• Macromolecular Research
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• 제17권12호
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• pp.976-986
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• 2009

With the study goal of firstly elucidating the anisotropic interactions between oriented polymer chain segments and liquid crystal (LC) molecules, and secondly of determining the contributions of the chemical components of the polymer segments to the film surface topography, LC alignment, pretilt, and anchoring energy, we synthesized three dianhydrides, 1,4-bis(4'-t-butylphenyl)pyromellitic dianhydride (BBPD), 1,4-bis(4'-trimethylsilylphenyl)pyromellitic dianhydride(BTPD), and 2,2'-bis(4"-tert-butylphenyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride (BBBPAn), and a series of their organosoluble polyirnides, BBPD-ODA, BBPD-MDA, BBPD-FDA, BTPD-FDA, and BBBPAn-FDA, which contain the diamines 4,4'-oxydianiline (ODA), 4,4'-methylenediamine (MDA), and 4,4'-(hexafluoroisopropylidene)dianiline (FDA). All the polyimides were determined to be positive birefringent polymers, regardless of the chemical components. Although all the rubbed polyimide films exhibited microgrooves which were created by rubbing process, the film surface topography varied depending on the polyimides. In all the rubbed films, the polymer chains were unidirectionally oriented along the rubbing direction. However, the degree of in-plane birefringence in the rubbed film varied depending on the polyimides. The rubbing-aligned polymer chains in the polyimide films effectively induced the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The azimuthal and polar anchoring energies of the LCs ranged from $0.45{\times}10^{-4}\;-\;1.37{\times}10^{-4}\;J/m^2$ and from $0.86{\times}10^{-5}\;-\;4.26{\times}10^{-5}\;J/m^2$, respectively, depending on the polyimides. The pretilt angles of the LCs were in the range $0.10-0.62^{\circ}$. In summary, the soluble aromatic polyimides reported here are promising LC alignment layer candidates for the production of advanced LC display devices.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 추계 총회 및 학술발표회
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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.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1625-1628
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• 2006

Two different negative-type photosensitive polyimides were synthesized and characterized for an application as an interdielectric layer in TFTLCD array. In the case of photocurable polyimides, the photosensitive moiety, 2-HHSP, was synthesized through 3 step reaction, and then was incorporated into side chains of polyimide precursor by post reaction. Optimum compositions of negative-type photocurable polyimde were also formulated. For photopolymerizable polyimides, two novel UV monomers containing imide linkages were prepared. An aqueous alkaline developable polymer matrix was synthesized by free radical copolymerization. A negative photoresist formulation was developed utilizing synthesized UV monomers containing imide linkage, photoinitiator, UV oligomer, and alkali developable polymer matrix. It was found that viaholes with good resolution, high transmittance and thermal resistance could be obtained by photolithographic process utilizing the negative-type photoresist formulations.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.1-2
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• 2003

While aromatic polyimides and polyamides have found widespread use as high performance polymers, the present work addressed the need for organosoluble materials through the use of a hyperbranching scheme. The $AB_2$ monomers were prepared. The $AB_2$ monomers were then polymerized via aromatic fluoride-displacement and Yamazaki reactions to afford the corresponding hydroxyl-terminated hyperbranched polyimides (HT-PAEKI) and amine-terminated hyperbranched polyamides, respectively. HT-FAEKI was then functionalized with allyl and propargyl bromides as well as epichlorohydrin to afford allyl-terminated AT-PAEKI, propargyl-terminated PT-PAEKI, and epoxy (glycidyl)-terminated ET-PAEKI, in that order. All hyperbranched poly(ether-ketone-imide)s were soluble in common organic solvents. AT-PAEKI was blended with a bisphenol-A-based bismaleimide (BFA-BMI) in various weight ratios. Thermal, rheological, and mechanical properties of these blend systems were evaluated. Two characteristic hyperbranched polyamides, which the one has para-electron donating groups to the surface amine groups and the other has para-electron withdrawing groups to the surface amine groups, were selected to compare BMI curing behaviors. The electron rich polymer displayed ordinary Michael addition type exothermic reaction, while electron deficient polymer did display unusual curing behaviors. Based on analytical data, the later system provided the strong evidences to support room temperature curing of BMI by reactive intermediates instead of reactive primary amine groups on the macromolecule surface.

