Synthesis of thermoplastic–thermosetting merged polyimides by use of the Diels–Alder reaction
作者:Yogesh S. Patel、Hasmukh S. Patel
DOI:10.1007/s11164-013-1389-4
日期:2015.5
Novel thermoplastic–thermosetting merged polyimides (PIs) have been developed by Diels–Alder (DA) intermolecular reaction of the bisfuran 2,5-bis(furan-2-ylmethylcarbamoyl)terephthalic acid A with a series of bismaleimides, viz., m,m′-dimethyl p,p′-dimaleimidobiphenyl (B 1 ), m,m′-dimethoxy p,p′-dimaleimidobiphenyl (B 2 ), 1,1′-bis(4-maleimidophenyl)cyclohexane (B 3 ), and 2,2′-bis-[4-(4-maleimidephenoxy)phenyl]propane (B 4 ). The intermediate DA adducts obtained, C 1–4 , were aromatized and imidized (i.e. cyclized) through the carboxyl and amide groups to afford thermoplastic–thermosetting merged PIs D 1–4 . Bisfuran A was prepared by condensation of pyromellitic dianhydride with furan-2-ylmethanamine and duly characterized. Synthesized DA adducts and PIs were characterized by use of elemental analysis, spectral features, number average molecular weight, degree of polymerization, and thermal analysis. To facilitate the correct structure assignment and to verify the identities of the DA adducts and PIs, a model compound 4 was prepared in a similar way from phthalic anhydride and furan-2-ylmethanamine. FT-IR spectral features of PIs D 1–4 were compared with those of model compound 4 and found to be identical. Glass fiber-reinforced composites GFRC 1–4 were prepared from this system and characterized by chemical, mechanical, and electrical analysis. All the composites had good mechanical, electrical, and thermal properties and good resistance to organic solvents and mineral acids.
通过双呋喃A与一系列双马来酰亚胺(即m,m′-二甲基p,p′-双马来酰亚胺联苯(B 1)、m,m′-二甲氧基p,p′-双马来酰亚胺联苯(B 2)、1,1′-双(4-马来酰亚胺苯基)环己烷(B 3)和2,2′-双-[4-(4-马来酰亚胺苯氧基)苯基]丙烷(B 4))的Diels-Alder(DA)分子间反应,开发了一种新型热塑性-热固性融合聚酰亚胺(PIs)。获得的中间体DA加合物C 1-4通过羧基和酰胺基的芳构化和酰亚胺化(即环化)得到了热塑性-热固性融合PIs D 1-4。双呋喃A是通过均苯四甲酸二酐与呋喃-2-基甲胺的缩合反应制备的,并经过适当表征。合成的DA加合物和PIs通过元素分析、光谱特征、数均分子量、聚合度以及热分析进行了表征。为了便于正确结构分配并验证DA加合物和PIs的身份,通过邻苯二甲酸酐和呋喃-2-基甲胺以类似方式制备了模型化合物4。聚酰亚胺D 1-4的FT-IR光谱特征与模型化合物4的特征进行了比较,发现它们是一致的。从该体系中制备了玻璃纤维增强复合材料GFRC 1-4,并通过化学、机械和电学分析进行了表征。所有复合材料都具有良好的机械、电学和热性能以及良好的有机溶剂和无机酸耐受性。