Preparation and characterization of polyhedral oligomeric octanitrophenylsilsesquioxane

Nitrification of polyhedral oligomeric octaphenylsilsesquioxane (OPS) by fuming nitric acid was studied to synthesize the octanitrophenylsilsesquioxane (NPS). Effects of the concentration and the nitrification time of nitric acid on numbers of nitryl groups in NPS molecule were investigated by controlling the nitrification temperature at 12°C~15°C. The chemical structure and molecule weight of NPS were characterized by elementary analysis, FT-IR, ¹H-NMR and GPC. Controlling the nitrification time at 20 h, it was found that the lower nitric acid concentration, the weaker nitrification ability to OPS. NPS of one nitryl group on every phenyl could be prepared when the initial nitric acid concentration was 90.06% and the nitrification time was up to 20 h. With the initial nitric acid concentration of 90.06%, number of the nitryl groups of every NPS molecule increased with the nitrification time increasing, but maximum number of the nitryl groups was not more than 8.