TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation of (I) comprises reacting 4-alkyl substituted styrene and alkyl substituted maleic anhydride in the presence of polymerization inhibitor under the catalytic action of nitric oxide gas, adding acetonitrile, dissolving, adding toluene, completely dissolving, cooling and separating the obtained product. Preferred Components: The 4-alkyl substituted styrene is styrene, 4-methylstyrene, 4-ethyl styrene, 4-propyl styrene, 4-iso-butyl styrene, 4-tert-butyl styrene, 4-pentylstyrene, 4-hexylstyrene, 4-heptylstyrene, 4-octylstyrene, 4-nonylstyrene, 4-decylstyrene, 4-undecylstyrene, 4-dodecylstyrene, 4-tridecylstyrene, 4-tetradecylstyrene, 4-pentadecylstyrene or 4-cetylstyrene, preferably 4-methyl styrene. The alkyl-substituted maleic anhydride is maleic anhydride or methyl maleic anhydride, preferably maleic anhydride. The polymerization inhibitor is a phenolic compound. The phenolic compound is hydroquinone, resorcinol, 2-methyl hydroquinone, 2,5-dimethyl-hydroquinone or 2,5-di-tert-butyl hydroquinone, preferably 2,5-di-tert-butyl hydroquinone. The mol ratio of 4-alkyl substituted styrene, alkyl-substituted maleic anhydride and the polymerization inhibitor is 1-2.5:1:0.0005-0.005, preferably 1.5-2:1:0.001-0.002. The reaction temperature is 70-150 degrees C, preferably 90-125 degrees C and the reaction time is 5-20 hours, preferably 10-15 hours. The compound (III) is 4,4'-diaminodiphenyl ether, 1,4-di(4-aminophenoxy)benzene, 2,2-bis(4-(4-aminophenoxy)phenyl)propane or 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane. The solvent is m-cresol, N-methyl pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, cyclopentanone, cyclohexanone, tetrahydrofuran or 1,2-dichloroethane, preferably N-methyl pyrrolidone and N,N-dimethylacetamide. The mol ratio of compound (III), compound (I) and acetic anhydride is 1-1.05:1:1-10, preferably 1-1.02:1:1-5, most preferably 1:1:5. The mol ratio of acetic anhydride and the pyridine is 1:1. The concentration of compound (I) and compound (III) in the reaction system is 5-30 mass.%, preferably 15-20 mass.%, more preferably 20mass.%. The polymerization reaction temperature is 0-50 degrees C, preferably 25-30 degrees C and polymerization reaction time is 5-30 hours, preferably 15-24 hours, more preferably 24 hours. The chemical imidization reaction temperature is 0-50 degrees C, preferably 25-30 degrees C and chemical imidization reaction time is 5-30 hours, preferably 15-24 hours, more preferably 24 hours.