Polybenzodipyrroloquinoxalines

Three polymers have been prepared by the condensation of benzo1,2-b;5,4-b ′]-dipyrrolo-2,3,4,5-tetraone (I) with 1,2,4,5-tetraaminobenzene (II), 3,3 ′-diaminobenzidine (III), and 3,3 ′,4,4 ′-tetraaminodiphenyl ether (IV) in polyphosphoric acid (PPA) solution. The polymer structures were substantiated by comparison of their infrared and ultraviolet spectra with spectra of the model compounds and elemental analysis. The polymers had inherent viscosities of 0.86-0.90 (H₂SO₄) and thermal stabilities of 460°C and up to 700°C in air and nitrogen atmospheres, respectively.