Synthesis and properties of some aromatic polymers

Abstract Multinuclear aromatic compounds are distinguished by considerable thermostability. In a number of cases they have been shown to be endowed with semiconductor properties. In view of this the development of a method of synthesis and investigation of aromatic polymers with a common system of conjugated bonds has both theoretical and practical interest. Such substances have been synthesized by the authors on decomposing bisdiazo compounds by an ammoniacal solution of univalent copper, and also on decomposition of bisnitroso acetates. In particular, 4,4′‐bisdiazobiphenyl, 4,4′‐bisdiazobitoyl, 4,4′‐bisdiazobiphenyl‐3,3‐dicarboxylic acid, and benzidine N,N′‐bis‐nitroso acetate were employed. On decomposition of the bisdiazo compounds a powder of orange to brown color was formed, soluble in concentrated sulfuric acid and isoluble in most organic solvents. Analysis showed it probably to possess the composition: where R may be H, COOH, or CH3. On the average one azo group is present for each 4–10 benzene rings and two chlorine atoms for each 10–20 rings. The mean molecular weight determined for one of the carboxylated polymer specimens was found to be 3000. On heating to 400° the polymer decarboxylates. At 450° decomposition sets in. Viscosity curves of the solutions (plots of ηsp/C vs. C) exhibit an anomalous rise within the limits C = 0.1–1%. The concentration of unpaired electrons in the polymers was shown by the electron resonance method to be ∼1019/g. Heating the substances leads to an increase in concentration of unpaired electrons by 1–2 magnitudes. The spectra and x‐ray diagrams of the substance were obtained. Evidently the formation of polymers from bisdiazo compounds is of a radical nature, leading to the formation of stable radicals of low activity. Low molecular fractions isolated from the polymers are fusible and soluble in benzene. They are capable of reacting with diethynylbenzene with the formation of nonmelting and insoluble thermostable products. Carboxylated polymers form salts with transition elements that evidently are of the nature of intracomplex compounds with intermolecular crosslinkage. Products of the decomposition of benzidine bisnitroso acetate are in general similar to those resulting from bisdiazodiphenyl, but contain less unpaired electrons.