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

[Display omitted] •Self-condensable polyimides containing naphthalene moiety were synthesized.•Polyimide possessed excellent thermal stability and chemical resistance.•Wide variety of morphologies appeared such as rods, plates and lathes.•Morphology depended polymerization conditions and isomeric structures of monomers. 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.