• Korea-Australia Rheology Journal
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• 제12권1호
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• pp.69-76
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• 2000

We have derived the translation diffusion coefficient and the intrinsic viscosity formula adopting the Kholodenko's theory using 3＋1 dimensional Dirac propagator in the Kirkwood and Riseman scheme. We also performed static light scattering experiments and intrinsic viscosity measurement of dilute solutions of polyimides with different rigidities. In the framework of Kholodenko's theory, we can easily measure the persistence length of polyimide. We prepared five different polyamic acids and polyimides with different degree of imidization by controlling imidization temperatures. From experimental results, we obtained molecular weights and persistence lengths according to the Kholodenko's plot. The molecular weight and the intrinsic viscosity decreased and then increased with the imidization temperature but the persistence length increased monotonically and then leveled off. The persistence lengths calculated from intrinsic viscosities showed very good agreement with those from light scattering experiments.

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.357-362
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• 2003

The pathway producing imide ring closure during the thermal imidization of poly(amic acid) (PAA) was investigated in detail using a new analytical method, two-dimensional (2D) Raman correlation spectroscopy. The signs of the cross peaks in synchronous spectra provided evidence of the thermal imidization of PAA into PI as the heating temperature increased. The signs of the cross peaks in asynchronous spectra suggested that the imide-related modes changed prior to the amide or carboxylic mode, which indicates that cyclization occurred before the amide proton was abstracted.

• Macromolecular Research
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• 제14권1호
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• pp.1-33
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• 2006

Polyimides (PIs) exhibit excellent thermal stability, mechanical, dielectric, and chemical resistance properties due to their heterocyclic imide rings and aromatic rings on the backbone. Due to these advantageous properties, PIs have found diverse applications in industry. Most PIs are insoluble because of the nature of the high chemical resistance. Thus, they are generally used as a soluble precursor polymer, which forms complexes with solvent molecules, and then finally converts to the corresponding polyimides via imidization reaction. This complexation with solvent has caused severe difficulty in the characterization of the precursor polymers. However, significant progress has recently been made on the detailed characterization of PI precursors and their imidization reaction. On the other hand, much research effort has been exerted to reduce the dielectric constant of PIs, as demanded in the microelectronics industry, through chemical modifications, as well as to develop high performance, light-emitting PIs and liquid crystal (LC) alignment layer PIs with both rubbing and rubbing-free processibility, which are desired in the flat-panel display industry. This article reviews this recent research progresses in characterizing PIs and their precursors and in developing low dielectric constant, light-emitting, and LC alignment layer PIs.

• 공업화학
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• 제10권7호
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• pp.979-984
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• 1999

2,2-Bis(3-amino-4-hydroxyphenyl)hexafluoropropane(BAPAF)과 pyromelltic dianhydride(PMDA), 3,3',4,4'-benzophenontetracarboxylic dianhydride(BTDA), 4,4'-(hexafluoroisopropylidene)-bis(phthalic anhydride)(6FDA)을 사용하여 용해성 폴리이드를 합성하였다. 합성된 폴리이미드를 여러가지 유기용제(acetone, NMP, DMAc, DMSO, THF, DMF)를 이용하여 용해성 실험을 행한 결과 열적 이미드화한 경우에는 녹지 않고 팽윤 되었으나 화학적 이미드화한 경우에는 모든 구조가 여러 유기용제에 대해 좋은 용해성을 나타냈다. 이러한 용해도 차이는 화학적 이미드화할 경우 탈수제로 들어간 acetic anhydride에서 나온 $CH_3COO^-$가 하이드록실기와 에스테르 반응을 하여 분자사슬에 결합한데 기인한다. 합성된 폴리이미드의 유리전이온도는 열적 이미드화 경우가 더 높은 값을 나타냈으며 TGA 측정 결과 모든 구조가 $300^{\circ}C$ 이상까지 열적 안정성을 나타내었다. 합성된 폴리이미드의 결정성은 XRD를 이용하여 조사한 결과 모두 무정형으로 나타났다.

