Synthesis and Characterization of Fluorinated PBO With High Thermal Stability and Low Dielectric Constant

A series of novel fluorinated benzoxazole polymers (6FPBO) with high thermal stability and low dielectric constant were synthesized by copolymerization of 1,3-diamino-4, 6-dihydroxybenzene dihydrochloride (DAR), purified terephthalic acid (PTA) and various amount of 4'4-(hexafluoroisopropylidene) bis(benzoic acid) (BIS-B-AF) in the medium of polyphosphoric acid (PPA). 6FPBO fibers were then obtained via dry-jetwet-spinning technique and characterized by Fourier transform infrared (FTIR) spectra, thermogravimetric analysis (TGA), broadband dielectric spectrometer, single fiber tensile testing machine, and scanning electron microscopy (SEM). The FTIR spectrum of 6FPBO fibers indicated that the fluorine groups were incorporated into PBO molecular chains successfully. TGA curves revealed that 6FPBO fibers possessed high thermal stability, just as pure PBO fibers. Moreover, the dielectric constant spectra of 6FPBO showed that the polymers had low dielectric constant, especially in the range of high-frequency.