Wholly aromatic polybenzimidazoles were synthesized from aromatic tetraamines and difunctional aromatic acids and characterized as new thermally stable polymers. The melt polycondensation of aromatic tetraamines and the diphenyl esters of aromatic dicarboxylic acids was developed as a general procedure of wide applicability. Polybenzimidazoles containing mixed aromatic units in the chain backbone were prepared from 3,3′-diaminobenzidine, 1,2,4,5-tetraaminobenzene and a variety of aromatic diphenyl dicarboxylates. Phenyl 3,4-diaminobenzoate could also be polymerized by melt condensation to give poly-2,5(6)-benzimidazole. The polymers were characterized by a high degree of stability, showing great resistance to treatment with hydrolytic media and an ability to withstand continued exposure to elevated temperatures. Most of the polymers were infusible, but some had melting points above about 400°C. Many of the polymers exhibited no change in properties on being heated to 550°C. and showed a weight loss of less than 5% when heated under nitrogen for several hours to 600°C. The polymers were soluble in concentrated sulfuric acid and formic acid, producing stable solutions. Many of the polymers were soluble in dimethyl sulfoxide and some also in dimethylformamide. The inherent viscosities of a number of polymers in 0.5% dimethyl sulfoxide solution ranged from approximately 0.4 to 1.1. The higher polymers could be cast into stiff and tough films from formic acid and dimethyl sulfoxide solutions.

中文翻译：

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聚苯并咪唑，新型热稳定聚合物

全芳香聚苯并咪唑由芳香四胺和双官能芳香酸合成，是一种新型的热稳定聚合物。芳族四胺和芳族二羧酸的二苯酯的熔融缩聚被开发为一种具有广泛适用性的通用程序。由 3,3'-二氨基联苯胺、1,2,4,5-四氨基苯和多种芳香族二苯基二羧酸酯制备在链骨架中含有混合芳香单元的聚苯并咪唑。3,4-二氨基苯甲酸苯酯也可以通过熔融缩合聚合得到聚-2,5(6)-苯并咪唑。这些聚合物的特点是高度稳定性，显示出对水解介质处理的极大抵抗力，并能承受持续暴露在高温下。大多数聚合物是不熔的，但有些熔点高于约 400°C。许多聚合物在加热到 550°C 时性能没有变化。在氮气下加热数小时至 600°C 时，重量损失小于 5%。聚合物可溶于浓硫酸和甲酸，产生稳定的溶液。许多聚合物可溶于二甲基亚砜，有些还可溶于二甲基甲酰胺。许多聚合物在 0.5% 二甲亚砜溶液中的特性粘度范围约为 0.4 至 1.1。高级聚合物可以从甲酸和二甲亚砜溶液中浇铸成坚硬而坚韧的薄膜。在氮气下加热数小时至 600°C 时，重量损失小于 5%。聚合物可溶于浓硫酸和甲酸，产生稳定的溶液。许多聚合物可溶于二甲基亚砜，有些还可溶于二甲基甲酰胺。许多聚合物在 0.5% 二甲亚砜溶液中的特性粘度范围约为 0.4 至 1.1。高级聚合物可以从甲酸和二甲亚砜溶液中浇铸成坚硬而坚韧的薄膜。在氮气下加热数小时至 600°C 时，重量损失小于 5%。聚合物可溶于浓硫酸和甲酸，产生稳定的溶液。许多聚合物可溶于二甲基亚砜，有些还可溶于二甲基甲酰胺。许多聚合物在 0.5% 二甲亚砜溶液中的特性粘度范围约为 0.4 至 1.1。高级聚合物可以从甲酸和二甲亚砜溶液中浇铸成坚硬而坚韧的薄膜。