Effect of oxygen on photodegradation of π-conjugated aromatic poly(1,3,4-oxadiazole)s

The effect of oxygen on photodegradation of π-conjugated aromatic poly(1,3,4-oxadiazole)s (POD) was studied in detail. The results obtained by tensile test, UV-spectra and ATR-FTIR revealed that the oxygen was indispensable during photodegradation of POD. The occurrence of photodegradation of POD must be combination of UV exposure and oxygen simultaneously. The state of oxygen during photodegradation of POD was investigated by nitrotetrazolium blue chloride (NBT) method. The result illustrated that the oxygen was transformed into superoxide anion radical through accepting one electron during UV exposure. Results of tensile tests and UV-spectra further proved that the superoxide anion radical could combine with excited POD to form an unstable product that lead to occurrence of photodegradation. Singlet oxygen was also investigated and the result showed that POD appeared to be stable to singlet oxygen.