A novel aromatic diamine monomer with asymmetric large side group: 4-(2,4,6-trimethyl)phenoxy-1,3-diaminobenzene, was synthesized by a two-step organic reaction. The monomer was separately subjected to a one-step high-temperature polycondensation reaction with three commercial aromatic dianhydrides to obtain a series of polyimides. Their structures and properties were characterized and studied by FTIR, NMR, UV, TGA, DSC, etc. The obtained polyimides showed excellent solubility not only in high-boiling solvents such as NMP, DMAc, and DMF, but also in low-boiling solvents such as CHCl 3 and CH 2 Cl 2 . Their tensile strength was in the range of 76.9–93.5 MPa, the elongation at break was between 4.8% and 7.3%, and the modulus of elasticity was in the range of 1.6–1.8 GPa. The obtained films exhibited good optical transparency, and the representative polyimide derived from 4,4′-oxydiphthalic dianhydride exhibited a light transmittance of more than 83% at a wavelength of 450 nm. Moreover, these polyimides also possessed good thermal properties. Their glass transition temperatures are between 285 °C and 345 °C, and the 10% weight loss temperature in air and nitrogen is above 463 °C, showing excellent thermal properties.

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含不对称大侧基的芳族二胺及其聚酰亚胺的合成与表征

通过两步有机反应合成了一种具有不对称大侧基的新型芳族二胺单体：4-(2,4,6-trimethyl)phenoxy-1,3-diaminobenzo。该单体分别与三种市售芳香族二酐进行一步高温缩聚反应，得到一系列聚酰亚胺。通过FTIR、NMR、UV、TGA、DSC等对其结构和性能进行表征和研究。所得聚酰亚胺不仅在NMP、DMAc和DMF等高沸点溶剂中表现出优异的溶解性，而且在低沸点溶剂中也表现出优异的溶解性如CHCl 3 和CH 2 Cl 2 。它们的拉伸强度在 76.9-93.5 MPa 范围内，断裂伸长率在 4.8% 和 7.3% 之间，弹性模量在 1.6-1.8 GPa 范围内。所得薄膜具有良好的透光性，来自4,4'-氧二邻苯二甲酸二酐的代表性聚酰亚胺在450nm波长处的透光率超过83%。此外，这些聚酰亚胺还具有良好的热性能。它们的玻璃化转变温度在285℃～345℃之间，在空气和氮气中10%失重温度在463℃以上，表现出优异的热性能。