Poly[2,6-(1,4-phenylene)-benzobisimidazole] nanofiber networks

The preparation of poly[2,6-(1,4-phenylene)-benzobisimidazole] (PPBI) nanofibers was examined using the crystallization of oligomers during isothermal polymerization of selfpolymerizable 2-(1,4-carbophenoxyphenyl)-5,6- diaminobenzimidazole. The polymerization was carried out at 350 8C at a concentration of 1wt.-% for 6 h in three kinds of solvent. The solvent influenced the morphology of PPBI precipitates significantly, and PPBI nanofiber networks were successfully formed in DBT, of which the width ranged from 30 to 110 nm. Molecules were aligned along the long axis of nanofibers. A fibrillar morphology with molecular orientation is ideal for high performance materials such as reinforcements, non-woven fabrics and so on. The nanofiber networks exhibit the highest thermal stability.