A novel positive-working, photosensitive polyimide, poly[ 1,4-phenyleneoxy1,4-phenylene-2,2'-di(2-nitrobenzyloxy)benzophenone-3,3',4,4'-tetracarboxdiimide] (OPI-Nb), developable with an aqueous base was prepared by the o-nitrobenzylation of a polyimide, poly(1,4-phenyleneoxy-1,4-phenylene-2,2'-dihydroxybenzophenone-3,3',4,-tetracarboxdiimide) (OPI), derived from 2,2'-dihydroxy-3,3,4,4'-benzophenonetetracarboxylic dianhydride (DHBA) and 4,4-oxydianiline, and it micropatterning properties were investigated. The o-nitrobenzylation of OPI to OPI-Nb was conducted with o-nitro-benzyl bromide in N-methyl-2-pyrrolidinone containing Et3N. The DHBA monomer was synthesized by exhaustive KMnO4 oxidation of bis(2-dimethoxy-3,4-dimethylphenyl)methane obtained by etherification of bis(2-hydroxy-3,4-dimethylphenyl)methane with iodomethane, followed by deprotection of the methoxy groups and cyclodehydration of the obtained 2,2-dihydroxy-3,3'4,4'-benzophenonetetracarboxylic acid. The intermediate bis(2-hydroxy-3,4-dimethylphenyl)methane was prepared by the condensation of 2,3-dimethylphenol with paraformaldehyde. The degree of o-nitrobenzylation was determined to be over 94 mol % from H-1 NMR absorption of benzylic CH2 protons. The aromatic OPI was perfectly soluble in a dilute aqueous NaOH solution and tetramethylaramonium. hydroxide (TMAH), whereas OPI-Nb was not even swellable in them. In the micropatterning process, OPI-Nb showed a line-width resolution of 0.4-pra and a sensitivity of 5.4 J/cm(2) when its thin films were irradiated with 365-nm light and developed with a 2.38% aqueous TMAH solution at room temperature for 90 s. The thickness loss of OPI-Nb films measured after postbaking at 350 degrees C was in the 8-9% range. (c) 2007 Wiley Periodicals, Inc.