The mechanism of photocure of inherently photosensitive polyimides containing a benzophenone group

The photochemistry of an appropriately substituted bisimide has been studied in solution by conventional means and time resolved laser techniques as a model for the behavior of inherently photosensitive solvent soluble polyimides, whose photochemistry are not well understood. A mechanism for the photochemical insolubilization of the polymer systems is suggested based on the results for the model system, which is confirmed by time resolved laser studies of polyimide solutions. Phosphorescence quenching rate constants for the model compound indicate that the triplet excited state is about one order of magnitude more reactive than triplet benzophenone, an increase most likely due to the inductive effect of the imide moieties.