SYNTHESIS AND CHARACTERIZATION OF POLY(OXY-1,3-PHENYLENECARBONYL-1,4-PHENYLENE) AND RELATED POLYMERS

The title composition, isoPEK, was prepared from 4-fluoro-3'-hydroxybe nzophenone in N-methylcaprolactam at 225 degrees C. Cyclomer formation interfered with polymerization at lower temperatures in alternative s olvents and dominated in dilute solutions. The 50/50 to 70/30 copolyme rs of PEK and isoPEK were prepared using 4-fluoro-4'-hydroxybenzopheno ne. An analogous composition, poly(oxy-1,3-phenylenecarbonyl-1,4- phen yleneoxy-1,4-phenylenecarbonyl-1,4-phenylene) or isoPEKEK, was prepare d from 4,4'-difluorobenzophenone and 3,4'-dihydroxybenzophenone using similar conditions. Thermal crystallization of the copolymers was succ essful, but isoPEK and isoPEKEK were only capable of solvent-induced c rystallization. The semicrystalline materials were studied by thermal analysis and X-ray diffraction. The copolymers melted at 264-307 degre es C and possessed random microstructures with isomorphic crystallizat ion of the PEK and isoPEK repeat units. IsoPEK and isoPEKEK melted, re spectively, at the low temperatures of 180 and 193 degrees C. IsoPEK c rystallized with both Form 1 and Form 2 unit cells, while isoPEKEK and the copolymers crystallized with the Form 1 unit cell. IsoPEK was als o prepared by ring-opening polymerization of its cyclomers in the melt using cesium fluoride as catalyst. The 3,4' catenation of the isoPEK repeat unit and the related monomers was used to rationalize the uniqu e chemistry and properties of these polymers.