The polyhydroxyamide copolymers (F-PHAs) were synthesized by low-temperature solution polycondensation of 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAHHFP) and/or 3,3′-dihydroxybenzidine (DHB) with terephthaloyl chloride (TPC) in N,N-dimethylacetamide (DMAc) with the aid of lithium chloride (LiCl). A series of polybenzoxazole copolymer (F-PBO) films were fabricated via an efficient solution-casting and thermal-treatment technique, using their precursors (F-PHA films) with different BAHHFP fractions (25-100 mol%). The solubility results show that F-PHAs with higher BAHHFP content (≥75 mol%) are readily soluble in anhydrous DMAc and N-methyl-2-pyrrolidinone (NMP) without LiCl at room temperature. Differential scanning calorimetry (DSC) indicates that the thermal cyclization temperature of the F-PHA films decreases with increasing BAHHFP content. Thermogravimetric analysis (TGA) reveals that the F-PHA and F-PBO films are well prepared and completely converted. The UV-visible spectra indicate that the F-75-PBO film (BAHHFP content: 75 mol%) has reasonable transparency, with 84.9 % transmittance at 600 nm and 397-nm UV cut-off wavelength. It also has lower coefficient of thermal expansion (CTE) (48 ppm/°C) and water absorption (WA) values (0.14%). The BAHHFP as diamine component provides the final F-PBO film with desirable properties, e.g., flexibility, thermal stability, transparency, and WA values.

中文翻译：

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由其前体制备的热稳定聚苯并恶唑共聚物薄膜的制备与表征

通过2,2-双（3-氨基-4-羟基苯基）六氟丙烷（BAHHFP）和/或3,3'-二羟基联苯胺（DHB）与对苯二甲酰氯的低温溶液缩聚反应合成聚羟基酰胺共聚物（F-PHA）借助氯化锂（LiCl）在N，N-二甲基乙酰胺（DMAc）中的三氯甲烷（TPC ）。通过有效的溶液浇铸和热处理技术，使用具有不同BAHHFP分数（25-100 mol％）的前体（F-PHA膜），制备了一系列聚苯并恶唑共聚物（F-PBO）膜。溶解度结果表明，具有较高BAHHFP含量（≥75mol％）的F-PHAs易溶于无水DMAc和N室温下不含LiCl的-甲基-2-吡咯烷酮（NMP）差示扫描量热法（DSC）表明，F-PHA膜的热环化温度随着BAHHFP含量的增加而降低。热重分析（TGA）表明，F-PHA和F-PBO薄膜制备充分，并且已完全转化。紫外可见光谱表明，F-75-PBO膜（BAHHFP含量：75 mol％）具有合理的透明度，在600 nm和397 nm的UV截止波长下具有84.9％的透射率。它还具有较低的热膨胀系数（CTE）（48 ppm /°C）和吸水率（WA）值（0.14％）。作为二胺组分的BAHHFP可为最终的F-PBO膜提供所需的特性，例如柔韧性，热稳定性，透明度和WA值。