吡啶桥联的聚酰亚胺的合成与性能研究

SYNTHESIS AND CHARACTERIZATION OF PYRIDINE-BRIDGED FLUORINATED POLYIMIDES

以3,4-二甲基苯乙酮与3,5-双(三氟甲基)苯甲醛为原料,通过Chichibabin反应制备了吡啶桥联的四甲基化合物,该化合物再经氧化、脱水反应制备了主链含有吡啶环、侧链带有双三氟甲基取代苯侧基的新型含氟芳香族二酐单体,2,6双(3′,4′-二羧基苯基)-4-(3″-,5″-双三氟甲基苯基)吡啶二酐(6FDAPA).FT IR、NMR、质谱以及元素分析等测试结果表明,6FDAPA的结构与预期的相符.利用6FDAPA与另外一种不含氟的二酐单体2,6双(3′,4′二羧基苯基)4苯基吡啶二酐(DAPA)分别与含氟二胺单体,1,4双(2三氟甲基4氨基苯氧基)苯(6FAPB)通过两步热亚胺化法制备了两种聚酰亚胺(PI)薄膜.测试结果表明,6FDAPA6FAPB(PI2)与DAPA6FAPB(PI1)相比具有相近的耐热性能,玻璃化转变温度为280℃,起始热分解温度为580℃、700℃时的重量保持率64.5%.同时PI2具有更为优良的透光性,紫外可见光谱(UV Vis)测试表明,PI2与PI1薄膜在450nm处的透光率分别为85.7%与69.4%.

A fluorinated aromatic pyridine-bridged dianhydride 2, 6-bis （3＇, 4＇-dicarboxyphenyl）-4-（3＂, 5＂- bistrifluorophenyl） pyridine dianhydride （6FDAPA） has been synthesized by the Chichibabin＇ s reaction of 3,4- dimethyl acetophenone and 3, 5-bis （trifluoromethyl） benzaldehyde, followed by oxidization and dehydration reactions. Two polyimide films were prepared by the dianhydride 6FDAPA and the unfluorinated dianhydride 2,6-bis （3＇, 4＇- dicarboxyphenyl） -4- phenyl pyridine dianhydride （ DAPA ） with 1,4-bis （ 4- amino-2-trifluoromethylphenoxy） benzene （6FAPB）, respectively via the two-step polycondensation procedure. The PI-2, derived from 6FDAPA and 6FAPB showed thermal properties similar to those of PI-1, derived from DAPA and 6FAPB. The PI-2 had glass transition temperature of 280℃ and initial thermal decomposition temperature of 580℃. Furthermore, the PI-2 film exhibited higher transparency than that of PI-1 and showed cutoff wavelength of 345 nm and more than 80% of transmittance at 450 nm.