SYNTHESIS AND PHOTODEGRADATION OF POSITIVE WORKING POLYIMIDES DERIVEDFROM 2-NITRO-P-XYLYLENEOXYAMINE

Two kind of diamines, 2-nitro-p-xylyleneoxyamine (5a) and p-xylyleneox yamine (5b) were synthesized and used as monomers together with variou s tetracarboxylic dianhydrides to prepare the main-chain photodegradat ive polyimides which exhibited a positive working image upon light irr adiation. The photosensitivities of the polyimides and the viscosities of their precursors on irradiation indicated that the nitro group sub stituted at the ortho position of the benzene ring of the diamine moie ty improved the photolytic decomposability of polymers by at least 1-2 orders of magnitude compared with the hydrogen at the same position. Furthermore, much higher sensitivity was attained by using polyimide f ilms such as 6FDA-5a (polycondensate of 2,2-bis(3,4-dicarboxypheny)hex afluoropropane dianhydride and 5a) and BHTCA-5a (polycondensate of .1] heptane-2-exo,3-exo,5-exo,6-exo-tetracarboxylic 2,3:5,6-dianhydride an d 5a), which contained either a bulky trifluoromethyl (-CF3) substitue nt or a polyalicyclic structure along the polymer backbone. The higher photosensitivities of 6FDA-5a and BHTCA-5a (95 and 85 mJ/cm(2), respe ctively) might be explained by the greater solubilities of the segment s decomposed from these polyimides in development solvent. Therefore, a discussion on the photochemical behavior of polyimides studied was p resented.