TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The diamine compound is of formula H2N-A-NH2. The acid anhydride is (4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride. The diamine compound is a compound 4,4'-(4,4'-sulfonylbis(4,1-phenylene)bis(oxy))dianiline.A=1,4-phenylene, 1,3-phenylene, -T1-O-T1-, -T1-CH2-T1-, -T1-O-T1-X-T1-O-T1-, -T1-O-T2-O-T1-, -T1-O-T1-O-T1-, -T1-(CH2)s-3-methyl-1,4-phenylene, -T3-T3-, -T1-C(CF3)2-T1-, -T4-(CH2)s-T4-, -T5-(CH2)s-T6-, -T7-(CH2)s-T8-, 1,4-phenylene-diylmethyl, cyclohexane-1,4-diyl, cyclohexane-1,3-diyl, bicyclo(2.2.1)heptane-2,5-diyl, bicyclo(2.2.1)heptane-2,5-diylmethyl, bicyclo(2.2.2)octane-2,5-diyl, bicyclo(2.2.2)octane-2,5-diylmethyl, decahydro-naphthalene-2,6-diyl, octahydro-pentalene-2,5-diyl, -(cyclohexyl-diyl)-R1-(cyclohexyl-diyl), -CH2-(bicyclo(2.2.1)heptyl)-CH2-, -(2-R2-substituted-cyclohexyl-diyl)-(2-R3-substituted cyclohexyl-diyl)-, cyclohexyldiyl or -CH2-cyclohexane-1,3-diyl (tri-substituted on 1,5,5-positions by CH3);T1=1,4-phenylene;T2=1,3-phenylene;T3=2-CF3-1,4-phenylene;T4=2-methyl-1,4-phenylene;T5=1,4-phenylene (substituted on 2-position by (CH2)m-CH3, on 6-position by (CH2)n-CH3);T6=1,4-phenylene (substituted on 2-position by (CH2)p-CH3, on 6-position by (CH2)q-CH3);T7=2,6-dimethyl-1,4-phenylene;T8=2-methyl-1,4-phenylene;X=SO2, -C(CH3)2-, -C(CF3)2- or cyclohexane-1,1-diyl;R1-R3=not defined;s=0-2;m, n, p and q=0 to 18.    TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Preparation of self-crosslinking polyimide involves forming a self-crosslinking molecular dendrimer by mixing an acid anhydride (I) and melamine-based material; forming a self-crosslinking polyamic acid by mixing the self-crosslinking molecular dendrimer, with the acid anhydride (I) and a diamine compound; and forming a self-crosslinking polyimide by imidizing the self-crosslinking polyamic acid (P1). In the step of forming of a self-crosslinking molecular dendrimer, the content of the melamine-based material is 0.0001-0.999 mol based on 1 mol of the acid anhydride (I). In the step of forming of a self-crosslinking polyamic acid, the content of the diamine compound is about 0.001-0.999 mol based on 1 mol of the acid anhydride (I). The self-crosslinking polyamic acid is prepared at a reaction temperature of 0-100 degrees C. The self-crosslinking polyimide is prepared at a reaction temperature of 80-400 degrees C. Preferred Compounds: The polyimide (P2) is a compound of formula (III). The weight average molecular weight of the self-crosslinking polyimide is 10000 to about 200000.n'=1-100000;Z=-(CH2)m'-, -NRR'(CH2)m'-, -(CH2)m'CO-, -CO(CH2)m'-, -O(CH2)m'-, -CO(CH2)m'-, or -OC(CH2)m'-;m'=0-12;R and R'=1-4C alkyl. EXAMPLE - Preparation of self-crosslinking polyimide film (test) was carried out as follows: 0.1 g of melamine was mixed with 20 ml of N-methylpyrrolidone, and the mixture was slowly added to a solution prepared by dissolving 0.714 g of (4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (DTDA) in 30 ml of N-methylpyrrolidone, to form a self-crosslinking molecular dendrimer. The dendrimer (1 equivalent) was added to 1.5433 g of bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS) and was heated at 50 degrees C to form a self-crosslinking polyamic acid. The self-crosslinking polyamic acid was cast without further dilution from NMP on a glass substrate and heated at 50 degrees C for 1 hour to provide a stable film. The resultant structure was treated in a vacuum of 10-1 torr and at 80 degrees C to remove the solvent, and the temperature was increased at a rate of 6 degrees C/minutes to 200 degrees C. The temperature was maintained at 200 degrees C for 10 minutes before being lowered again to 10 degrees C. Then, a polyimide film having a thickness of 80 mu m was exfoliated from the glass substrate using warm water. A control polyimide film was prepared as follows: to a solution in which 1.0288 g of BAPS was dissolved to 20 ml of N-methylpyrrolidone, a solution of 0.714 g of DTDA dissolved in 20 ml of N-methylpyrrolidone was slowly added, and the resultant was heated to a temperature of 50 degrees C to obtain a polyamic acid. Infrared (IR) analysis of the test/control self-crosslinking polyimide was conducted. The test/control polyimide was evaluated for glass transition temperature and maximum decomposition point temperature. The results for test/control were: glass transition temperature (Tg) ( degrees C) = 205.46/180.89; and maximum decomposition point temperature (Td) ( degrees C) = 481.1/461.6. The test self-crosslinking polymer had a lower glass transition temperature and a higher maximum decomposition temperature when compared to control.