• Polymer(Korea)
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• v.29 no.6
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• pp.571-574
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• 2005

The aromatic hyperbranched polyamide was synthesized from 5-aminoisophthalic acid by direct polycondensation with triphenylphosphite (TPP) catalyst as a condensing agent. The modification of end-groups in the resulting hyperbranched polymer (HBP) with various alkyl alcohols were conducted. The modification of end-groups of HBP by alkyl groups resulted in an improved solubility in the THF comparing to that of the carboxylic acid-terminated aromatic HBP, Also, 10 wt$\%$ weight loss temperature decreased by increasing the length of alkyl group.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.578-586
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• 2018

In this study, we prepared the modified PBI random copolymer to reduce the problems of the pristine PBI about low solubility and proton conductivity. The random copolymer was synthesized from suberic acid, 5-aminoisophthalic acid, and 3,3'-diaminobenzidine to obtain $X_1Y_9$, $X_1Y_1$, $X_9Y_1$. Then, the membrane was fabricated by using solvent casting method with methanesulfonic acid at $140^{\circ}C$. Subsequently, the membrane was doped with phosphoric acid at $40^{\circ}C$. The chemical structure of the polymers was characterized by FT-IR. In addition, the physiochemical properties of the PBI were investigated by TGA, oxidative stability, acid uptake. Finally, the proton conductivity was measured at $100-180^{\circ}C$ without humidification. As the result, $X_1Y_9$ PBI random copolymer membrane showed higher conductivity.

• Polymer(Korea)
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• v.35 no.5
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• pp.472-477
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• 2011

To study the effects of the acid group of functionalized MWNT (multiwalled carbon nanotube) on the thermal and mechanical properties of polyacrylonitrile(PAN) nanofibers, acid ($H_2SO_4/HNO_3$) treated MWNT (O-MWNT) were further functionalized by diazonium salt reaction with 5-aminoisophthalic acid (IPA). Compared to O-MWNT, IPA-MWNT with isophthalic acid group showed a better dispersion stability in polar solvents and IPA-MWNT/PAN composite film displayed lower heat of reaction (${\Delta}H$) than that of homo PAN when stabilized under air atmosphere. The continuous electrospun fibers were prepared using a conductive water bath. PAN fibers containing 1 wt% of IPA-MWNT showed an increase of tensile strength by 100% and tensile modulus by 240% compared to the PAN fibers without IPA-MWNT.