Fluorinated Poly(arylene ether sulfide) for Polymeric Optical Waveguide Devices

Fluorinated poly(arylene ether sulfide)s containing an ethynyl group (E-FPAESI) were synthesized by nucleophilic aromatic substitution from 4,4‘-(hexafluoroisopropylidene)diphenol (6FBPA) and an excess of pentafluorophenyl sulfide, followed by reaction with 3-ethynylphenol. The molecular weights (M_n's) and polydispersities (M_w/M_n's) of the E-FPAESI determined by GPC with polystyrene standard were in the range 14 200−25 200 and 2.23−2.47, respectively. The polymer films were fabricated by spin-coating and cross-linked by thermal curing. The cured films had good chemical resistance for common solvents such as acetone, tetrahydrofuran (THF), methylene chloride, chloroform, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). The glass transition temperature of E-FPAESI was changed from 120 to 160 °C after curing and showed high thermal stability up to 489 °C. At 1.55 μm wavelength, the refractive indices and birefringences of the films were in the range 1.5200−1.5515 and 0.0034−0.0044, respectively, depending on feed ratio of 6FBPA and 4,4‘-(trifluoromethylphenylisopropylidene)diphenol (3FBPA). The optical loss for E-FPAESI was measured to be less than 0.40 dB/cm.