【摘要】 用4,4′-二氨基二苯基甲烷(DDM),3,3′-二羟基联苯胺(HAB),与均苯四甲酸二酐(PMDA)在N,N-二甲基乙酰胺中室温缩聚,制备了3种共聚酰胺酸(CPAA);CPAA膜经热处理失水环化,形成共聚酰亚胺(CPI);在N2气下经500℃热处理,重排转变为DDM-PMDA-HAB唑酰亚胺共聚物(CPB I)。ATR光谱显示了CPI和CPB I膜的特征结构。TGA分析佐证了唑化转变。CPB I膜均显示优良的耐热性(用质量损失5%时的温度Td表示),比相应的CPI高93~138℃;比二元聚合物PMDA-HAB聚苯并唑(PBO)高65~86℃。廉价的DDM在二胺单体中所占摩尔分数为75%时,CPB I仍保持优良的耐热性(Td为573℃)。更多还原

【Abstract】 Three poly(amic acid) copolymers(CPAAs) were synthesized from 4,4′-diamino diphenyl(methane)(DDM),3,3′-dihydroxy-4,4′-diamino-biphenyl(HAB) and pyromellitic dianhydride(PMDA) by condensation in N,N-dimethylacetamide at room temperature.Thermal cyclodehydration of CPAA cast films led to the formation of copolyimides(CPIs),which were rearranged to DDM-PMDA-HAB benzoxazole-imide(copolymers)(CPBIs) by further thermal treatment at 500 ℃ under nitrogen.ATR spectra showed the charac-(teristic) structure of CPIs and CPBIs.TGA analysis confirmed the rearrangement to the formation of Polybenzoxazoles(PBOs).All the CPBI films displayed excellent thermal stability,shown by T_d,the temperature at which the mass loss of the polymer is 5%.T_d values of CPBI films are 93~138 ℃ higher than that of corresponding CPIs,and 65~86 ℃ higher than that of PMDA-HAB PBO.The molar ratio of cheap DDM among diamines can increase up to 75%,while the CPBIs still have the excellent heat resistance(T_d is 573 ℃).更多还原