5 Citations (Scopus)

Abstract

Morphology of four kinds of aromatic polyimidazoles was examined by using reaction-induced crystallization during solution polymerization at a concentration of 1% at 350°C in liquid paraffin (LPF), dibenzyltoluene (DBT), and the mixture of these solvents. Aggregates of ribbon-like crystals of poly[2,6-(2,6-naphthalene)-benzobisimidazole] were obtained in LPF, and those of plate-like crystals were obtained in DBT/LPF-50 and in DBT. In contrast to this, the network structures of poly[2,2′-(2,6-naphthalene)-5,5′- bibenzimidazole)] (PNT-BBI) nanofibers with the diameter of 25 to 90 nm was mainly obtained in DBT. The network structures of the PNT-BBI nanofibers could be recognized as nonwoven fabrics of the high-performance polymers. Imidazole trimers were precipitated to form the ribbon-like crystals and then they were continuously supplied from solution to grow the crystals. Molecular weight increased by the polymerization on the surface of the crystals when they crystallized and in the crystals. The initially formed aggregates of ribbon-like crystals changed to the nanofibers with time. In the case of poly[2,6-(4,4′-biphenylene)-benzobisimidazole] and poly[2,2′-(4, 4′-biphenylene)-5,5′-bibenzimidazole)], they exhibited various morphologies such as spheres, lath-like crystals, and the spherical aggregates of lath-like crystals depending on the solvent, but fibers like PNT-BBI were not formed. The crystals obtained in this study possessed very high crystallinity and the outstanding thermal stability measured by TGA.

Original languageEnglish
Pages (from-to)2851-2860
Number of pages10
JournalJournal of Applied Polymer Science
Volume121
Issue number5
DOIs
Publication statusPublished - Sep 5 2011

Keywords

  • crystallization
  • fibers
  • high performance polymers
  • morphology
  • polyimidazole

ASJC Scopus subject areas

  • Chemistry(all)
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry

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