含氰基聚酰亚胺的合成

摘要

通过对3,3′,4,4′-联苯四甲酸二酐(BPDA)进行酯化、溴代、氰基取代、水解以及脱水闭环系列反应,合成了侧链含氰基的新型对称二酐——2,2′-二氰基联苯四甲酸二酐,将其与4,4′-二氨基二苯醚(ODA)通过两步法制备了侧链含氰基的聚酰亚胺(PIDC).PIDC的结构与性能由傅里叶变换红外光谱仪、差示扫描量热仪和热重分析仪表征.结果表明:直接由BPDA和ODA通过两步法制备的聚酰亚胺在大多数有机溶剂中不溶,而室温下PIDC在极性非质子溶剂N-甲基吡咯烷酮、二甲基亚砜、N,N-二甲基甲酰胺、N,N-二甲基乙酰胺中溶解性能良好;氰基的引入使聚酰业胺的玻璃化转变温度由266℃增至303℃,氮气氛围下失重5％的温度提高至523℃.%A novel symmetrical 2,2'-dicyano-4,4',5,5'-biphenyl-tetracarboxylic dianhydride (DCBPDA) containing cycano at side chains was synthesized via series of reactions of 3,3',4,4'-biphenyl-tetracarboxylic dianhydride (BPDA), involving esterification, bromination, cycano substitution, hydrolysis and closing-ring dehydration. Cyano-containing polyimide (PIDC) was prepared through polycondensation of DCBPDA with 4,4'-oxydianiline (ODA) in two-step process. The structure and properties of PIDC were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). The results show that the polyimide directly prepared from BPDA and ODA via two-step process is insoluble in majority of organic solvents, while PIDC exhibits excellent solubility in polar aprotic solvents such as yV-methyl-pyrrolidinone, dimethyl sulfoxide, AVV-dimethylformamide, N,N-dimethylacetamide at room temperature. Incorporating cyano groupe makes the polyimide's glass transition temperature rise from 266℃ to 303℃ and temperature of 5% mass loss increases to 523℃ in nitrogen atmosphere.