]. Optical waveguide devices are often comprise a multilayer channel waveguide structure, where a guided mode is propagated in ridge formed in a core material with a higher refractive index than the surrounding cladding layers. For each waveguide structure, a tightly specified difference in refractive index between core and cladding is required to achieve optimized device performance. As a result the development of optical materials that have adjustable refractive index is extremely valuable. In addition, to facilitate multilayer device fabrication, and to optimize device robustness, polymers with the ability to be cross-linked either thermally or photochemically are also highly desired. Among the optical polymers developed over the last decade, highly fluorinated poly(arylene ether ketones/sulfones) (FPEKs/FPESs) appeared to be one of classes of promising candidates due to the low intrinsic absorption at telecommunication wavelengths, good thermal, mechanical and chemical stability, low dielectric constant and high glass transition temperature (Tg)[4,5]. In addition, due to the existence of flexible ether linkages in polymer backbone, these polymers commonly have a lower birefringence compared with other high Tg polymers[6]. To apply this class of materials in practical device fabrication, we have recently designed and prepared a novel fluorinated bisphenol containing a thermally and photochemically crosslinkable group. By introducing the bisphenol and a heteroatom such as bromine into FPEK/FPES structures, a series of cross-linkable highly fluorinated copolymers with controllable crosslinking functionality and fine-tunable
Data Loading...
