Hydrolytically stable phosphorus-containing monomers, such as 4,4'-bis(fluoro-pheny1)methylphosphine oxide (BFPMPO), 4,4'-bis(hydroxyphe1nyl)methylphosphine oxide (BOHPMPO), and 4,4-bis(hydroxyphenyl)phenylpliosphine oxide (BOHPPO), were synthesized and used in nucleophilic aromatic Substitution polycondensation to prepare poly(ary1ene ether phosphine oxide) engineering thermoplastics. The synthesis and characterization of these novel polymers are described. It was determined that by incorporating the phosphine oxide moiety into the polymer backbone, certain properties of the resulting poly(ary1ene ether) were substantially improved, such as an increase in Tg, thermal stability in air, modulus, and char yield compared with control poly(ary1ene ether su1fone)s. The :high char yields obtained for these polymers in air along with observed intumescence indicates that these materials have improved fire resistance. Preliminary cone calorimetry measurements support this conclusion.

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Studies on the synthesis of high molecular weight polybenzoxazoles (PBOs) in polyphosphoric acid (PPA) and investigations of their hydrolytic stability in aqueous methanesulfonic acid are described. The polymerization of PBOs based upon 2,2 1 -bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP) and 4,4 1 -oxydibenzoic acid (ODBA) was investigated as a function of the percentage of P 2 O 5 content in PPA, polymerization temperature, percentage monomer (total weight of monomers/weight of monomers plus PPA), and reaction time. It was found that the percentage of P 2 O 5 content was the most important polymerization variable and that PPA with more than 85% P 2 O 5 content was required to achieve high molecular weight PBOs. Hydrolytic stability of PBOs prepared from selecting 6FAP and either ODBA, isophthalic acid (IA), or terephthalic acid (TA) was investigated by solution viscosity measurements, 1 H-NMR and FTIR spectroscopy. The hydrolysis experiments were conducted in aqueous methanesulfonic acid solutions at room temperature, 50, and 80 2 C. The 6FAP/ODBA PBO showed improved stability over time with respect to the 6FAP-IA and 6FAP-TA PBOs, which may be due to the decreased electrophilicity of the carbon atom of the oxazole ring. But, the inherent viscosities of all the PBOs decreased over time and 1 H-NMR and FTIR spectroscopic evidence for chain scission was obtained. Benzoxazole model compounds, 2,2 1 -Bis(2-phenylbenzoxazol-6-yl)hexafluoropropane, 2,2 1 -bis[2-(4-phenoxyphenyl)benzoxazol-6-yl]hexafluoropropane, were synthesized from selecting 6FAP and ether 4-phenoxybenzoic acid or benzoic acid in N-cyclohexylpyrrolidinone. Nuclear magnetic resonance spectroscopic data provided direct evidence of hydrolysis of oxazole functional groups.

The physical aging properties of amorphous thermoplastics having various terminal groups were investigated with creep recovery and linear dilatometry. The structure of the chain end groups affected physical aging at lower molecular weights; however, above the critical molecular weight for entanglements the end‐group effect on aging diminished. Experimental densities and glass‐transition temperatures were also end‐group dependent. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2850–2860, 2003