• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1719-1721
• /
• 1996

This paper describes the thermally stimulated current(TSC) of PAAS spin coated film and the electrical properties of pre TSC measurement and after TSC test specimens. The TSC measurement were performed from room temperature to about $280^{\circ}C$ and the temperature was increased by $5^{\circ}C/min$ automatically. It shows that two peaks of TSC are observed at about $50^{\circ}C$ and about $160^{\circ}C$. Result of this measurement indicate that one peak; $50^{\circ}C$ is from alkyl group; other peak at $160^{\circ}C$ is due to alkyl and C-O group of PAAS. Addition to larger peak at about $160^{\circ}C$ is due to dipolemoment of PAAS film. This result is proved by DSC measurement of PAAS film. The electrical properties of pre and after TSC were measured by currant-voltage(l-V) characteristics. The current-voltage characteristics after TSC specimens are increased the conductivity. The electrical properties of pre-after TSC measurement specimen is in the middle of imidization of PAAS. Because of this result a thermal imidization was performed at $300^{\circ}C$ for 1 hour.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1188-1192
• /
• 2004

Polyamic acid precursors were prepared by mixing various main chain dianhydrides, main chain diamines and side chain diamines. Copolyimide films with alkylcyclohexylbenzene as a side chain were prepared by thermal imidization of polyamic acid precursors. Pretilt angles on rubbed polyimides changed according to the side chain and main chain structures of the polyimide. Consequently, we found that LC pretilt angles of polyimide films with a liquid crystal structure as a side chain showed to be approximately 90$^{\circ}$ when a linear and rigid polyimide main chain and a side chain of suitable length were employed.

• Macromolecular Research
• /
• v.8 no.5
• /
• pp.215-223
• /
• 2000

A novel diamine monomer, containing fluorine and phosphine oxide, bis(3-aminophenyl) 3,5-bis(trifluoromethyl)phenyl phosphine oxide (mDA6FPPO), was prepared via Grignard reaction, and utilized to prepare polyimides with dianhydrides such as PMDA, 6FDA, BTDA or ODPA, by the conventional two-step route; preparation of poly(amic acid), followed by solution imidization. The polyimides were characterized by FT-IR, NMR, and DSC with intrinsic viscosity and refractive index also being evaluated. A phosphine oxide containing monomer, bis(3-aminophenyl)phenyl phosphine oxide (mDAPPO) and a commercial 3,3-diaminodiphenyl sulfone (mDDS) were also used for comparison. The polyimides derived from mDA6FPPO exhibited high T$\sub$g/, excellent solubility and low birefringence.

• Macromolecular Research
• /
• v.15 no.4
• /
• pp.357-362
• /
• 2007

Polyimide/carbon nanotube (CNT) composite films, for potential use in high performance microelectronics and aerospace applications, were prepared by mixing a polyisoimide (PII) solution and a CNT suspension in NMP, followed by casting, evaporation and thermal imidization. The CNTs were modified by a nitric acid treatment to improve the thermal and electrical properties, as well as to provide good dispersion of the CNTs in a polymer matrix. The formation of functional groups on the modified CNT was confirmed by Raman spectroscopy. Scanning electron microscopy revealed the modified CNTs to be well dispersed in the polyimide matrix, with a uniform diameter of ca. 50 nm. The thermal stability of the films containing the CNTs was improved due to the enhanced interfacial interaction and good dispersion between the polyimide matrix and modified CNTs. In addition, the thermal expansion coefficient of the composites films was slightly decreased, but the dielectric constants increased linearly with increasing CNT content.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1992.05a
• /
• pp.6-6
• /
• 1992

Ionized cluster beam deposition (ICBD) technique has been employed to fabricate high-purity crystalline polyimide (PI) film. The pyromellitic dianhydride (PMDA) and oxydianiline (ODA) were deposited using dual ICB sources, Fourier trans forminfraredspectroscopy (FT-IR), X-ray photoemission spectroscopy (XPS), and Transmission electron microscopy (TEM)study show that the bulk and surface chemical properties and the crystalline structure are very sensitive to the ICBD conditions such as cluster ion acceleration voltage and ionization voltage, At optimum ICBD conditions, the PI films have a maximum imidization, negligible impurities(∼1% isoimide), and a good crystalline structure probably due to the high surface migration energy and surface cleaning effect. These characteristics are superior to those of films deposited by other techniques such as colvent cast, vapowr deposition, or sputtering techniques.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.8
• /
• pp.866-870
• /
• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles on thin plastic substrates generated higher than that on glass substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer substrate are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on g1ass.

• Proceedings of the KIEE Conference
• /
• 1998.07d
• /
• pp.1395-1397
• /
• 1998

In this paper, we studied the liquid crystal(LC) alignment and generation of pretilt angle in nematic (N) LC with oblique p-wave polarized ultraviolet (UV) light irradiation on the two kinds of the polyimide (PI) surface. The monodomain alignment of NLC is obtained with oblique p-wave polarized UV light irradiated on PI surface at 5$\sim$60min. We obtained that the pretilt angles of the NLC is generated about $2.1^{\circ}$ with angle of incidence of $30^{\circ}$ at 20min. Also, the pretilt angle of NLC decreases with increasing the imidization temperature on PI surface.

• Proceedings of the KIEE Conference
• /
• 1993.11a
• /
• pp.174-177
• /
• 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
• /
• v.11 no.3
• /
• pp.172-177
• /
• 2003

Biphenyltetracarboximide-phenylene diamine polyimide/silica-titania ternary hybrid composites were Prepared by thermal imidization and sol-gel reaction. Fluorescence spectroscopic, scanning electron microscopy, and atomic force microscopy studies revealed that the addition of small amount of titania showed profound effects on the microstructure and photophysical behaviors of polyimide/silica hybrid composites, when the content of silica-titania mixture was small or when the ratio of silica to titania in the mixture was high.

• Macromolecular Research
• /
• v.10 no.5
• /
• pp.241-245
• /
• 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.