• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2311-2316
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• 2010

Three series of copolyterephthalamides having biphenyl-2,2'-diyl structure in the main chain, were synthesized from p-phenylene-containing diamines such as p-phenylene diamine, 4,4'-oxydianiline or 1,4-bis(4-aminophenoxy)benzene, with mixed diacids of terephthalic acid and 2,2'-bibenzoic acid by the direct polycondensation method. The resulting copolymers had inherent viscosities ranging from 0.46 to 0.93dL/g, and most of them could be readily dissolved in polar aprotic solvents including N,N-dimethyl acetamide and N-methyl-2-pyrrolidone. These copolymers had glass transition temperatures between 239 and $326^{\circ}C$, and their 10% weight loss temperatures were recorded in the range of $410{\sim}485^{\circ}C$ in nitrogen atmosphere.

• Journal of the Korean Applied Science and Technology
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• v.27 no.2
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• pp.129-136
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• 2010

A series of noble poly(amide-imide)s and copoly(amide-imide)s bearing 1,2-bis(4-phenoxy)benzene units were synthesized by the direct polycondensation of 1,2-bis(4-trimellitimidophenoxy)benzene[1,2-PTPB] with a combination of commercially available aromatic diamines and diacids such as m-phenylene diamine, p-phenylene diamine(PPD), isophthalic acid and terephthalic acid(TA) in N-methyl-2-pyrrolidone(NMP) using triphenyl phosphite and pyridine as a condensing agent in the presence of dehydrating agent ($CaCl_2$). The resulting polymers had inherent viscosities in the range of 0.37~0.78 dL/g and most of them were soluble m common organic solvents including NMP, dimethylacetamide, dimethylsulfoxide, dimethylformamide, and m-cresol. Wide-angle X-ray diffractograms revealed that the copoly(amide-imide) derived from PPD with mixed acids of 1,2-BTPB and TA, showed crystalline nature, whereas all of the other polymers were found to be amorphous. The glass transition temperatures of the polymers occurred over the temperature range of $270{\sim}323^{\circ}C$ in their differential scanning calorimetry curves and their 10% weight loss temperature, determined by thermogravimetric analysis in air and nitrogen atmosphere, were in the range $465{\sim}535^{\circ}C$, $500{\sim}550^{\circ}C$, respectively, indicating their good thermal stability.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.487-488
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• 2006

Novel bisphenol-based wholly aromatic poly(ether sulfone-ketone) copolymer containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of 4,4-difluorobenzophenone, 2,2'-disodiumsulfonyl-4,4'-fluorophenylsulfone (40mole% of bisphenol A) and bisphenol A. Polymerization proceeded quantitatively to high molecular weight in N-methyl-2-pyrrolidinone at $180^{\circ}C$. Organic-inorganic composite membranes were obtained by mixing organic polymers with hydrophilic $SiO_2$ (ca. 20nm) obtained by sol-gel process. The polymer and a series of composite membranes were studied by FT-IR, $^1HNMR$, differential scanning calorimetry (DSC) and thermal stability. The proton conductivity as a function of temperature decreased as $SiO_2$ content increased, but methanol permeability decreased. The nano composite membranes were found to posse all requisite properties; Ion exchange capacity (1.2meq./g), glass transition temperatures $(164-183\;^{\circ}C)$, and low affinity towards methanol $(4.63-1.08{\times}10^{-7}\;cm^2/S)$.

• Polymer(Korea)
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• v.24 no.3
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• pp.431-436
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• 2000

To improve the thermal and mechanical properties of homo poly(L-lactic acid), DL-mandelic acid, one of the natural $\alpha$-hydroxy acid with aromatic ring as the side-chain residue was used as the comonomer. Copolymers with different contents of mandelic acid were prepared and characterized. The resulting copolymers were mostly amorphous. As the amount of mandelic acid in the monomer feed increased, the molecular weight of the resulting polymers tended to decrease linearly. T$_{g}$ and T$_{d}$ of the copolymer, however, were found to shift toward higher temperature, suggesting the improved thermal stability by increasing content of mandelic acid moiety. Tensile measurements of cast films showed somewhat improved values in the copolymers with mandelic acid content of 5 and 10 wt%.%.%.

