A series of hydroxy-containing polyimides, containing pendent hydroxyl groups ortho to the heterocyclic imide nitrogen, were prepared via the solution condensation of aromatic dianhydrides with bisaminophenols. The polyimides were found to undergo thermal conversion to polybenzoxazoles upon heating between 350 and 500 °C under nitrogen or vacuum. The thermal conversion was accompanied by loss of carbon dioxide. No other volatile byproducts were detected by IR or NMR. Structures were confirmed by IR, solid-state NMR, and elemental analysis. Polybenzoxazole films, obtained by the thermolysis of solvent-cast poly(amic acid) or polyimide solutions, displayed excellent solvent resistance and good thermal stability. Insolubility of the polybenzoxazoles in all solvents tested indicates possible cross-linking. No crystallinity was observed by X-ray diffraction. Due to the insolubility of the resulting polybenzoxazoles, model compound reactions were also investigated. In the vapor phase at 400 °C, N-(2-hydroxyphenyl)phthalimide underwent intramolecular thermal conversion to 2-phenylbenzoxazole in 83% yield, emulating the polyimide reactions. Thermal conversion of N-(2-hydroxyphenyl)phthalimide in the melt at 400 °C resulted in the formation of intermolecular reaction products. The intermolecular reactions may be a source of possible cross-links, which would explain the insolubility of the polybenzoxazoles.

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The compounds 2,phenyl]propane and 2,2-bis[4-(4-fluorobenzoyl)phenyljhexafluoropropane were synthesized, and each was polymerized with Bisphenol A or Bisphenol AF (155 °C for 3-6 h in , -dimethylacetamide (DMAc)) to give an homologous series of four, thermally stable, aromatic poly(ether ketones) in yields greater than 90%. Incorporation of hexafluoroisopropylidene (6F) and/or isopropylidene (6H) groups in the poly(ether ketone) backbone greatly enhanced the solubility of these polymers (compared to Victrex PEEK) in common organic solvents. Thermal stabilities by TGA for the polymer series ranged from 485 to 553 °C in air at the point of 10% weight loss. Glass transition temperatures (Tg) ranged from 169 to 180 °C by DSC. The synthesis and characterization of poly(ether ketones) containing 6F and 6H groups in the backbone are reported along with a study of the effect that replacing the 6H group with the 6F group has on the properties of the polymers.

SYNOPSISA series of fluorinated aromatic polyethers was synthesized via aromatic nucleophilic substitution of highly fluorinated aromatics ( 1,2,4,5-tetrafluorobenzene, hexafluorobenzene, and decafluorobiphenyl) with bisphenol AF or bisphenol A. Polymerization with 1,2,4,5tetrafluorobenzene was not observed, and polymerization of hexafluorobenzene with bisphenol proceeded only if the potassium carbonate-bisphenol ratio was carefully controlled.The polymer condensed from decafluorobiphenyl and bisphenol AF was prepared in 77% yield with an inherent viscosity of 1.01 dL/g. The polymer prepared from the condensation of decafluorobiphenyl with bisphenol A was obtained in 48% yield with an inherent viscosity of 0.28 dL/g. These polymers were very soluble in common organic solvents, formed clear, colorless films, and were thermally stable (> 450°C by TGA). The fully fluorinated polymer exhibited low water uptake (0.3% ) and dielectric constant (2.17). 0