• 공업화학
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• 제17권2호
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• pp.217-222
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• 2006

폴리이미드는 높은 열안정성, 우수한 기계적, 전기적 성질을 가지고 있어 많은 연구가 진행되어 왔지만, 대부분의 유기용매에 불용인 관계로 그 용도가 제한되어 있다. 본 연구에서는 방향족 디아민인 2,2,-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAPAF)와 3,3,-diamino-4,4- dihydroxybyphenyl (HAB)를 사용하고 방향족 디안하이드라이드인 4,4-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), pyromellitic dianhydride (PMDA), 4,4-oxydiphthalic dianhydride (OPDA), 3,3,4,4-benzophenone tetracarboxylic dianhydride (BTDA) 및 3,3,4,4-diphenylsulfone tetracarboxylic dianhydride (DSDA)를 사용하여 가용성 폴리이미드를 합성하였다. 폴리이미드의 성질은 NMR, FR-IR 및 TGA를 이용하여 조사하였으며, 유전상수는 축전용량을 측정하여 계산하였다. 히드록시기를 포함한 폴리이미드와 methacryloyl chloride를 반응시켜 감광성 폴리이미드를 합성하고, photolithography기술을 이용하여 micro-패턴을 형성하였다.

• Macromolecular Research
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• 제12권6호
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• pp.545-552
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• 2004

The long-term stability of sulfonic acid-containing polyimides has been investigated. The hydrolytic degradation of homopolyimide and the block copolyimide comprising $27\;mol\%$ of 2,2'-bis(trifluoromethyl)benzidine and $9\;mol\%$ of m-phenylenediamine (BTFMB27mPl0[7/(3+1)]), was quantified through viscosity measurements and FT-IR spectroscopic analyses. The viscosity decrease with respect to time and the degradation rate were similar. The degrees of degradation with respect to time under ambient conditions and at elevated temperature in water were monitored by FT-IR spectroscopy. A new absorption peak was observed at $1786\;cm^{-1},$ which we corresponds to the presence of anhydride end groups formed by hydrolytic scission of the imide rings.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1167-1168
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• 2004

Polarized ultraviolet irradiation techniques have been developed recently to produce alignment of liquid crystals (LC). Because of the excellent thermal stability and the alignment ablility of polyimides, polyimides has attracted considerable research interest for the photoinduced alignment layer. Hasegawa and Taira confirmed homogeneous alignment of LC by the decompostion of a polyimide induced by lineraly ultra-violet polarized light. It was reported that ultraviolet visible absorption spectra of a polyimide alignment film showed a remarkable change upon irradiation. In this study, we synthesized phthalic polyimide and a naphthalenic polyimide in order to investigate the effect of the polyimide structure. Some difference in terms of the photo-induced molecular orientaion of liquid crystals were observed with the polyimide structure.

• Macromolecular Research
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• 제11권6호
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• pp.458-466
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• 2003

Several copolyimides have been synthesized with different combinations of comonomers in order to study the relationship between conductivity and water insolubility. m-Phenylenediamine (m-PDA), an angled comonomer, was introduced into the polymer backbone to increase water absorption, and resulted in higher proton conductivity. 2,2-bis(trifluoromethyl)benzidine (TFMB) was used as the comonomer to promote water insolubility. There is a good correlation between the water uptake and conductivity of the polyimides. The copolyimides that had high water uptake also generated high proton conductivity. Those polyimides had good mechanical properties. The copolyimides that have 27 mol% of TFMB and 9 mol% of m-PDA have reasonable conductivities and are insoluble in water at 90$^{\circ}C$, even though they have lower conductivities than those of the homopolymer.

• Macromolecular Research
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• 제9권5호
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• pp.247-252
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• 2001

Tricyclic aliphatic dianhydride monomer, tricycle[4.2.2.0]dec-9-ene exo, endo-3,4: 7,8-tetra-carboxylicdianhydride (TCDDA), was synthesized by photochemical reaction and poly(amic acid)s from TCDDA and diamines such as 1,4-bis-(4-aminophenoxy)benzene (BAB), 2,2-bis(4-(4-aminophenoxy) phenyl) propane (BAPP), 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (BAPHF), bis(4-(4-ami-nophenoxy) phenyl)sulfone (BAPS), and 1,4-bis-(4-aminophenoxy)biphenyl (BABP) were prepared. The inherent viscosities of the poly(amic acid)s were between 0.39 and 0.50 dL/g. The poly(amic acid)s were converted to polyimide films by thermal imidization. The glass transition temperatures (T$\_$g/) of the polyimides were in the range of 201-263$\^{C}$. The thermogravimetric analysis (TGA) thermogram of these polyimides showed the temperatures of 5% weight losses between 375 and 393$\^{C}$ in nitrogen atmosphere. To show their utility for image generation, degradations of these polyimides in UV exposure were investigated by UV spectroscopy.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.893-896
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• 2007

A series of new photosensitive polyimides having long alkoxy cinnamate chains were synthesized for liquid crystal (LC) photoalignment material. The polymer after irradiating linearly polarized UV light induced homogeneous and stable LC alignment. The chemical structure of the polymeric material was characterized and their photochemical LC alignment behavior was evaluated.