SYNTHESIS OF A PHOTOSENSITIVE POLYIMIDE CONTAINING A DIAZO GROUP AND ITS PHOTO-CROSS-LINKING REACTIONS VIA A LONG-LIVED ACTIVE INTERMEDIATE

A novel intrinsic photosensitive polyimide containing a diazo group in the main chain was prepared, and the quantum yield for the photocross linking reaction was determined to be 0.13 under air at room temperatu re by GPC measurement. The quantum yield for the photo-decomposition r eaction of the diazo group was also determined to be 0.06. These value s are higher by about two orders of magnitude than those for the photo crosslinking reaction of a benzophenone-containing polyimide, which is prepared from benzophenonetetracarboxylic dianhydride (BTDA) and meth ylene bis(2-ethylaniline) (DEDPM). The reaction was found to proceed v ia its singlet excited slate to give a long-lived active intermediate, a carbene, which plays a great role in the increase in the photoreact ivity. Characteristics of the photoreaction and the fluorescence behav ior of a series of imide-substituted diphenyldiazomethanes were also i nvestigated, showing that the reactivity of the diazo groups is not af fected by the existence of charge transfer structures of the Imide gro ups.