• Elastomers and Composites
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• v.54 no.4
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• pp.321-329
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• 2019

A series of poly(hyroxyamide)s (PHAs) was prepared by direct polycondensation reaction of 4,4'-(2,3-pyridinedioxy)dibenzoic acid and/or isophthalic acid with 3,3'-dihydroxybenzidine. The yield percentages of the products were high, and the inherent viscosities of the polymer in DMAc solution at 35℃ were 0.31-0.59 dL/g. All PHA polymers were found to be soluble in polar aprotic solvents such as DMAc, DMSO, NMP, and DMF. On the other hand, LiCl was required to dissolve IPHA-1 in aprotic solvents. Poly(benzoxazole)s (PBOs) were partially soluble in conc-H₂SO₄; IPBO-4, -5, and -6 were partially soluble in NMP only when LiCl was added to the solution, and the solution was heated. The PBO polymers showed a maximum weight loss in the temperature range of 654-680℃, and the char yields at 900℃ under nitrogen atmosphere exceeded 63%.

• Macromolecular Research
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• v.17 no.11
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• pp.901-906
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• 2009

Several aromatic optically active polyamides (PA)s were synthesized from 5-(2-phthalimidiylpropanoylamino)isophthalic acid with various aromatic diamines via direct polycondensation with triphenyl phosphite and pyridine in the presence of calcium chloride and N-methyl-2-pyrrolidone under microwave irradiation and conventional heating conditions. Under the optimized conditions, the reaction mixture was irradiated for 2 min. with a 100% irradiation power (900 W). The resulting polymers were obtained in high yield and moderate inherent viscosity ranging from 0.35 to 0.60 dL/g. All synthesized polymers showed excellent solubility in amide-type solvents. Thermogravimetric analysis revealed a 10% weight loss temperature and char yield at $600^{\circ}C$ in a nitrogen atmosphere of > $350^{\circ}C$ and > 58%, respectively, which suggests that the resulting PAs have good thermal stability.

• Elastomers and Composites
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• v.55 no.3
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• pp.205-214
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• 2020

A series of wholly aromatic polyhyroxyamide (PHA) copolymers were prepared by direct polycondensation reaction of isophthalic acid and diacids containing bulky units with 3,3'-dihydroxybenzidine. The inherent viscosities of the PHAs measured at 35℃ in DMAc solution were in the range of 0.31-0.56 dL/g. The solubility study revealed that the PHAs were readily soluble in aprotic solvents such as, dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP) at room temperature and in less polar solvent such as pyridine. However, the polybenzoxazole (PBO) copoymers were quite insoluble in all organic solvents except partially soluble in concentrated sulfuric acid and partially soluble in NMP containing LiCl. The PBO copolymers showed maximum weight loss temperature in the range of 593-632℃ and high char yields in the range of 65.0-71.2% at 900℃ in a nitrogen atmosphere.