Poly‐1.3.4‐oxadiazoles. IV. Poly‐1.3.4‐oxadiazoles containing pyridine rings

In order to obtain tractable aromatic poly(1.3.4‐oxadiazoles), the polycondensation of pyridinedicarboxylic dihydrazides has been investigated according to the solution polycondensation procedure using fuming sulfuric acid or polyphosphoric acid as solvent and condensing agent. The resulting polymers were not wholly composed of the 1.3.4‐oxadiazole structure, and their molecular weights were rather low (ηsp/c up to 0.18 dl/g). Some properties of the polymers, such as IR‐ and UV‐spectra, solubility, and thermal stability, were compared with those of authentic poly(pyridine‐1.3.4‐oxadiazoles).