Synthesis of Highly Fluorinated Poly(arylene ether sulfide) for Polymeric Optical Waveguides

Ethynyl-terminated fluorinated poly(arylene ether sulfide) (E-FPAESI) was synthesized via nucleophilic aromatic substitution from dihydroxy monomer and pentafluorophenyl sulfide, followed by the reaction with 3-ethynylphenol. Dihydroxy monomer was synthesized in four steps via bromination, Grignard, Suzuki cross-coupling, and demethylation techniques. The number-average molecular weights and polydispersities of the E-FPAESI were in the ranges of 7700−23 000 and 1.53−2.89, respectively. The glass transition temperatures of the polymers varied from 126 to 171 °C and upon curing in the range of 168−236 °C. E-FPAESI exhibited high thermal stability up to 451−483 °C. The refractive indices and birefringences of the spin-coated polymer films were in the ranges of 1.4943−1.5047 and 0.0004−0.0009 at 1550 nm wavelength, respectively. The optical loss for E-FPAESI was about 0.45 dB/cm at 1550 nm wavelength.