Synthesis and morphology control of self-condensable naphthalene-containing polyimide by using reaction-induced crystallization

Poly(2,6-1H-benzo[f]isoindole-1,3(2H)-dione) (PBID), which was a self-condensable naphthalene-containing polyimide, was synthesized as precipitated crystals from 6-amino-3-(ethoxycarbonyl)-2-naphthoic acid and 7-amino-3-(ethoxycarbonyl)-2-naphthoic acid by using reaction-induced crystallization during solution polymerization. The obtained PBID crystals possessed high crystallinity, excellent thermal stability and chemical resistance. They neither exhibited Tg nor Tm under the decomposition temperature. The morphology of the PBID crystals depended on not only the polymerization conditions but also the isomeric structure of the monomer, and the wide variety of the morphology appeared such as rods, plates and lathes. The plate-like crystals had fine protuberances on the surface. Copolymerization of PBID and poly(4-phthalimide) were also examined.