Photooxidation of amine crosslinked epoxies. II: Influence of structure

We have studied the photooxidation of networks based on three diepoxides containing isopropylidene or methylene bisphenol structures and three diamines of the dianiline type, with, respectively, methylene (DDM), ether (DDE), or sulfone (DDS) bridges. The results are discussed in terms of photoinitiated radical oxidation mechanisms. The comparison of the different systems shows that the photoinitiating species essentially derive from the phenoxy part, whereas the propagation essentially depends on amine concentration and electron density at the nitrogen atom. The amine structure also plays a very important role in color development.