A series of poly(ester imide)s (PEsIs) were prepared using longitudinally extended structures of ester‐linked tetracarboxylic dianhydrides with different numbers of aromatic rings (N_Ar = 4‐6). In the PEsIs obtained using p‐phenylenediamine (p‐PDA), a clear trend was observed: the water absorption (W_A) decreased with increasing N_Ar. In contrast, no clear decrease in the T_g with increasing N_Ar was observed for the PEsIs obtained using 4,4′‐oxydianiline (4,4′‐ODA). The PEsIs obtained using a methyl‐substituted tetracarboxylic dianhydride (N_Ar = 5) showed more suppressed W_A and higher elongation at break (ε_b) values than those of the nonsubstituted counterparts. The former result is probably closely related to the enhanced crystallinity. However, methyl substitution caused an appreciable reduction in the thermal stability. Thus, the methyl‐substituted PEsIs did not meet the V‐0 standard in the UL‐94V test, unlike the substituent‐free counterparts. The PEsI copolymer obtained using the substituent‐free tetracarboxylic dianhydride (N_Ar = 6) with p‐PDA (75 mol%) and 4,4′‐ODA (25 mol%) had excellent combined properties, ie, a very high T_g (361°C), an ultralow coefficient of thermal expansion (2.2 ppm K⁻¹), an extremely low coefficient of hygroscopic expansion (3.3 ppm/RH%), moderate film ductility (ε_b^max = 23%), a moderate dielectric constant (3.22), and a low tan δ (2.76 × 10⁻³) at 10 GHz in 50% relative humidity. Thus, this PEsI is a promising novel dielectric substrate material for use in the next generation of high‐performance flexible printed circuit boards.

中文翻译：

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具有低热膨胀系数和低吸水率（IV）的聚（酯酰亚胺）：具有纵向延伸结构的酯连接的四羧酸二酐的作用

使用具有不同芳环数的酯连接的四羧酸二酐的纵向延伸结构制备了一系列聚（酯酰亚胺）（PEsIs）（N _Ar = 4-6）。在使用对苯二胺（p -PDA）获得的PEsI中，观察到明显趋势：吸水率（W _A）随着N _Ar的增加而降低。与此相反，在没有明确的降低Ť_克随Ñ_氩观察到的PEsIs使用4,4'-二氨基二苯醚（4,4'-ODA）获得。使用甲基取代的四羧酸二酐（N _Ar= 5）表现出更多的抑制W¯¯_甲和较高的断裂伸长率（ε _b）值比那些未取代的对应物。前一个结果可能与结晶度的提高密切相关。但是，甲基取代导致热稳定性明显降低。因此，与不含取代基的对应物不同，在UL-94V测试中，甲基取代的PEsIs不符合V-0标准。使用不含取代基的四羧酸二酐（N _Ar = 6）与p ‐ PDA（75 mol％）和4,4'-ODA（25 mol％）所获得的PEsI共聚物具有优异的组合性能，即非常高的T _g（361℃），热膨胀系数（2.2 ppm的K的超低系数^-1），吸湿膨胀（3.3 PPM / RH％），中度膜延展性（极低的系数ε _b^最大= 23％），中等电介质常数（3.22），和低的黄褐色δ（2.76×10 ^-3在50％相对湿度在10千兆赫）。因此，这种PEsI是一种有前途的新型介电基板材料，可用于下一代高性能柔性印刷电路板。