• Textile Coloration and Finishing
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• v.7 no.4
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• pp.39-44
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• 1995

A study has been made about some correlations in the chemical cyclization of precursors, poly(ether-amide-amic acid)s by treating in solution a mixture of acetic anhydride and pyridine in the presence of 4,4-dimethyl formamide, with the poly(ether-amic acid)s being respectively reacted between trimellitic anhydride chloride and 3 kinds of diamines, i.e., 4,4'-bis(m-aminophenoxy) benzophenone, 2,2'-bis[4-(m-aminophenoxy) phenyl] propane and 4,4'-bis(m-aminophenoxy) diphenyl sulfone. The cyclization of imide ring in the poly(ether-amide-amic acid)s may be regarded as an intramolecular acylation of amide group by o-carboxyl group. As a result of this reseach, the effects on the conversion to poly(ether-amide-imide)s have been found by changing the ratio of cosolvents in the cyclization mixture.

• Textile Coloration and Finishing
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• v.8 no.2
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• pp.43-48
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• 1996

Condensation type aromatic polyimides were synthesized in DMF solvent by two step low temperature solution polymerization. By employing monomers as p-phenylene 3diamine and 3 kinds of dianhydrides such as pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride and trimellitic anhydride chloride, poly(amic acid) precursors were sythesized. These reactions were exothermic and very fast. When synthesized poly(amic acid)s were dissolved in DMF solvent and stood long time, the polymers were hydrolyzed and their degradation reactions were accelerated as the solution concentrations were dilute. Also, when water is added there-to the degradation rates were accelerated 8faster. In addition, in a very dilute solution state, the reduction viscosity is greatly increased to show properties of conventional polyelectrolytes. This also showed properties sensitive to the concentration change as carboxyl groups per unit segment are increased.

• Proceedings of the Membrane Society of Korea Conference
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• 1999.07a
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• pp.83-86
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• 1999

The imidization effect of a poly (amic acid) dope solution on membrane formation has been investigated. Poly (amic acid) solution in S-methyl-2-pyrrolidione hs been thermally imidized at $120^{\circ}C$ with different curing time and its degree of imidization was determined by infrared spectroscopy. The solution properties have been studied as a function of concentration and curing time by dynamic light scattering. The quality of a solvent was changed from good to poor with increasing imidization of poly(amic acid).The reduced polymer-solvent interaction diminishes the membrane formation time. The morphology of a membrane was able to be controlled by the characteristics of dope solution.

• Polymer(Korea)
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• v.32 no.1
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• pp.77-84
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• 2008

The thermal properties, morphology, mechanical properties and gas permeability of the blends of poly (amic acid) (PAA) and poly (o-hydroxyamides) (PHAs) having pendant group was investigated. The 5% weight loss and major weight loss of the b)ends occurred in the ranges of $348{\sim}407^{\circ}C$ and $589{\sim}615^{\circ}C$ upon a heating process. After a thermical annealing, the tensile strength and initial modulus of blends increased $3.7{\sim}52.9%$ and $34.4{\sim}70%$ from the value of pure PAA, respectively. Especially the tensile strength and modulus of the PAA/MP-PHA=9/1 showed the highest values (97.5 MPa and 2.67 GPa, respectively), which were 53 and 70% higher than those of pure PAA. The fine PHA domains were found to be uniformly dispersed. The interfacial adhesion between PAA and PHA was identified to be good. The gas permeabilities of PAA/M-PHA blend increased with M-PHA contents.

• Proceedings of the Korean Fiber Society Conference
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• 2003.10b
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• pp.130-133
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• 2003

폴리이미드(poly(imide), PI)는 반복 단위 내에 이미드 그룹을 함유하고 있는 고분자로 매우 강한 물리적인 특성을 지니며 열적 및 화학적 안정성이 매우 큰 고분자이다[1-4]. 그러나 이는 대부분이 불용ㆍ불융하기 때문에 프리커서인 poly(amic acid) (PAA) 용액 상태에서 어느 특정한 형태로 가공한 후 열적 혹은 화학적 방법에 의해 이미드 구조로 전환시켜준다. PAA 용액에 사용되는 용매로는 N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethyl-formamide(DMF) 등과 같이 비등점이 높은 극성 용매들이 사용되어진다. (중략)

• 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.

• Macromolecular Research
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• v.9 no.5
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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.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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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.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.317-319
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• 2008

Photo-alignment layer which contains cinnamate is difficult to generate pretilt angle of liquid crystals. In order to enhance pretilt angle, blending poly (amic acid) between containing fluorine poly (amic acid) and 1,2,3,4-cyclobutanetetracaroxylic dianhydride (CBDA) / 3,5-diaminobenzyl alcohol (DBA) were used. For photoreaction, cinnamate was conjugated by interfacial reaction with blending polyimide.

• Elastomers and Composites
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• v.58 no.1
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• pp.26-31
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• 2023

Aromatic diamine containing ortho catenation and methyl group was synthesized from 4-methyl catechol and 4-nitrobenzoyl chloride. Subsequently, a poly(amic acid) was prepared by reacting 4-methyl-1,2-phenylene bis(4-aminobenzoate) with 4,4'-hexafluoroisopropylidenediphthalic anhydride (6FDA). The resulting poly(amic acid) was transformed into a polyimide through chemical imidization. The polyimide formed was soluble in N-methyl-2-pyrrolidone (NMP) and could be cast into a flexible, transparent film. Furthermore, the polyimide exhibited a 5% weight loss at 380 ℃ in the nitrogen atmosphere.