Thermal degradation of some [1,3,4]oxadiazole derivatives with liquid crystalline properties

The paper presents the study of thermal degradation of some [1,3,4]oxadiazole Schiff bases with alkyloxy and acyloxy terminal chain. The structure–stability relationship based on TG-MS-FTIR investigations, the degradation processes and the influence of the type of terminal flexible chains upon the thermal and thermal-oxidative stability of 2,5-disubstituted-[1,3,4]oxadiazole derivatives with liquid crystalline properties were investigated. All the investigated compounds presented a very good thermal and thermal-oxidative stability, higher than 330 °C. Thermal stability was investigated both in nitrogen and helium atmosphere. Compounds with alkyloxy terminal chains proved to be more stable than the acyloxy analogous.

► Thermal and thermal-oxidative stability of some new bent core liquid crystals based on a 2,5-disubstituted-[1,3,4]oxadiazole and containing imine and azo-aromatic connecting groups are discussed.
► All 13 compounds presented a very good thermal and thermal-oxidative stability, going up to 3300 C
► TG-MS-FTIR studies evidenced possible beginning of the fragmentation at azo group level.