| Abstract: | Polyimides that contained thianthrene and dibenzo-p-dioxins units were synthesized. The tricyclic fused rings were successfully incorporated by polymerizing the diamines of the units with aromatic tetracarboxylic dianhydrides. The resulting polyamic acids were converted to polyimides by thermal cyclodehydration. The influence of the tricyclic units on the properties of the polyimides has been investigated. Polyimides that contained dibenzo-p-dioxins (ODP) exhibited sufficient thermal stability but were insoluble even in concentrated sulfuric acid. The introduction of a methyl group did not produce an appreciable increase in solubility. Thianthrene polyimides were considerably less stable than the equivalent polymers derived from open-chain diamine, 4,4′-diaminodiphenyl sulfide but were partly soluble in acid solvents. The results are discussed in terms of packing the polymer molecules. |
