Synthesis and characterization of 1,3,4‐oxadiazole‐containing polyazomethines

Abstract

AbstractNovel 1,3,4‐oxadiazole‐containing polyazomethines were synthesized by the polycondensation of diamines, 2,5‐bis (m‐aminophenyl)‐1,3,4‐oxadiazole (BMAO) and 2,5‐bis (p‐aminophenyl)‐1,3,4‐oxadiazole (BPAO), with aromatic dialdehydes, isophthalaldehyde and terephthalaldehyde, in m‐cresol at 20°C. These polymers were yellow to orange in color and had reduced viscosities up to 1.13 dL/g and electric conductivity as high as 10−11−10−12 S cm−1. All the polyazomethines were insoluble in common organic solvents but dissolved in concentrated sulfuric acid. Thermogravimetry showed that thermal degradation started at around 400°C in air and nitrogen atmospheres. Doping with iodine markedly increased the conductivity and produced the black‐colored semiconductive polyazomethines with a maximum conductivity of the order of 10−6 S cm−1. Electronic spectra of the undoped polymers indicated a large bathochromic shift of the absorption maxima due to CN bonds of the monomer diamines (285 nm for BMAO and 315 nm for BPAO). This suggests that π‐electrons of the polymers are extensively delocalized along the main chain.