TECHNOLOGY FOCUS - POLYMERS - Preparation (Disclosed): Preparation of (I) comprises: dissolving a dianhydride monomer of formula (II) in an organic polar solvent (e.g. N-methylpyrrolidone); adding a photosensitive group containing alcohol compound of formula (P1-OH) at 20-90 degrees C to give a dianhydride derivative (III) having one acid group and one ester group; reacting (III) with water to give a tricarboxylic acid compound of formula (G(COOH)3-COOP1) (IV); reacting (IV) with a diamine monomer of formula (H2N-Q-NH2) and optionally an activator (e.g. N,N'-dicyclohexylcarbodiimide) to carry out the polymerization to give (I). Preferred Definitions:    G = phenyl, phenoxy-benzene group, diphenyl-methanone group, biphenyl, trifluoromethyl-phenyl, di(trifluoromethyl)-phenyl, cyclobutyl, napthyl, vinyl-cyclohexa-1,3-dienyl group of formula (d) or diphenyl group of formula (e);    Q = phenyl, 2,2'-dimethyl-biphenyl, phenoxy-benzene group or siloxy group of formula (f) (all preferred), 2,2'-di(trifluromethyl)-biphenyl, 3,3'-dimethyl-biphenyl or diphenyl methane group; and    P1 = CH2=C(CH3)-C(=O)-OC2H4-, CH2=C(H)-C(=O)-OC2H4-, CH2=C(CH3)-C(=O)-OCH2-CH(OH)-CH2- or CH2=C(H)-C(=O)-OCH2-CH(OH)-CH2-.    EXAMPLE - Pyromellitic dianhydride (21.8122 g) was dissolved in N-methyl-2-pyrrolidinone (NMP) (200 g) and heated to 50 degrees C. The mixture was stirred for 2 hours, and then 2-hydroxyethyl methacrylate (13.01 g) was slowly dropped into the mixture at a rate of 1 cc per 10 minute. The temperature was kept at 50 degrees C, and the reaction mixture was stirred for 2 hours, and then purified water (1.8 g) was added to the mixture. After the reaction was stirred for 4 hours, the reaction was cooled to room temperature. 4,4'-Diaminodiphenyl ether (20.02 g) was dissolved in NMP (100 g). After the dissolution was completed, carbic anhydride (0.328 g) was added and the solution was stirred for 1 hour. Then, the two solutions were mixed homogeneously in an ice bath, and then N,N'-dicyclohexylcarbodiimide (41.26 g) was added for conducting a coupling reaction. The temperature was kept at 0 degrees C, the reaction was stirred for 15 hours, and then filtered at a low temperature to give the polymer.