• Proceedings of the Materials Research Society of Korea Conference
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• 1998.08a
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• pp.149.4-149
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• 1998

• Macromolecular Research
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• v.8 no.1
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• pp.19-25
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• 2000

Aromatic diamine monomers containing allylic ester linkage, 1,5-bis(4-aminobenzoate)-1,2,3,4-tetrahydronaphthalene (4-DABTN) and 1,5-bis(3-amin obenzoate)-1,2,3,4-tetrahydronaphthalene (3-DABTN) were synthesized through the reaction of 1,5-dihydroxy-1,2,3,4-tetrahydronaphthalene and 4- or 3-nitrobenzoly chloride. By the reaction of these diamines with pyromellitic dianhydride (PMDA) or 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), poly(amic acid)s were obtained. The inherent viscosities of the poly(amic acid)s were between 0.55 and 1.31 dL/g. The poly(amic acid)s were converted to polyimides by chemical imidization. The thermogravimetric analysis (TGA) thermograms of these polyimides showed temperatures of 5% weight loss between 323 and 389$^{\circ}C$ in nitrogen atmosphere. The model compound ,1,5-bis (4-nitrobenzoate)-1,2,3,4-tetrahydronaphthalene (4-DNBTN), was decomposed to 4-nitrobenzoic acid and 5-(4-nitrobenzoate)-3,4-dihydronaphthalene upon addition of CF$_3$COOH.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1169-1172
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• 2004

Polyimides are blended with photoreactive polymers in order to improve the thermal stability of molecular orientation of photoreactive groups induced by polarized UV irradiation. The polyimide/photopolymer blends can be applied for the photo-induced liquid crystal alignment layers. However, the polyimides are also decomposed by UV irradiation and this may have the negative effect on the orientation of liquid crystals. In order to elucidate the influence of polyimide on the molecular orientation of liquid crystal, non-photoreactive naphthalenic polyimide (1,4,5,8-naphthalene tetracarboxylic dianhydride} was selected for the blend alignment layers. We prepared the blends of photo-reactive coumarin polymers and naphthalenic polyimide, and investigated the orientation of liquid crystals. Thermal stability of the orientation of liquid crystals was enhanced due to the thermally stable polyimide. However, there was no other side-effect of polyimide on the orientation of liquid crystals and this might be attributed to the non-photo-reactivity of naphtahlenic polyimide.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.756-763
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• 1994

Using 2,2-Bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 2,2-bis-[4-(4-aminophenoxy)phenyl] hexafluoropropane and 4,4-diaminodiphenyl ether, the homopolyamic acids, copolyamic acids and blend of homopolyamic acids were prepared and converted to polyimide(PI)s by thermal imidization. In results, it has been found that a exchange reaction of polyamic acids can be occurred during thermal imidization. With measurement of mechanical properties, it was suggested that PI/PI molecular composite can be obtained by copolymerization or physical blending of homopolyamic acids.

• Macromolecular Research
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• v.11 no.3
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• pp.157-162
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• 2003

6FDA-based polyimides were prepared from the thermal imidization reaction of 6FDA with diamines of BAPAF, DAP, and DABA having a polar group of hydroxyL or carboxyl. Properties of the dense polyimide membranes were characterized and their gas permeation properties for H$_2$, $CO_2$, $O_2$, $N_2$, and CH$_4$ were investigated. Permeabilities, diffusion coefficients and diffusivity selectivities of polar group-containing polyimide membranes including 6FDA-BAPAF, 6FDA-DAP, and 6FDA-DABA polymer for the gases did not change largely. The separation properties of 6FDA-TrMPD polyimide membrane used as a reference polymer were compared with those of the polyimide membranes mentioned above. It was found that the polyimides of 6FDA-BAPAF, 6FDA-DAP, and 6FDA-DABA, which were soluble in alcohol or/and 2-methoxyethanol, could be applicable to the preparation of a dense composite membrane by dip-coating method.

• Macromolecular Research
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• v.17 no.9
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• pp.638-645
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• 2009

We report the effect of the amount of the mesoporous material, SBA-15, on the basic traits of fully aliphatic polyimides (API). For this purpose, water soluble, fully aliphatic poly(amic acid) triethyl amine salts ($PAA_{(s)}$) were prepared and mixed with various amounts of SBA-15. Fully aliphatic polyimide hybrid composites containing the SBA 15-type mesoporous silica were synthesized successfully from bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and alicyclic diamine, 4,4'-methylene bis(2-methylcyclohexylamine). The structure of the hybrid composites was confirmed by IR spectroscopic analysis. Scanning electron microscopy revealed the morphology of the compounds. The hybrid composites exhibited good thermal stability, reasonable transparency, and a low dielectric constant.

• Polymer(Korea)
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• v.33 no.3
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• pp.207-212
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• 2009

The precursor polyimide of the photoreactive polyimides(PI-SP6 and PI-SP12) was prepared from a derivative of 2, 2, 2-trifluoroethane dianhydride and 3,3'-dihydroxy-4,4'-diaminobiphenyl. PI-SP6 and PI-SP12 were then prepared by the polymer reactions of the precursor polyimide with photoreactive 2-styrylpyridine alkylene (hexylene and dodecylene) derivatives, respectively. The photoreactive polymers were soluble in organic solvents. The polymers showed the initial decomposition temperatures around $350^{\circ}C$. The glass transition temperatures of PI-SP6 and PI-SP12 were found to be $130^{\circ}C$ and $85^{\circ}C$, respectively. This result means that the latter polymer is more flexible than the former polymer. Their transmittance in the film state was 90% at $250^{\circ}C$, which indicates that the photosensitive polyimides with thermal stability have high optical transparency even at the high temperature. The respective dichroic ratios of PI-SP6 and PI-SP12 were found to be 0.01 and 0.03 at an exposure energy of $1.5\;J/cm^2$. This result suggests that the latter polymer with larger flexibility compared to the former polymer is more effective for the photoalignment.

• Polymer(Korea)
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• v.28 no.4
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• pp.314-320
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• 2004

Soluble aromatic polyimides bearing 4-(4-oxyalkyleneoxystyryl)- pyridines (ethylene and hexylene) as photoreactive side groups were synthesized and characterized. The photoreactive polymers were soluble in various polar organic solvents and their films were easily formed by solution casting. The photoreactivities of the polymers in the film state were approximately 64% at an exposure energy of 1.5 J/$\textrm{cm}^2$. Transmittances of the polymer films were about 85% after annealing at 20$0^{\circ}C$. Therefore, these polymers can be evaluated to be photoreactive polyimides with good transparency and solubility. The dichroic ratios of the polymers with ethylene and hexylene groups as the alkylene spacers were 0.023 and 0.026, respectively. The order parameters of 4'-pentyl-4-bipheny1carbonitrile as a liquid crystal (LC) in the film cells of the former and latter polymers were 0.50 and 0.52, respectively. These results indicate that the polymers show the effect of alkylene spacer on the photoalignments. The LC in the film cells of the polymers was perpendicularly oriented to the electric vector of the linear polarized UV light (LPUVL).

• Proceedings of the Membrane Society of Korea Conference
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• 2003.05a
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• pp.79-83
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• 2003

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.792-795
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• 2006

In-plane-switching (IPS)-mode LCD is one of the most useful technologies for a broad range of viewing angles. To apply for IPS-LCDs, we synthesized novel homogeneous alignment materials, changing dianhydrides (BTDA and BPDA) and bridged diamines (ODA and PACM). We measured their pre-tilt angles using the crystal rotation method with positive LC and their surface properties.