Highly phenylated polyimides containing 4,4'-diphenylether moiety

摘要

A new aromatic diamine, 2,2',6,6'-tetraphenyl-4,4'-oxydianiline (4PhODA, 4), has been synthesized by oxidation, bromination, Suzuki coupling and reduction of 4,4'-oxydianiline (4,4'-ODA). Highly phenylated polyimides PI7a-f were prepared from diamine 4 and six commercially available aromatic dianhydrides by one-step method. The inherent viscosity of these polyimides ranged from 0.33 to 0.91 dL/g, measured in a 0.5 g/dL of NMP or m-cresol solution at 30 ℃. These highly phenylated polyimides showed excellent solubility. Especially, polyimide PI7a derived from the rigid pyromellitic dianhydride (PMDA) was soluble in DMAc, NMP at room temperature, and in DMF, chloroform, and m-cresol at 60 ℃. Transparent, flexible and tough films can be obtained by casting from their NMP or m-cresol solutions. They exhibited good thermal stability, except PI7a containing pyromellitic diimide and PI7f containing nathphalenic diimide (T_g ＞ 350 ℃), their glass transition temperatures measured by thermal mechanical analysis (TMA) ranged from 298 to 340 ℃. The decomposition temperatures at 5% weight loss under nitrogen were 506-542 ℃. They also showed excellent mechanical properties. The enhanced solubility combined with good thermal stability could allow these phenylated polyimides to be further functionalized by various aromatic elec-trophilic substitutions on four phenyl rings for polyelectrolyte applications.