PHOTOINDUCED POLYMERIZATION OF BISIMIDES AS MODELS FOR NEW SOLUBLE SIDE-CHAIN-SUBSTITUTED NEGATIVE-TYPE PHOTOSENSITIVE POLYIMIDES

In this paper, we study the photoinduced polymerization of bisimide mo dels for our new soluble side-chain-substituted negative-type photosen sitive polyimides (PSPI) in order to better understand the polymerizat ion behavior of the latter. These model compounds were cross-linked by UV irradiation in the solid state and in N-methyl-2-pyrrolidinone (NM P) solution. Variations in the molecular structure of the photosensiti ve moieties were explored to change the photosensitivity of models and of polymers. The kinetics of photopolymerization of these bisimide mo dels was investigated by using infrared and UV techniques. The cinnama te and furylacrylate derivatives were found mainly to photodimerize, w hereas the two others, acrylate and methacrylate derivatives, photopol ymerize. Reaction orders of 1.5 and 2.0 were verified in the case of m odels but could not be determined for the polymers, due to the restric tion of mobility of the photosensitive side groups on the polymer chai ns (solid-state irradiation) and also because the cross-linked polymer was no longer soluble in NMP and precipitated as it was formed.