1,4-Bis(3,4-dicarboxybenzoyl)benzene dianhydride, an aromatic bis(ketone anhydride) monomer, was synthesized by the Friedel–Crafts reaction of terephthaloyl dichloride and o-xylene, followed by the oxidation of the intermediate tetramethylated compound and cyclodehydration of the resulting tetraacid. A series of new poly(diketone imide)s (PDKIs) were prepared from this dianhydride with various aromatic diamines via a conventional two-stage process that included ring-opening polyaddition to form the poly(amic acid)s followed by thermal or chemical imidization. Most of the PDKIs through chemical imidization were soluble in aprotic amide solvents, such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, m-cresol, and so on. The resulting PDKIs had good thermal property with the glass transition temperature of 203–275°C, the temperature at 5% weight loss of 500–539°C, and the residue of 51–60% at 800°C in nitrogen. Additionally, strong and flexible PDKI films obtained by thermal imidization exhibited outstanding mechanical property with the tensile strength of 88.8–158.5 MPa, tensile modulus of 1.9–3.5 GPa, and elongation at breakage of 7–21%.

中文翻译：

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1,4-双（3,4-二羧基苯甲酰基）苯二酐和各种二胺衍生的新型聚（二酮酰亚胺）的合成与表征

1,4-双（3,4-二羧基苯甲酰基）苯二酐是一种芳香族双（酮酐）单体，通过对苯二甲酰二氯和邻二甲苯的弗瑞德-克来福特反应合成，然后氧化中间体四甲基化化合物和得到的四酸环化脱水。一系列新的聚（二酮酰亚胺）（PDKI）是由这种二酐与各种芳族二胺通过传统的两步法制备的，包括开环加聚以形成聚（酰胺酸），然后进行热或化学酰亚胺化. 大多数经化学酰亚胺化的PDKI可溶于非质子酰胺溶剂，如N,N-二甲基乙酰胺、N-甲基-2-吡咯烷酮、间甲酚等。所得 PDKI 具有良好的热性能，玻璃化转变温度为 203-275°C，5% 失重时的温度为 500–539°C，在 800°C 的氮气中残留 51–60%。此外，通过热酰亚胺化获得的坚固而柔韧的 PDKI 薄膜表现出优异的机械性能，拉伸强度为 88.8-158.5 MPa，拉伸模量为 1.9-3.5 GPa，断裂伸长率为 7-21%。