• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.343-346
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• 2008

2,2-BIs (3,4-anhydrodicarboxyphenyl)hexafluoropane(6FDA)와 4-aminophenyl sulfone(4APS), 3-aminophenyl sulfone(3APS)를 사용하여 Polyimide(PI)의 전구체인 Poly(amic acid)(PAA)를 합성하였다. 그 후 PAA의 용해도를 측정 하였다. 그리고 PAA에 열을 가하여 PI로 경화됨을 FT-IR을 이용하여 확인 하였다.

• Membrane Journal
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• v.21 no.4
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• pp.307-320
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• 2011

Polymeric gas separation membrane is the fastest growing field in membrane separation process. Polymeric gas separation membrane process is competitive compare to cryogenic process and pressure swing adsorption process. Aromatic polymer materials such as polysulfones, polypheneylene oxides, polycarbonates and polyimides have been used for gas separation. Recently, glassy polymer likes polyimide in aromatic polymers has been developed for achievement of high selectivity and permeability coefficients. The accurate understanding on a type and structure of polymer material is very important, because the factor that polymer material affect gas separation property. In the study, trend and the development direction on synthesis and permeation properties of polyimide is confirmed.

• Membrane Journal
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• v.25 no.2
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• pp.162-170
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• 2015

In this study, gas permeability of polyimide materials having a various amine group was measured and molecular dynamics was used to analyze the dynamic characteristics of the gas molecules in the polyimide by calculating the position and velocity of the gas molecules with change of the time. The gas permeability of polyimide membrane having substitution site which increase free volume in the polymer was increased. However, polyimide with rigid structure showed decreased gas permeability. As a result of analyzing the change in the gas permeation behavior using molecular dynamics simulations, we confirmed that the results show the same tendency with actual measurements of the gas permeability.

• Macromolecular Research
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• v.17 no.10
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• pp.725-728
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• 2009

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.75.2-75.2
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• 2008

• Polymer(Korea)
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• v.29 no.2
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• pp.204-210
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• 2005

We describe a colorless, transparent polyimide films for plastic display substrate which should have heat resistance, roll-to-roll processability and low CTE (coefficient of thermal expansion) property. Colorless polyimides were synthesized from 3,3',4,4'-oxydiphthalic anhydride (ODPA) 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and diamines such as sulfonyldianiline, aminophenoxybenzene (TPE-p, TPE-q, TPE-r) and bis[4-(3-aminophen oxy)phenyl] sulfone (m-BAPS). Their optical properties were measured by UV spectrophotometer, colormeter and hazemeter. We prepared polyimide/organophilic layered silicate nanocomposite to improve dimension stability. These colorless polyimide films showed UV transmittance by the level upper $89\%$, at 440 nm and excellent optical property having the value under yellow index (YI)=7. In addition, polyimide nanocomposite films also showed an improvement of CTE value as decreased according to the amount of layered silicate contents.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.320-326
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• 2013

In this study, various polyimide films were synthesized via low temperature cure in order to understand changes in their physical properties when using 4,4'-oxydianiline (ODA) as a diamine and dianhydride molecules with different backbones on a single diamine such as 4,4'-Oxydiphthalic anhydride (ODPA), 4,4-hexafluoroisopropylidene diphthalic dianhydride (6FDA), and 3,3', 4,4'-benzophenone tetracarboxylic dianhydride (BTDA). After the synthesis of poly(amic acid), polyimide films were fabricated by adding 1,4-diazabicyclo [2.2.2]octane (DABCO), a low-temperature catalyst, at various wt% to poly(amic acid)s. Changes of optical and thermal properties were compared and analyzed between polyimide films without catalyst and polyimide films with catalyst by FT-IR, UV-Vis transmittance, DSC/TGA, and WAXD analysis. Wide-angle X-ray diffraction (WAXD) analysis revealed that the mean intermolecular distance decreased with the use of a catalyst by the type of dianhydride. Thus, while the optical properties of the films improve by a low-temperature cure performed using a catalyst, their thermal properties decrease. These changes can be explained by the changes in the morphological structure of the films triggered by a catalyst-induced reduction in the mean intermolecular distance. Moreover, the results show that the type of dianhydride determines the degree of change in the optical and thermal properties in each types of polyimide, demonstrating that changes in the optical and thermal properties are directly associated with the backbone of the polyimide structure.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.9-14
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• 2022

Silica aerogel is a porous material with a very low density and high specific surface area. Still, its application is limited due to its weak mechanical properties due to structural features. To solve this problem, a method of complexing it with various polymers has been proposed. We synthesized polyimide cross-linked silica aerogel by the sol-gel process to obtain high mechanical properties. Tetraethyl orthosilicate (TEOS) was used as a precursor to make silica aerogel, and 3- aminopropyltriethoxysilane (APTES) was used as a coupling agent for cross-linking polyimide. Polyimide was synthesized using pyromellitic dianhydride and 3,5-diaminobenzoic acid, and mechanical properties were improved by crosslinking polyimide with 10 repeating units in the polyimide chain using the reaction formula ${\frac{n_1}{n_2}}={\frac{n}{n+1}}$ To realize silica aerogel, polyimide having various weight ratios was added before gelation, resulting in a 19-fold or greater increase in maximum compressive strength compared to pure silica aerogel. From this study, an enhancement of silica aerogel could be enhanced through polymer cross-linking bonds.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.83-84
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• 1997

1. INTRODUCTION : Polyimides containing siloxane moiety(poly(imide siloxane), or polysiloxaneimide) have been synthesized because of their some merits over polyimide itseft. Polyimides have excellent thermal and mechanical properties but their poor solubility and processibility in their fullly imidized form give disadvantages in applications. Incorporation of siloxane units make it possible to increase solubility and processibility, and also impart impact resistance, low moisture uptake, low dielectric constant, thermo-oxidative resistance, good adhesion properties to substrate and etc.. Incorporation methods of siloxane groups into the polyimide was mainly copolymerization or terpolymerization between oligomeric dimethylsiloxane and aromatic dianhydride. A few methods of introducing siloxane units in functional groups of polyimide was reported. In our laboratory poly(amideimide siloxane) and poly(imide siloxane) were prepared and the study about their thermal kinetics was performed. In separation membrane area, polysiloxaneimides was utilized in pervaporation and gas separation. Polyimides in gas separation show high selectivity and very low permeability, and introduction of siloxane segments increase permeability with low decrease in selectivity. We aimed to introduce silicone segments into poly(amic acid) state and synthesize polymer partially imidized, and also show the gas separation characteristics of the synthesized polymer.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2049-2056
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• 2014

A simple method for exfoliating pristine graphite to yield mono-, bi-, and multi-layers of graphene sheets as a highly concentrated (5.25 mg/mL) and yielded solution in an organic solvent was developed. Pre-thermal treatment of pristine graphite at $900^{\circ}C$ in a sealed stainless steel bath under high pressures, followed by sonication in 1-methyl-2-pyrrolidinone solvent at elevated temperatures, produced a homogeneous, well-dispersed, and non-oxidized graphene solution with a low defect density. The electrical conductivities of the graphene sheets were very high, up to 848 S/cm. These graphene sheets were used to fabricate graphene-polyimide nanocomposites, which displayed a higher electrical conductivity (1.37 S/m) with an improved tensile strength (95 MPa). The synthesized graphene sheets and nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy.