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Preparation of organo‐soluble poly[(2,2′‐ m ‐phenylene)‐5,5′‐bibenzimidazole] with high yield by homogeneous nitration reaction
Author(s) -
Lyoo Won Seok,
Choi Jin Hyun,
Han Sung Soo,
Yoon Won Sik,
Park Min Su,
Ji Byung Chul,
Cho Junhan
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/1097-4628(20001010)78:2<438::aid-app240>3.0.co;2-s
Subject(s) - nitration , nitric acid , sulfuric acid , dimethylacetamide , chemistry , polymer chemistry , phenylene , dimethylformamide , yield (engineering) , solubility , nucleophilic substitution , nuclear chemistry , solvent , organic chemistry , materials science , polymer , metallurgy
To prepare organo‐soluble poly[(2,2,′‐ m ‐phenylene)‐5,5′‐bibenzimidazole] (PBI) with high yield, a homogeneous nitration of PBI was attempted. Nitro‐substituted PBI (NO 2 ‐PBI) was synthesized through the homogeneous reaction of the PBI powder with nitric acid in sulfuric acid. The degree of substitution (DS) of this NO 2 ‐PBI is higher than that of the NO 2 ‐PBI prepared through the heterogeneous reaction of the PBI fiber. The viscosity of the NO 2 ‐PBI prepared through the homogeneous reaction decreased with increasing amount of nitric acid added. The DS of the NO 2 ‐PBI reached the maximum value of 2. The substitution efficiency of nitro groups decreased as the amount of nitric acid added increased. When a small quantity of nitric acid was added, the substitution of the sulfonic acid group was confirmed as well as that of the nitro group. The solubility of the NO 2 ‐PBI depended strongly on the DS. The NO 2 ‐PBI having the DS of about 2 was completely soluble in dimethylacetamide and almost soluble in N ‐methylpyrrolidone. At an elevated temperature, it was also soluble in other polar aprotic solvents such as dimethylformamide and dimethylsulfoxide. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 438–445, 2000