Preparation and Properties of Silicon-Modified Polynaphthalimides

Abstract

Silicon-modified polynaphthalimides derived from 1,4,5,8-naphthalenetetracar-boxylic dianhydride, 4,4′-dinaphthalic anhydride and bis(1, 8-dicarboxynaphth-4-yl)dimethyl silane dianhydride and several types of aromatic diamines were prepared and their thermal stability was studied. The monomers of 4, 4′-dinaphthalic anhydride and bis(1, 8-dicarboxynaphth-4-yl)dimethyl silane dianhydride were also synthesized from acenaphthene followed by oxidation. Polyimides obtained were brittle because of the low molecular weight and the rigidity of the polymer structure. Therefore, no good thin films were made from the polyimides (the colour of which was dark brown). The imidization of polynaphthalimide occurred in the temperature range of 100–200 °C which is lower by about 50 °C than that of polypyromellitimide. The polyimides having a naphthalimide structure showed higher thermal decomposition temperature than the polyimides having a pyromellitimide structure derived from pyromellitic dianhydride. However, the decomposition temperature of silicon-modified polynaphthalimides decreased with increasing silicon content in the polyimides.