Novel Soluble Polyimide Containing 4‐ tert‐ Butyltoluene Moiety: Synthesis and Characterization

Based on the synthesis of a rigid aromatic diamine, α , α ‐bis(4‐aminophenyl)‐4‐( t‐ butyl)toluene ( 1 ), a novel polyimide (PI) 3 was prepared from this diamine monomer and 4,4′‐oxydiphthalic dianhydride via a one‐step high‐temperature polycondensation. FT‐IR, 1 H NMR and elemental analysis were used to investigate the chemical structures of 1 and 3 . The results confirmed that they agreed with the proposed structures for both 1 and 3 completely. The obtained PI 3 showed excellent solubility in most common solvents such as N ‐methyl‐2‐pyrrolidinone, N , N ‐dimethylacetamide, N , N ‐dimethylformamide, chloroform, dichloromethane and tetrahydrofuran. The resulting strong and flexible film exhibited high thermal stability with the glass transition temperature at 317°C and the temperature at 10% weight loss beyond 519°C in both air and nitrogen atmospheres. Moreover, the film also showed high optical transparency, low dielectric constant (3.13 at 1 MHz), low water absorption (0.40%) and hydrophobic character.