MOLECULAR-STRUCTURE OF SOME MODEL COMPOUNDS FOR POLY(ARYL ETHER KETONE)S

The molecular structure of a series of model compounds for poly(aryl e ther ketone)s was investigated by means of C-13 NMR spectroscopy, quan tum chemical calculation, and wide-angle X-ray scattering. The compari son of the chemical shifts for the model compounds dissolved in 98% H2 SO4 and CDCl3 (or CDCl3 + DMSO-d(6)) suggested that their carbonyl gro ups are partially protonated by sulfuric acid and the induced positive charges are delocalized in their aromatic rings. This result was supp orted by the charge distribution obtained by quantum chemical calculat ions. The model compounds were also used to characterize the molecular structure of poly(aryl ether ketone)s. The length of the repeating un it of the polymer chain, which was calculated based on the whole chain length or fragment chain length of the model compounds obtained by :s emiempirical PM3 method, is compared with the c-axis of the crystal un it cell of the polymer For poly(aryl ether ketone)s containing bipheny l moieties, the length of the c-axis of the unit cell is approximately twice that of the repeating unit of the macromolecule.