A series of co-polyimide (co-PI) resins with distorted noncoplanar structure were carefully designed and successfully fabricated by copolycondensation of 2,3,3′,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxydianiline (ODA), and 4,4′-(1,3-phenylenedioxy)dianiline (TPER). As-introduced asymmetric structure endowed these co-PI resins with excellent solubility and relatively low melt viscosity. Molecular simulation and dielectric analysis confirmed that the distorted noncoplanar structure induced a large amount of free volume. The minimum melt viscosity of co-PI resins decreased with increasing TPER content and reached 520 Pa·s at 400°C, indicative of good processability. Besides, the co-PI resins displayed outstanding thermal performance with glass transition temperature ranging from 256°C to 330°C and 5% weight loss temperature higher than 550°C in nitrogen atmosphere. Moreover, the co-PI sheets prepared by compression molding possessed tensile strength of 79.5–91.7 MPa and bending strength of 71.0–81.2 MPa when tuning the TPER/ODA ratio, with lower strengths observed at higher TPER content.

中文翻译：

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通过掺入 2,3,3',4'-联苯四甲酸二酐制备的热塑性和可溶性共聚酰亚胺树脂

一系列具有扭曲非共面结构的共聚酰亚胺 (co-PI) 树脂经过精心设计并通过 2,3,3',4'-联苯四甲酸二酐、4,4'-氧二苯胺 (ODA) 和 4 ,4'-(1,3-苯二氧基)二苯胺 (TPER)。引入的不对称结构赋予这些 co-PI 树脂优异的溶解性和相对较低的熔体粘度。分子模拟和介电分析证实，扭曲的非共面结构引起了大量的自由体积。co-PI 树脂的最小熔体粘度随着 TPER 含量的增加而降低，在 400°C 时达到 520 Pa·s，表明其具有良好的加工性能。除了，co-PI 树脂表现出出色的热性能，玻璃化转变温度范围为 256°C 至 330°C，在氮气气氛中，5% 的失重温度高于 550°C。此外，当调整 TPER/ODA 比率时，通过压缩成型制备的 co-PI 片材具有 79.5-91.7 MPa 的拉伸强度和 71.0-81.2 MPa 的弯曲强度，在较高的 TPER 含量下观察到较低的强度。