Based on analysis of the photochemistry of a model compound, N-phenylphthalimide, the photolysis of a polyimide derived from 4,4'-oxydianiline (ODA) and a diarylanhydride with a hexafluorinated isopropylidine bridging group (6F) is proposed to proceed via formation of a phthalic anhydride type photoproduct. The quantum yield for product formation of N-phenylphthalimide is quite low ( < 10- 3) indicating a rather inefficient first step in the overall oxidative degradation process. However, based on the efficiency of the photo-oxidation of the primary photoproducts, a process leading to the ultimate failure and complete ablation of the 6F-ODA films in air upon exposure to the unfiltered output of a mercury lamp is postulated.
Посилання на статтю:
Photodegradation of polyimides: 4. Mechanism for the photo-oxidation process based on a model compound / C. E. Hoyle*, D. Creedt, R. Nagarajan, P. Subramaniant and E. T. Anzures // Polymer. – 1992. – Vol 33. – P. 3162-3168.