New polymer syntheses. IX. Synthesis and properties of new conducting polyazomethine polymers containing main chain cycloalkanone and pyridine moieties

Abstract

Novel polyazomethines containing cycloalkanones or pyridine moieties were synthesized by the polycondensation of 2,5-bis(m-aminobenzylidene)cyclopentanone (BMAP, IV), 2,6-bis(m-aminobenzylidene)cyclohexanone (BMAH, V), 2,6-bis(p-aminobenzylidene)cyclohexanone (BPAH, VI), and 2,6-bis(m-aminostyryl)pyridine (BMAS, VIII) diamines with terephthalaldehyde in EtOH at 25°C. These polymers were yellow to orange in color, had reduced viscosities up to 1.42 dL/g, and had electric conductivities as high as 10 -11 -10 -12 S cm -1 . All the polyazomethines were insoluble in common organic solvents but dissolved completely in concentrated sulfuric acid. However, they were readily hydrolyzed in concentrated H 2 SO 4 . X-ray diffraction diagrams showed that the crystallinities of the polyazomethines were low. These azomethine polymers showed high thermal and thermooxidative stability and exhibited no appreciable decomposition up to 400°C in air. The electronic spectra of the polymers indicated a large bathochromic shift of the π-π * absorption band (∼360 nm) that was due to the presence of C=N bonds in the polymer main chain. Doping with iodine dramatically raised the conductivity and produced dark brown to black colored semiconductive polymers with a maximum conductivity on the order of 10 -7 S cm -1 . Furthermore, the morphology of selected examples of the four polyazomethines was examined by scanning electron microscopy.