Thermally stable polymers containing 1,3,4-oxadiazole units obtained from Huisgen reaction

Thermally stable polymers containing 1,3,4-oxadiazole units have been synthesized through Huisgen reaction of the aromatic/aliphatic bis-tetrazole compounds with the aromatic/aliphatic bis-acid chlorides in pyridine as solvent. The obtained polymers are insoluble or slightly soluble even in polar aprotic solvents such as DMSO and DMF. Relatively high inherent viscosity values (0.61–1.33 dL/g, in 0.125% H2SO4 at 25°C) were observed for these compounds. Thermal analyses of the polymers using DSC and TGA techniques showed that the polymers have improved thermal stabilities. The glass transition temperature has not been observed in the fully aromatic polymers, but the polymers obtained from 5-[6-(1H-tetrazol-5-yl)hexyl]-1H-tetrazole (IV) showed very clear Tg. A model reaction was also investigated and the resulting bis-1,3,4-oxadiazole compound was characterized by conventional spectroscopy methods.