A theoretical insight into the curing mechanism of phthalonitrile resins promoted by aromatic amines
A theoretical insight into the curing mechanism of phthalonitrile resins promoted by aromatic amines
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DOI：
10.1039/d1cp01947c
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发表时间：
2021-07-27
影响因子：
3.3
通讯作者：
Du, Lei
中科院分区：
文献类型：
--
作者：
Chen, Zuowei;Wang, Liquan;Du, Lei
高温邻苯二甲腈树脂具有广泛的应用，了解其固化机理对于学术研究和工程应用都具有重要意义。然而，实际的固化机制仍然难以捉摸。以邻苯二甲腈和苯胺为模型化合物，对芳香胺促进邻苯二甲腈树脂固化机理进行了密度泛函理论研究。我们发现，速率控制步骤是初始的亲核加成胺与腈基邻苯二甲腈生成脒中间体。在整个固化反应中，胺在H-转移促进剂中起着至关重要的作用。脒和异吲哚啉是重要的中间体，它们可以通过六元过渡态与邻苯二甲腈反应。脒类中间体的分子内环化反应是形成异吲哚啉类中间体的关键步骤，胺类化合物能显著促进环化反应。建议的固化反应途径是动力学上更有利的比以前报道的，这可以占形成三嗪，聚异吲哚啉，酞菁和提供一个分子水平的理解的固化反应。
High-temperature phthalonitrile resins have a wide range of applications, and understanding their curing mechanism is of great importance for academic research and engineering applications. However, the actual curing mechanism is still elusive. We presented a density functional theory study on the curing mechanism of phthalonitrile resins promoted by aromatic amines using phthalonitrile and aniline as the model compounds. We found that the rate-determining step is the initial nucleophilic addition of amines with nitrile groups on phthalonitrile to generate an amidine intermediate. The amines play a vital role in the H-transfer promoter throughout the curing reaction. The amidine and isoindoline are the critical intermediates, which can readily react with phthalonitrile through 6-membered transition states. The intramolecular cyclization of amidine intermediates is the vital step in forming isoindoline intermediates, which can be significantly promoted by amines. The proposed curing reaction pathways are kinetically more favorable than the previously reported ones, which can account for the formation of triazine, polyisoindoline, and phthalocyanine and provide a molecular-level understanding of the curing reaction.