1,7-DICARBA-CLOSO-DODECABORANE(12) POLYMERS .1. META-CARBORANYLENE BRIDGED AROMATIC POLYAZOMETHINES

New meta-carboranylene-bridged aromatic polyazomethines having inherent viscosities ranging from 0.2 to 0.5 dl · g-1 ( M ̄n = 5000-30,000) were synthesized by solution polycondensation of 1,7-dicarbadodecaborane(12)-1,7-dicarboxaldehyde with aromatic diamines. In order to obtain comparative kinetic and spectroscopic data, model compounds were also prepared by the condensation of benzeneamine with carborane dialdehyde and 1,3-benzenedicarboxaldehyde. Almost all the polyazomethines were amorphous and soluble in a variety of organic solvents including chloroform, meta-cresol, dioxane, dimethylacetamide. Transparent and flexible films could be cast from chloroform solutions. When studied by dynamic thermogravimetric analysis in air and in argon, these polymers did not lose weight below 600°C and the residue left on heating at 1000°C was 92% of the initial sample weight. However, isothermal ageing in air at 400, 500 and 600°C for 500 hr suggested that the organic part of the macromolecules was severely degraded by oxidation. During this thermal treatment, the carborane clusters were oxidized into boric anhydride and boric acid. © 1990.