基于2,5-二(4-氨基苯)嘧啶聚酰亚胺的合成及性能表征

1,5-二氮杂戊二烯盐(vinamidium salts)与4-硝基苯甲脒盐在碱性物质的存在下发生成环反应得含嘧啶环的硝基化合物;硝基化合物用Pd/C和水合肼还原得到棒状含氮芳杂环二胺——2,5-二(4-氨基苯基)嘧啶.通过1H-NMR,13C-NMR,IR,MS及元素分析确证了含氮芳杂环二胺及其中间产物的结构.这种二胺或加一定量对苯二胺与均苯二酐(PMDA)或联苯二酐(BPDA)通过两步法聚合获得一系列聚酰亚胺,通过红外、动态力学、静态力学、热重分析、广角X射线衍射等实验测试了该类聚合物的结构、热性能、机械性能及结晶性能.

SYNTHESES AND PROPERTIES OF POLYIMIDES DERIVED FROM 2,5-BIS(4-AMINOPHENYL)PYRIMIDINE

Aromatic diamine 4 containing 2,5-disubstituted pyrimidine structure was synthesized via a condensation reaction of vinamidium salts and amidine chloride salts,followed by hydrazine palladium catalyzed reduction.A series of homo-and co-polyimides containing pyrimidine units were prepared from the diamine and 1,4-phenylenediamine(PDA) with pyromellitic dianhydride(PMDA) or 3,3′,4,4′-biphenyl tertracarboxylic dianhydride(BPDA) via a conventional twostep thermal imidizaton method.All of the polyimides showed excellent thermal stability and mechanical properties.The glass transition temperatures of the resulting polymides are in the range of 280-437℃,and the 5% weight loss temperatures are in the range of 545-588℃ in air.The polyimides films possess strength at break in the range of 185-282 MPa,elongations at break in the range of 9.1%-51% and tensile modulus in the range of 3.5-6.46 GPa.The polymer films are insoluble in common organic solvents exhibiting high chemical resistance.