SEQUENCE DISTRIBUTION OF POLY(ETHER-SULFONE) POLY(ETHER-KETONE) COPOLYMERS BY MASS-SPECTROMETRY AND C-13 NMR

The sequence distributions of four poly(ether-sulfone)/poly(ether-keto ne) (PES/PEK) copolymer samples were determined by means of fast atom bombardment mass spectrometry (FAR-MS) and by C-13 NMR spectroscopy. T he controlled partial degradation of the copolymer chains to produce o ligomers suitable of FAB-MS analysis was performed with sodium methoxi de in dimethyl sulfoxide solution at 130 degrees C, and the experiment al conditions were optimized. The sequential arrangements of ether-sul fone/ether-ketone units present in these materials were estimated by a best-fit minimization method using the MACO4 computer program which c ompares the experimental FAB-MS spectral intensities with theoretical intensities. Random PES/PEK copolymer samples showed quite the same se quence arrangements as expected from monomer feed-ratios used in the s yntheses. Instead, a PES/PEK copolymer sample expected to be exactly a lternating (from the synthesis procedure) showed 44% of random sequenc es owing to the transetherification reaction which occurred in the syn thesis. The results of sequential analysis obtained from C-13 NMR data compare well with the data obtained by the FAB-MS analysis.