| Abstract: | Ladder and partial ladder polymers have been obtained by self-condensation reactions of 1,2,4,5-tetraaminobenzene, 3,3′,4,4′-tetraaminodiphenyl ether, 3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenyl sulfone in polyphosphoric acid. The products thus obtained are highly colored compounds with good thermal stability. They seem to be made up of polyquinoxaline or dihydrophenazine or a mixture of these two recurring units. They are slightly soluble in methanesulfonic acid and concentrated sulfuric acid and have inherent viscosities in the 0.2 to 0.4 range. |
