A high purity diamine monomer, 3,3', 5, 5'-tetramethyl-4,4'-diaminodiphenyl-butyltoluene(BADP), was synthesized via one step from 2, 6-dimethylaniline and benzaldehyde. The obtained diamine was subsequently employed to prepare a series of polyimides with four commercial aromatic dianhydrides. The inherent viscosity of the resulting polyimides were in range of 0. 57~0. 84dL/g, and they exhibited an excellent solubility and optical property. They were readily soluble not only in some strong polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylace-tamide.and N,N-dimethylformamide, but also had a good solubility in some low-boiling-point solvents such as chloroform, tetrahydrofuran, and dichloromethane. The maximum dissolvability of them even exceeded more than l0wt％ in these solvents. The polyimide film showed high optical transparency and colorless, with a UV-vis absorption edge between 341nm and 365nm. Furthermore, the polyimide also showed good thermal and mechanical properties. The temperature of 10% weight loss in air or nitrogen were higher than 440℃ and 500℃ respectively, and their glass-transition temperature(T8) were higher than 333℃. The polyimide films had strengths at break at 62~95MPa, elongations to break of 8. 4%~15. 5%, and initial moduli at 2. 2~3. 5GPa.%以2,6-二甲基苯胺和苯甲醛为原料,经一步合成反应,制得了一种高纯二胺单体α,α-(3,5-二甲基-4-氨基)苯基甲烷(BADP),将其与4种商品化芳香二酐缩聚,制得了一系列主链含3,3',5,5'-四甲基和甲苯基结构的聚酰亚胺,特性黏度在0.57～0.84dL/g之间.该聚酰亚胺表现出优异的溶解性能和光学性能:室温下不仅可以溶于高沸点的NMP、DMAc、DMF和m-Cresol等溶剂中,还能溶于低沸点的CHCl3、CH2Cl2等溶剂中,而且大部分聚合物在这类溶剂中的溶解度可达10％(质量分数)以上；所制得的聚酰亚胺薄膜颜色浅、透明性高,截断波长在341～365nm之间,500nm处的透过率均超过85％.此外,该系列聚酰亚胺还表现出良好的热学性能和力学性能:玻璃化转变温度在333℃以上,空气和氮气中10％热失重在440℃和500℃以上；其薄膜的拉伸强度、断裂伸长率和起始模量分别在62～95MPa、8.4％～15.5％和2.2～3.5GPa之间.
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