一类具有高光学透明、高可溶聚酰亚胺薄膜的合成与表征

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。

Synthesis and Characterization of Polyimide with High Solubility and Optical Transparency

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 10wt% 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(Tg) 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.