Synthesis of organosoluble aromatic poly(ether ketone)-polyimide copolymers from 9-(4-aminophenyl)-9-(4-hydroxyphenyl)fluorene

9-(4-Aminophenyl)-9-(4-hydroxyphenyl)fluorene reacted with 4,4′-difluorobenzophenone to afford an aromatic ketone-containing aromatic diamine. The aromatic diamine was polymerized with four kinds of tetracarboxylic dianhydrides at room temperature(rt) followed by chemical imidization (Ac2O/NEt3) at 160 °C to afford the corresponding aromatic poly(ether ketone)-polyimide (PEK-PI) alternating copolymers. The resulting PEK-PI copolymers have sufficiently high molecular weights (Mw = 37,600–47,500 or insoluble in all organic solvents), thermal stability (Tg = 269–363 °C) above aromatic poly(ether ketone)s and below aromatic polyimides, and more colorless transparency than typical aromatic poly(ether ketone)s and aromatic polyimides. PEK-PI films, which were fabricated by casting from the CHCl3 solutions, are flexible and free-standing. Hybridization of PEK and PI will lead to the creation of organosoluble (except one PEK-PI), colorless transparent, and thermally stable materials.