A new unsymmetrical diamine, 2‐(3‐aminophenoxy)‐6‐(4‐aminophenoxy)benzonitrile (3,4‐APBN), is synthesized via two consecutive S_NAr reactions and the temperature‐dependent reactivity of the fluorides in 2,6‐difluorobenzonitrile, whose first S_NAr reaction occurs at 70 °C and second, at 100 °C, allowing timing control of reaction sequence and circumventing the transetherification side reaction. Thus, a series of polyimides (PIs) is prepared from the polymerization of 3,4‐APBN with five common dianhydrides (6FDA, DSDA, OPDA, BTDA, and PMDA). For comparison, a second series is also prepared from two symmetrical diamines ([2,6‐bis(3‐aminophenoxy)benzonitrile (3,3‐APBN) and 2,6‐bis(4‐aminophenoxy)benzonitrile (4,4‐APBN)] and 6FDA or PMDA. The processability of the poly(amic acids) (PAAs), for the first series is greatly improved since their solution viscosities are much lower than PAAs based on symmetrical diamines. Besides having high glass‐transition temperatures (249–332 °C), and thermal stability [5% weight loss in the range of 505–542 °C (air) and 512–546 °C (nitrogen)], these PIs form tough, transparent and flexible films that have a tensile‐strength range of 82.1–121.3 MPa, elongations‐at‐break of 5.33–9.81%, and tensile moduli of 2.11–2.97 GPa. Their film dielectric constants are 3.08–3.62 at 10 kHz, moderately higher than that (2.92) of analogous PI (CP2) without nitrile groups. Overall, we found that the reduction of structural symmetry in repeat units can improve the polymer processibility as well as increasing their dielectric constants. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4998–5011

中文翻译：

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不对称含苄腈的聚酰亚胺的合成与表征：降粘作用和介电性能

通过两个连续的S _N Ar反应以及氟化物在2中的温度依赖性反应性，合成了一种新的不对称二胺2-（3-氨基苯氧基）-6（4-氨基苯氧基）苄腈（3,4-APBN）。 6-二氟苄腈，其第一个S _NAr反应在70°C时发生，其次在100°C时发生，从而可以控制反应顺序并避免跨醚化副反应。因此，由3,4-APBN与五种常见的二酐（6FDA，DSDA，ODPA，BTDA和PMDA）的聚合反应可制得一系列聚酰亚胺（PI）。为了进行比较，还用两个对称的二胺（[2,6-双（3-氨基苯氧基）苄腈（3,3-APBN）和2,6-双（4-氨基苯氧基）苄腈（4,4- APBN）和6FDA或PMDA。由于其溶液粘度远低于基于对称二胺的PAA，因此第一个系列的聚酰胺酸（PAA）的可加工性得到了极大的改善。 249–332°C）和热稳定性[在505–542°C（空气）和512–546°C（氮气）范围内，重量损失了5％]，这些PI形成坚韧，透明和柔性的薄膜，其拉伸强度范围为82.1–121.3 MPa，断裂伸长率为5.33–9.81％，拉伸模量为2.11–2.97 GPa。在10 kHz时，它们的薄膜介电常数为3.08–3.62，略高于不含腈基的类似PI（CP2）的薄膜介电常数（2.92）。总的来说，我们发现重复单元中结构对称性的降低可以改善聚合物的可加工性并增加其介电常数。©2013 Wiley Periodicals，Inc. J. Polym。科学，A部分：Polym。化学 总的来说，我们发现重复单元中结构对称性的降低可以改善聚合物的可加工性并增加其介电常数。©2013 Wiley Periodicals，Inc. J. Polym。科学，A部分：Polym。化学 总的来说，我们发现重复单元中结构对称性的降低可以改善聚合物的可加工性并增加其介电常数。©2013 Wiley Periodicals，Inc. J. Polym。科学，A部分：Polym。化学2013，51，4998-5011