Preparation and properties of polybenzimidazoles containing dibenzothiophenediyl or 5,5-dioxodibenzothiophenediyl units
About: This article is published in Polymer.The article was published on 1981-09-01. It has received 5 citations till now.
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TL;DR: In this paper, a novel aromatic diacid, 3, 5-dicarboxyl-4 0 -amino diphenyl ether, contain- ing pendant phenoxy amine group was synthesized.
Abstract: A novel aromatic diacid, 3, 5-dicarboxyl-4 0 -amino diphenyl ether, contain- ing pendant phenoxy amine group was synthesized. Homo- and co-polybenzimidazoles containing different content of pendant phenoxyamine groups were synthesized by condensation of 3,3 0 -diaminobenzidine with this acid and a mixture of this acid and isophthalic acid in different ratio in polyphosphoric acid. Copolybenzimidazoles with structural variations were also synthesized based on this acid and pyridine dicarbox- ylic acid, terephthalic acid, adipic acid, or sebacic acid. The polymers have good solu- bility in polar aprotic solvents and strong acids and they form tough flexible films by solution casting. The polymers were characterized by different instrumental techni- ques (FTIR, TGA, DSC, XRD, etc.) and for solvent solubility, mechanical properties, inherent viscosity, and proton conductivity. The inherent viscosities of the polymers vary in the range of 0.62-1.52 dL/g. They have high thermal stability up to 475- 506 8C (IDT) in nitrogen, high glass transition temperatures (Tg) ranging from 313 to 435 8C and good tensile strength ranging from 58 to 125 MPa. Proton conductivity of homo polymer is 3.72 3 10 � 3 S/cm at 25 8C and 2.45 3 10 � 2 S/cm at 200 8C V C 2008
51 citations
TL;DR: In this paper, a new dicarboxylic acid was synthesized by direct polycondensation of N-[3,5-bis(5-carboxyly acid-2-benzimidazole) phenyl]phthalimide (1), containing performed benzimide rings and a phthalimide pendent group with various aromatic diamines.
23 citations
TL;DR: In this paper, a model diamide and several polyamides were obtained in an overall yield of (75-90%) by direct polycondensation of acid VII with certain diamines through a phosphorylation reaction at 100-110°C employing a solvent mixture of NMP-pyridine.
Abstract: Novel polyamides containing 2,3,6,7-dibenzo-1-thia-4,5-diazacy-clohepta-2,4,6-triene-4′,4″-dicarboxy-l, l-dioxide (VII) are reported. The acid VII was prepared in several steps from p-chlorobenzoic acid and characterized by spectral data and elemental analysis. Prior to polymer synthesis, a model diamide (MDA) was prepared from VII and p-toluidine. The model diamide and several polyamides were obtained in an overall yield of (75-90%) by direct polycondensation of acid VII with certain diamines through a phosphorylation reaction at 100-110°C employing a solvent mixture of NMP-pyridine. The resulting polyamides and MDA were characterized by spectral, analytical, and thermal methods. The solubility, density, viscosity, and morphology (X-ray) were also studied for the polyamides. These polymers were moderately soluble in conventional polymer solvents, and the inherent viscosities were measured in concentrated sulfuric acid. Integral procedural decomposition temperatures (ipdt) were calculated from th...
4 citations
TL;DR: The polybenzimidazoles containing different contents of pendant nitrophenoxy groups were prepared by condensation of 3,3′-diamino-benzidine with a mixture of 3.5-dicarboxyl-4′-nitro diphenyl ether and isophthalic acid (IPA) in different ratios in polyphosphoric acid as mentioned in this paper.
Abstract: Polybenzimidazoles containing different contents of pendant nitrophenoxy groups were prepared by condensation of 3,3′-diamino-benzidine with a mixture of 3,5-dicarboxyl-4′-nitro diphenyl ether and isophthalic acid (IPA) in different ratios in polyphosphoric acid. The polymers are soluble in polar aprotic solvents, they have inherent viscosities in the range of 0.75–1.10 dL g−1 and they form tough and transparent films on solution casting. They have good thermal stability with initial decomposition temperature ranging from 380 to 416°C in nitrogen, good tensile strength ranging from 56 to 65 MPa and reasonably good oxidative stability. Phosphoric acid uptake of these polymers is low compared with PBI and membranes doped with phosphoric acid exhibit good proton conductivity in the range of 6.6× 10−3 to 1.9× 10−2 S/cm at 25°C and 1.2× 10−2 to 4.9× 10−2 S/cm at 175°C, compared with 3.9× 10−3 S/cm at 25°C and 3.2× 10−2 S/cm at 175°C for PBI. These membranes are suitable for applications as polymer electrolyte for fuel cell and presumably for gas separation at high temperature. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
3 citations
TL;DR: In this paper, the number of nitro groups substituted on the aromatic ring of poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole]s (PBIs) was synthesized by the reaction of PBI with nitric acid in sulfuric acid under various conditions.
Abstract: Nitro-substituted poly[2,2′-(m-phenylene)-5,5′-bibenzimidazole]s (PBIs) were synthesized by the reaction of PBI with nitric acid in sulfuric acid under various conditions. The number of nitro groups substituted on the aromatic ring of PBI per polymeric unit varied from 1.44 to 3.55 according to the reaction conditions. An increase in reaction temperature and concentration of the nitric acid increased the degree of substitution. The inherent viscosity of the substituted polymer increased as the reaction temperature decreased. When the reaction temperature was 30°C, the inherent viscosity of the polymer increased as the concentration of nitric acid increased. The nitro-substituted PBI exhibited polyelectrolyte behavior in formic acid. The nitro groups substituted on PBI were dissociated when the polymer was heated to 450°C, displaying exothermic behavior, and the decomposition of polymer was proportional to its nitro group content. All nitro-substituted PBIs showed better solubilities in polar apro...
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TL;DR: In this paper, the authors surveyed the thermal stability of aromatic-heterocyclic organic polymers and found that polymers containing fused rings were the most stable, while the effect of pendant groups depends on the nature of the group as well as the polymer to which it is bonded.
Abstract: Thermal stability of aromatic-heterocyclic organic polymers is surveyed. Highest stabilities were observed with step ladder (SL) and ladder (L) type polymers. Aliphatics were the most stable. Crosslinking generally results in enhanced stability. The stability of polymers containing fused rings appears to decrease as the number of fused chain segments increases. The effect of pendant groups depends on the nature of the group as well as the polymer to which it is bonded. (FS)
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