• Korean Membrane Journal
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• v.3 no.1
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• pp.9-16
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• 2001

The diamide-diamine having carboxylic acid was prepared by direct condensation of 1,2,4-benzenetricarboxylic acid with bits[4- (3-aminophenoxy ) phenyl] sulfone and bits(4-aminouhenyl)-1,4- diisopropylbenzene in medium consisting of triphenylphosphite, LiCl, and N-methyl-2-pyrrolidone. Copoly (amide-imide) derivatives with high molecular weight could be synthesized by one-step polycondensation of prepared diamide-diamine having carboxylic acid and various dianhydride compounds. Depending on the chemical structure and composition of polymer backbones, the viscosities of polymers were found to range between 0.87∼ 1.57 dL/B. All the polymers showed good thermal stability up to 320$\^{C}$ and the 10% weight loss temperature was observed in the range of 450∼540$\^{C}$ in a thermogravimetric traces. The glass transition was recorded in the temperature range of 200 ∼ 270$\^{C}$. All the polymers showed an amorphous nature on a differential scanning calorimetric thermograms. These polymers generally had good mechanical properties and readily soluble in various polar solvents. Further, it was proved that their properties could be determined from the composition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.575-580
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• 2014

The liquid crystalline copolymers were synthesized through direct polycondensation using 4-[4-(4-hydroxyphenoxy)butoxy]benzoic acid (HBBA) and p-hydroxy benzoic acid (HBA) as monomers. The structure and properties for synthesized copolymers were investigated by $^1H$-NMR, FT-IR, differential scanning calorimetry (DSC), thermogravimetry analysis (TGA) and polarizing optical microscope (POM). As result of investigations, inherent viscosities (${\eta}_{inh}$) of polymers were measured as 0.77~1.60 dL/g in phenol/p-chlorophenol/1,1,2,2-tetrachloroethane (25/40/35=w/w/w). Except for P-80, the ranges of the transition and mesophase temperature of copolymers were increased with increasing the amount of HBA. These properties of polymers were presumably due to increasing of the irregularity and rigidity of polymer chains.

• Bulletin of the Korean Chemical Society
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• v.33 no.10
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• pp.3279-3284
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• 2012

Poly(benzimidazole-co-benzoxazole)s (PBI-co-PBO) are synthesized by polycondensation reaction with 3,3'-diaminobenzidine, terephthalic acid and 3,3'-dihydroxybenzidine or 4,6-diaminoresorcinol in polyphosphoric acid (PPA). All polymer membranes are prepared by the direct casting method (in-situ fabrication). The introduction of benzoxazole units (BO units) into a polymer backbone lowers the basic property and $H_3PO_4$ doping level of the copolymer membranes, resulting in the improvement of mechanical strength. The proton conductivity of $H_3PO_4$ doped PBI-co-PBO membranes decrease as a result of adding amounts of BO units. The maximum tensile strength reaches 4.1 MPa with a 10% molar ratio of BO units in the copolymer. As a result, the $H_3PO_4$ doped PBI-co-PBO membranes could be utilized as alternative proton exchange membranes in high temperature polymer electrolyte fuel cells.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.219-225
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• 2019

Side-chain liquid crystalline polymers with various compositions of azobenzene and cholesteryl functional groups as the mesogenic moiety were synthesized by direct polycondensation, and their properties were investigated. The inherent viscosity values of synthesized polymers were between 0.32 and 0.38 dL/g in 1,1,2,2-tetrachloroethane. All polymers except the SP-A10C0 polymer containing only the azobenzene group were amorphous or exhibited very low crystallinity due to the presence of bulky mesogenic side chains. All synthesized polymers exhibited enantiotropic liquid crystallinity; the SP-A10C0 polymer having only the azobenzene group exhibited a nematic phase, and all other polymers showed a cholesteric phase. In particular, it was found that when the content of cholesteryl groups in the side chain of the polymer increases, the liquid crystallinity decreases due to the bulkiness of cholesteryl groups.

• Elastomers and Composites
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• v.47 no.4
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• pp.355-363
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• 2012

A series of poly(hydroxyamide)s (PHAs) having trifluoromethyl group were prepared by direct polycondensation of aromatic diimide-dicarboxylic acids with 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane by thionyl chloride and triethyl amine in N-methyl-2-pyrrolidinone (NMP). The PHAs exhibited inherent viscosity in the range of 0.54-0.96 dL/g at $35^{\circ}C$ in DMAc solution. All PHAs were readily soluble in a variety of organic solvents, whereas the polybenzoxazoles (PBOs) were quite insoluble except partially soluble in sulfuric acid. PHAs were converted to PBOs by thermal cycling reaction with heat of endotherm. The maximum weight loss temperature of the PHAs occurred in the range of $559-567^{\circ}C$. The PBOs showed relatively high char yields in the range of 47-59%. Pyrolysis Combustion Flow Calorimeter (PCFC) results of the PBOs showed 12-19 W/g heat release rate (HRR), and 2.7-3.6 kJ/g total heat release (total HR). The HRR of PBO 1 showed the lowest value of 12 W/g, which was 37% lower than that of PBO 3 (19 W/g).