Poly (arylene ether nitrile) (PAEN) bearing pendant carboxyl groups integrates the outstanding performances of special thermoplastics with the merit of solubility and has been extensively employed to prepare advanced composites for uses in dielectric and fluorescence field. This study firstly reported the thermal pyrolysis behavior of diphenolic acid (DBA)-based PAEN characterized by TG/DTG, TG-FTIR and TG-MS technique under non-oxidizing gaseous environment. It is found that PAEN showed third-order degradation mechanism: (i) Side chain degradation starts at 350–480 °C in the pentanoic acid moiety and CN groups, resulting in the main pyrolysis products of Ph-CH₂-Ph-O-Ph or Ph-Ph-O-Ph by releasing CH₄, H₂O, HCN, CO, HCHO, CH₃OH, CO₂, HCOOH, C₄H₈. (ii) Main chain pyrolysis was caused by cleavages of CC and CO bond in backbone at 480–650 °C, mainly releasing aromatic compounds including C₆H₆, C₇H₈, C₆H₅OH, C₆H₅OCH₃, etc. (iii) Carbonization happened over 650 °C and finally formed an extended aromatic array of graphite. The obtained results not only help our understanding for the identification, structural determination, and thermal resistance of PAEN materials, but also will guide molecular design of poly arylene ethers with higher thermal durability.

带有羧基侧基的聚（亚芳基醚腈）（PAEN）结合了特殊热塑性塑料的优异性能和溶解性的优点，已被广泛用于制备用于介电和荧光领域的先进复合材料。本研究首次报道了以 TG/DTG、TG-FTIR 和 TG-MS 技术为特征的二酚酸 (DBA) 基 PAEN 在非氧化气体环境下的热裂解行为。发现PAEN表现出三级降解机制：（i）戊酸部分和CN基团的侧链降解开始于350-480°C ，导致Ph-CH ₂ -Ph-O-的主要热解产物Ph 或 Ph-Ph-O-Ph 通过释放 CH ₄、H ₂ O、HCN、CO、HCHO、CH ₃OH、CO ₂、HCOOH、C ₄ H ₈。(ii) 主链热解是由主链中的 C C 和CO 键在 480–650 °C下断裂引起的，主要释放芳香族化合物，包括 C ₆ H ₆、C ₇ H ₈、C ₆ H ₅ OH、C ₆ H ₅ OCH ₃(iii) 碳化发生在 650 °C 以上，最终形成石墨的扩展芳族阵列。获得的结果不仅有助于我们理解PAEN材料的识别、结构确定和耐热性，而且将指导具有更高耐热性的聚亚芳基醚的分子设计。