Preparation And Properties Of New Low-loss And Low-birefringent Photosensitive Poly(Aryl Ether)s For Optical Waveguide

The purpose of this paper is to obtain excellent polymer optical waveguidematerials with combination property, such as high thermal stability, precisecontrollability of refractive index, low birefringence and low optical loss during thetelecommunication wavelengths. With designing the molecular structures, a series ofnovel photosensitive poly(arylene ether)s with good combination property have beendesigned and synthesized.1．New chalone contain trifluoromethyl group is designed and synthesized, called4,4’-fluoro-3,3’-(trifluoromethyl) chalcone(4,4’-3,3’FC). It is synthesized withultrasonic radiation and dry HCl (g) as catalyst. A series of novel highly fluorinatedphoto-cross-linkable poly(arylene ether)s (HFPAE-xy)bearing chalcone group in themain chain have been designed and synthesized for photonic applications bycopolycondensation reactions of4,4’-3,3’FC with potassium salt of4,4’-(hexafluoro-isopropylidene)diphenol(6F-BPA) and decafluorobiphenyl (DFBP).The chemical structure of resulted monomer and polymers have been confirmed byFT-IR、1H NMR、19F NMR and UV/Vis spectra.2．HFPAE-xy have good photosensitiveness, solubility, thermal stability, mechanicalproperty and so on. The biggest absorption peak of polymer was at315nm, thephoto-reaction rate of>C=C<in chalcone group was fast and the maximum degreeof>C=C<photo-cyclization was up to about77%after15min without photoinitiatorat room temperature. Cross-linking reaction of polymers were characterized byFT-IR、XPS too. HFPAE-xy can soluble in DMAc、DMF、CHCl3、THF and so on,but they can’t soluble in any organic solvent after crosslinking. The glass transitiontemperature (Tg) of HFPAE-xy were161-175°C， the first decompositiontemperature of polymer before was above345oC,and after crosslinking, W1%wasabove360oC and no Tg. Mechanical property of HFPAE-xy were increased aftercrosslinking, for instant, tensile strength were increased from63-72MPa to69-80MPa. From the characterization of XRD, all HFPAE-xy hadn’t crystallization.3．The refractive index and birefringence of polymers can be precisely controlled notonly by the copolymerzation ratio of monomers, but also by the UV irradiation time.The refractive index of polymer films decreased with the increase of the fluoridecontent and UV irradiation time, and birefringence of polymer films decreased withthe increase of the mononer content and UV irradiation time. After UV irradiation 30min, the birefringence of HFPAE-10was declined from0.0044to0, wesuccessfully prepared zero-birefringence of polymer optical waveguide materials.The HFPAE-xy presents higher thermo-optical coefficient, the most thermo-opticalcoefficient were-8.5E-5and-6.8E-5, after UV, they all became bigger, at the mostof-1.1E-4. HFPAE-xy hadn’t almost light absorption at the telecommunicationwavelengths of1.3and1.55μm from near infrared spectrum.