STUDIES ON REGULARITY OF POLY PHENYLSILSESQUIOXANE CHAINS

IR and ~(29)Si NMR were used to determine the structures of ladderlike polymer polyphenylsilsesquioxanes (PPS). It was found that PPS with lots of defects had a wide and strong absorption band in 1000—1400 cm~(-1) with only one sharp peak at 1137 cm~(-1) while two peaks (1130 and 1045 cm~(-1) were observed for PPS with perfect ladderlike structure. Branching and crosslinking of PPS lead to the reduction of 1045 cm~(-1) peak. ~(29)Si NMR spectra, however, showed two peaks (δ=-78 ppm and -87 ppm when δ_(HMDS)=0 ppm) for defective or branched PPS. The -87 ppm peak is related to the ladderlikely constructed Si atoms and -78 ppm corresponds to defective Si atoms. PPS with defects less than 0.1% chain units was obtained by azeotropic polycondensations.

STUDIES ON REGULARITY OF POLY PHENYLSILSESQUIOXANE CHAINS

 IR and ²⁹Si NMR were used to determine the structures of ladderlike polymer polyphenylsilsesquioxanes (PPS). It was found that PPS with lots of defects had a wide and strong absorption band in 1000—1400 cm^-1 with only one sharp peak at 1137 cm^-1 while two peaks (1130 and 1045 cm^-1 were observed for PPS with perfect ladderlike structure. Branching and crosslinking of PPS lead to the reduction of 1045 cm^-1 peak. ²⁹Si NMR spectra, however, showed two peaks (δ=-78 ppm and -87 ppm when δ_HMDS=0ppm)for defective or branched PPS.The -87 ppm peak is related to the ladderlikely constructed Si atoms and -78 ppm corresponds to defective Si atoms.PPS with defects less than 0.1% chain units was obtained by azeotropic polycondensations.