• 접착 및 계면
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• 제5권1호
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• pp.29-35
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• 2004

친유기 합성 층상실리케이트(STN)의 함량(1~9 wt%)을 변화하며 폴리아믹산/STN 나노복합재용액을 DMAc 및 THF/MeOH 혼합용매에서 각각 제조하였고, 이를 폴리에스테르 필름에 코팅하여 열적 이미드화 및 화학적 이미드화 반응을 통하여 폴리에스테르/폴리이미드 나노복합필름을 제조하였다. XRD 및 TEM을 이용하여 제조된 폴리에스테르/폴리이미드 나노복합필름의 미세 구조를 조사한 결과 박리형 폴리이미드 나노복합재가 제조되었음을 확인하였다. 표면의 모폴로지 변화는 AFM을 통하여 확인하였으며, 열적 및 기계적 특성은 TGA, DMA와 UTM을 통하여 측정하였다. 또한 STN이 첨가됨에 따라 폴리에스테르/폴리이미드 나노복합필름의 수분투과도는 감소하였고, 화학적 이미드화에 의해 제조된 필름이 열적 이미드화에 의한 필름에 비해 좀더 우수한 수분 차단성을 보였다. 또한 상대적으로 비점이 낮은 THF/MeOH 혼합용매 시스템의 경우가 DMAc를 용매로 사용한 경우보다 더 향상된 수분 차단성을 보였다.

• 공업화학
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• 제3권1호
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• pp.179-187
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• 1992

Poly(styrene-co-maleic anhydride), SMA를 DMF 용매에 약 10%(w/w) 용액으로 한 다음 aniline, p-toluidine 및 p-chloroaniline 등으로 maleic anhydride 반복 단위를 imide화 하였다. 이미드화에 있어서 환화 탈수제(cyclodehydration agents)를 사용하였으며 최적 반응조건은 다음과 같았다. (a) 반응온도 : $80^{\circ}C$ (b) 환화 탈수제의 몰비 : SMA내 anhydride/acetic anhydride/sodium acetate/triethyl amino = 1.0/2.0/0.2/1.1. 생성된 imide-modified SMA (SMI) 시료들은 이미드화도가 증가됨에 따라 $T_g$가 증가하였으나 그 변화 정도는 크지 않았다. SMI의 $T_g$는 이미드화에 사용된 아민의 종류에 따라 aniline < p-toluidine < p-chloroaniline의 순으로 $T_g$가 증가하였다.

• E2M - 전기 전자와 첨단 소재
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• 제9권1호
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• pp.59-66
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• 1996

Polyimides containing cyclobutane ring in main chain is known to be thermally stable and able to be developed in organic solvents after photolysis with 254 nm UV light. This type of polyimides can be used as promising positive photoresist in VLSI fabrication process. In the current VLSI process, photoresist films are formed by spin coating. The film thickness is more than several hundred nano meters. It seems that there is room for improvement of film coating process by introducing Langmuir Blodgett technique. Thereby ultra thin film photoresist can be formed, and higher density of integration in VLSI be achieved. In the present work, depositing procedure of LB films of this polyimide was investigated. LB film thickness was measured by ellipsometry to evaluate deposited film status. Chemical imidization procedure was studied to avoid several problems in thermal imidization. The pattern of submicron dimension has successfully formed on LB film of 8nm thick, which found showing good contrast.

• 한국진공학회지
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• 제1권1호
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• pp.139-144
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• 1992

Ionized Cluster Beam(ICB) 방법을 이용하여 Polyimide(PI) 박막을 증착시켰다. 증 착된 PI 박막의 결정성과 이미드화의 정도를 투과전자현미경(TEM)과 적외선 분광 스펙트럼 (FT-IR)을 이용하여 분석하였다. 최적의 조건에서 증착된 PI 박막은 이미드화가 최대로 증 가하였고 결정구조를 가짐을 관찰할 수 있었다. 이것은 다른 방법으로 제작된 PI 박막과 비 교할 때 훨씬 우수한 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.174-177
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• 1993

The polyimide films were prepared by imidizing the polyamic acid long-chain alkylamine (dimethylhexadecylamine) salt films with a thermal and chemical treatment, where the polyamic acid alkylamine salt film were formed on various substrates by using Langmuir-Blodgett (LB) method. The imidization of polyamic acid alkylamine salt films with various thickness were identified with FT-IR and UV-visible absorption spectroscopies. Atomic Force Microscopy (AFM) have been used to investigate the surface morpology of polyamic acid alkylamine salt and imidized films.

• Macromolecular Research
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• 제10권5호
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• pp.241-245
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• 2002

A new aromatic diamine monomer containing benzoxazole substituents was prepared by a multi-step synthesis starting from 1,4-dibromo-2,5-difluorobenzene. This bulky and disc-shaped monomer was polymerized with commercial dianhydride monomers to give several different poly(amic acid)s with their inherent viscosities in the range of 0.24-0.35 dL/g. The prepared polymers were soluble in typical polar aprotic solvents. Thermal imidization to the corresponding polyimides were investigated by using FT-IR, DSC and TGA.