• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.101-101
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• 1993

• Proceedings of the Membrane Society of Korea Conference
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• 1999.04a
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• pp.49-52
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• 1999

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.149.1-149
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• 1998

• Bulletin of the Korean Chemical Society
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• v.22 no.5
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• pp.451-452
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• 2001

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.39-45
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• 1997

Introduction : Polyimides are one of the most important classes of the high performance polymers due to their excellent electrical, thermal, and high-temperature mechanical properties. But their uses are limited because of their poor solubility. Most polyimide derivatives are processed in the form of polyamic acids, which are subsequently converted into the imide structures.Recently, it has been found that the soluble polyimides with large molecular weight sufficient to application. For enhancing processability, the majority of approaches have involved the following factors. As much as, the separation of the imide ring along the back-bone, that is to say, reducing the density of imide ring in the repeat structure. The introduction of bulky substituents along the back-bone, in order to enhance the free volume of main-chain. The incorporation of flexible or thermally stable linkages in the main-chain, reducing the packing force. The disruption of symmetry or recurrence regularity through copolymerization in order to reduce crystallnity.The objectives of this investigation are the synthesis and characterization of soluble polyimides as membrane materials by the single-step polymerization and the preparation of the asymmetric polyimide membrane by using phase inversion technique. In the present study, three series of polyimide derivatives are synthesized; H series is homopolyimides, A series is prepared from single dianhydride and two diamines, B series is yielded from two dianhydrides and a diamine. The dope solution was directly prepared from the PI solution via one step polymerization from monomers.

• Macromolecular Research
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• v.12 no.3
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• pp.263-268
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• 2004

We have synthesized a water-soluble polyimide precursor, poly(amic acid) amine salt (PAD), from pyromellitic dianhydride (PMDA), 4,4'-oxydianiline, and N,N -dimethylethanolamine (DMEA) and have investigated in detail its properties with respect to the degree of salt formation (D$\_$sf/). The maximum value of D$\_$sf/ we obtained upon precipitation of the precursor solution into acetone was 79%. We synthesized a PAD having a D$\_$sf/ of 100% (PAD100) by the solid state drying of an organic solution. The precursors showed different solubility depending on the D$\_$sf/ to make up to 4 wt% solutions in water containing a small amount of DMEA. PAD100 is completely soluble in pure water. We investigated the imidization behavior of PAD in aqueous solution using various spectroscopic methods, which revealed that PAD 100 has faster imidization kinetics relative to that of the poly(amic acid)-type precursors. The resulting polyimide films prepared from an aqueous precursor solution possess almost similar physical and thermal properties as those prepared from N-methyl-2-pyrrolidone(NMP) solution. Therefore, we have demonstrated that PAD can be used as a water-based precursor of polyimide; this procedure avoids the use of toxic organic solvents, such as NMP.

• Proceedings of the Membrane Society of Korea Conference
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• 2001.11a
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• pp.75-78
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• 2001

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.933-934
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• 2002

• Advances in materials Research
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• v.2 no.1
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• pp.51-64
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• 2013

Enantioselective macromer of trimesic acid was prepared using S(-) menthol with trimesoyl chloride on polyimide (PI) ultrafiltration membrane. The chemical composition of macromer as well as polyimide ultrafiltration membrane was determined by ATR-FTIR Spectroscopy. The optical resolution of chiral alcohols was performed in pressure driven process. The effect of monomer solutions concentration, effect of air-drying time of S(-) menthol solution, effect of reaction time, effect of operating pressure, effect of feed concentration of racemate on the performance of macromer was studied. The synthesised material exhibits separation of chiral alcohols (menthol ~23% and sobrelol ~21%).

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.479-482
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• 2002

Benzylideneacetophenones are known as chalcones[1]. The chalcone has been known to be a photo-isomerizable and photo-dimerizable chromophore. The chalcone derivatives were prepared by base-catalyzed condensation of aldehydes and acetophenones, which were substituted with various alkyl chains. The synthesized chalcone was introduced into the t-BOC protected diamine through William synthesis reaction. Photocrosslinkable polyimide was prepared via one-step imidization reaction of DOCDA (5-(2,5-dioxotetrahydro furyl}-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride) and the chalcone introduced diamine using isoquinoline (5 wt%) in m-cresol. The polyimide solutions were spin-coated onto the quartz, silicone wafer and glass substrates and the obtained thin films were irradiated obliquely with linearly polarized UV light.