The pyrazine-based oligomeric phthalonitrile (PN) monomer, 2,6-bis[3-(3,4-dicyanophenoxy)phenoxy]pyrazine (BCPP), was synthesized from the reaction of an excess amount of resorcinol with 2,6-dichloropyrazine in the presence of potassium carbonate, followed by end-capping with 4-nitrophthalonitrile in a two-step, one-pot reaction. 4-(Aminophenoxy)phthalonitrile was applied to promote the curing reaction. The curing behavior was investigated by differential scanning calorimetry and rheological behavior, showing a wide processing window of 94°C, a complex viscosity of less than 1.5 Pa·s and a lower reaction activation energy of 32.57 kJ mol−1. The structure of the BCPP monomer was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The unit cell was determined to be tetragonal system by wide-angle X-ray diffraction. The monomer was cured to yield cross-linked polymers, which exhibited a high initial storage modulus, excellent glass transition temperature, outstanding thermal stability, and low water uptake.

中文翻译：

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吡嗪基低聚邻苯二甲腈树脂的合成及性能

吡嗪基低聚邻苯二甲腈 (PN) 单体 2,6-双[3-(3,4-二氰基苯氧基)苯氧基]吡嗪 (BCPP) 由过量的间苯二酚与 2,6-二氯吡嗪反应合成在碳酸钾存在下，然后在两步一锅反应中用 4-硝基邻苯二甲腈封端。施加4-(氨基苯氧基)邻苯二甲腈以促进固化反应。通过差示扫描量热法和流变行为研究了固化行为，显示了 94°C 的宽加工窗口，小于 1.5 Pa·s 的复数粘度和 32.57 kJ mol-1 的较低反应活化能。通过傅里叶变换红外光谱和核磁共振光谱证实了BCPP单体的结构。通过广角X射线衍射确定晶胞为四方晶系。单体固化后产生交联聚合物，其表现出高初始储能模量、优异的玻璃化转变温度、出色的热稳定性和低吸水率。