Synthesis of polyimides and segmented block copolyimides by transimidization

The transimidization reaction has been successfully utilized to prepare a s eries of segmented block copolyimides. The synthesis and polymerization of an AX-type amino imide monomer containing the tetrahydro[5]helicene unit we re accomplished. The AX-type amino imide monomer is stable during isolation and purification, owing to its inert X (e.g., N-pyridyl) group, but yet re adily underwent a self-transimidization reaction and produced polyimide. Be cause of the presence of two reactive ends, such an AX-type polyimide could be incorporated into a series of block copolyimides by reaction with comme rcially available dianhydrides and diamines. All the copolymers showed two distinct glass-transition temperatures, typically around 250 and 430 degree s C. (C) 2000 John Wiley & Sons, Inc.