| Abstract: | Two fluorinated aromatic bis(o‐aminophenol)s, 1,1‐bis(3′‐amino‐4′‐hydroxyphenyl)‐1‐(3′‐trifluoromethylphenyl)‐2,2,2‐trifluoroethane (6FAP) and 1,1‐bis(3′‐amino‐4′‐hydroxyphenyl)‐1‐(3′,5′‐ditrifluoromethylphenyl)‐2,2,2‐trifluoroethane (9FAP) were synthesized, which were allowed to polycondense with aromatic diacyl chlorides to afford the fluorinated aromatic polybenzoxazoles (PBOs) via a conventional two‐step procedure in which the low‐temperature solution polycondensation process was first performed to yield poly(o‐hydroxyamide)s (PHAs) followed by the thermal cyclodehydration to give the PBOs. Experimental results indicated that the PHAs had inherent viscosities in the range of 0.29–0.68 dL/g, showing excellent solubility in organic solvents. The PHAs could be thermally cyclodehydrated into the corresponding PBOs at 260–370 °C. The obtained PBOs exhibited enhanced glass‐transition temperature but decreased solubility with respect to the PHAs. The PBOs showed glass‐transition temperatures in the range of 315–337 °C and excellent thermal stabilities with 5% original weight‐loss temperatures (T5) of >513 °C. Additionally, the PBO films had average refractive index of 1.5298–1.5656, birefringence of 0.0051–0.0092, and low dielectric constants of 2.57–2.70. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 |
