Synthesis and characterization of new unsaturated polyesters and copolyesters containing azo groups in the main chain

A new interesting class of linear unsaturated polyesters based on dibenzylidenecycloalkanones have been synthesized by interfacial polycondensation of 4,4^′-azodibenzoyl chloride or 3,3^′-azodibenzoyl chloride with: 2,5-bis(p-hydroxybenzylidene)cyclopentanone I, 2,6-bis(p-hydroxybenzylidene)cyclohexanone II, 2,6-divanillylidenecyclohexanone III, or 2,7-bis(p-hydroxybenzylidene)cycloheptanone IV at ambient temperature. The copolyesters are also synthesized from the monomers I, II, III or IV with the diacid chlorides. The resulting polyesters and their copolyesters were characterized by elemental analyses, IR spectroscopy and solubility. Additionally, inherent viscosity of the polyesters in the range 0.32-0.86 dL g⁻¹ and the inherent viscosity of the copolyesters in the range 0.28-0.65 dL g⁻¹ were determined. The UV-visible spectra of certain polymers were measured in m-cresol solution and showed a characteristic absorption band at 435-473 nm due to n-π^* transition. The thermal properties of the polymers were evaluated by thermo gravimetric analysis and differential scanning calorimetry measurements and correlated with their structural units. The crystallinity of some polyesters and copolyesters were tested. In addition, the electrical properties of all polyesters and copolyesters were measured.