Cross-linkable highly fluorinated poly(arylene ether ketones/sulfones) for optical waveguiding applications

Novel cross-linkable, highly fluorinated poly(arylene ether ketones/sulfones) have been prepared by copolycondensation reactions of perfluorinated aromatic ketone/sulfone with 4,4'-(hexafluoroiso-propylidene)diphenol and a tetrafluorostyrol-containing bisphenol (i.e., 1,1-bis(4-hydroxyphenyl)ethyl-1 -phenyl 2,3,5,6-tetrafluorostyrol ether). The reactions were conducted at low temperature in the presence of calcium hydride and cesium fluoride. The resulting polymers have Dumber-average molecular weights in the range of 25000-36000, excellent solubilities in common organic solvents, high glass transition temperatures (T-g) in the region of 150- 185 'C, and good thermal stabilities (T-d up to 480 degreesC). Tough, flexible, and transparent thin films of these polymers can be readily prepared by both solution casting and spin-coating. By adjusting the feed ratio of monomers, the refractive index and cross-linking density of the polymers can be readily controlled. Cross-linking of these polymers has been demonstrated by both thermal heating and UV irradiation. The cross-linked polymer thin films exhibit low optical loss (similar to0.5 dB/cm) and low birefringence (similar to2 x 10(-3)) at 1550 nm, demonstrating that they are promising candidates for optical waveguide materials.