• Title, Summary, Keyword: Polymer precursor

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High Performance Polyimides for Applications in Microelectronics and Flat Panel Displays

  • Ree Moonhor
    • Macromolecular Research
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    • v.14 no.1
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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.

Effect of Polymer Content on Synthesis Process and Microstructure of Alumina-Zirconia Composite (알루미나-지르코니아 복합체의 제조공정 및 미세구조에 미치는 폴리머 첨가의 영향)

  • 이상진;권명도;이충효;조경식
    • Journal of Korean Powder Metallurgy Institute
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    • v.10 no.5
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    • pp.310-317
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    • 2003
  • Two-component ceramic (alumina-zirconia) composites were fabricated by a soft-solution process in which polyethylene glycol (PEG) was used as a polymeric carrier. Metal salts and PEG were dissolved in ethyl alcohol without any precipitation in 1:1 volume ratio of alumina and zirconia. In the non-aqueous system, the flammable solvent made explosive, exothermic reaction during drying process. The reaction resulted in formation of volume expanded, porous precursor powders by a vigorous decomposition of organic components in the precursor sol. The PEG content affected the grain size of sintered composites as well as the morphology of precursor powders. The difference of microstructure in sintered composite was attribute to the solubility and homogeneity of metal cations in precursor sol. At the optimum amount of the PEG polymer, the metal ions were dispersed effectively in solution and a homogeneous polymeric network was formed. It made less agglomerated particles in the precursor sol and affected on uniform grain size in sintered composite.

Photochromic Polysiloxanes Substituted with 1,2-Bis(2-methyIbenzo[b]thiophene-3-yl)hexafluorocyclopentene

  • Shin, Hee-Won;Kim, Yong-Rok;Kim, Eun-Kyoung
    • Macromolecular Research
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    • v.13 no.4
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    • pp.321-326
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    • 2005
  • Photochromic diarylethene polymers (DPs) in which 1,2-bis(2-methylbenzo[b ]thiophene-3-yl)hexafluorocyclopentene (BTF6) were covalently grafted onto the polymer main chain as pendant photochromic units were newly synthesized and their photochromic properties were investigated using steady-state and picosecond timeresolved spectroscopies. Polysiloxanes substituted with BTF6 molecules were prepared by sol-gel process using a mixture of tetraethoxysilane (TEOS), a silylated BTF6, and an organically modified silane precursor in the presence of HCl. The polysiloxane film (DP1) prepared from $\omega-methoxy$ poly(ethylene glycol) 3-(triethoxysilyl) propylcarbainate (MPGSC) as the silane precursor showed a much lower glass transition temperature than that (DP2) from heptadecafluorodecyltrimethoxysilane (HDFTMS). The ring-closure quantum yields of DP1 and DP2 were determined to be 0.20 and 0.02, respectively. Such a large difference in the quantum yield was attributed to the polymer matrix environment of the free inner volume.

Synthesis of N-doped Ethylcyclohexane Plasma Polymer Thin Films with Controlled Ammonia Flow Rate by PECVD Method

  • Seo, Hyunjin;Cho, Sang-Jin;Boo, Jin-Hyo
    • Applied Science and Convergence Technology
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    • v.23 no.1
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    • pp.44-47
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    • 2014
  • In this study, we investigated the basic properties of N-doped ethylcyclohexene plasma polymer thin films that deposited by radio frequency (13.56 MHz) plasma-enhanced chemical vapor deposition (PECVD) method with controlled ammonia flow rate. Ethylcyclohexene was used as organic precursor with hydrogen gas as the precursor bubbler gas. Additionally, ammonia ($NH_3$) gas was used as nitrogen dopant. The as-grown polymerized thin films were analyzed using ellipsometry, Fourier-transform infrared [FT-IR] spectroscopy, UV-Visible spectroscopy, and water contact angle measurement. We found that with increasing plasma power, film thickness is gradually increased while optical transmittance is drastically decreased. However, under the same plasma condition, water contact angle is decreased with increasing $NH_3$ flow rate. The FT-IR spectra showed that the N-doped ethylcyclohexene plasma polymer films were completely fragmented and polymerized from ethylcyclohexane.

Dielectric Properties of Semi-IPN Poly(phenylene oxide) Blend/$BaTiO_3$ Composites with Type of Cross-linker (가교체 종류에 따른 Semi-IPN Poly(phenylene oxide) 블렌드와 $BaTiO_3$ 복합재료의 유전특성)

  • Jang, Yong-Kyun;Lee, Ho-Il;Seong, Won-Mo;Park, Sang-Hoon;Yoon, Ho-Gyu
    • Polymer(Korea)
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    • v.33 no.3
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    • pp.224-229
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    • 2009
  • The dielectric properties of semi-IPN poly(phenylene oxide)(PPO) blend/$BaTiO_3$(BT) composites are investigated. The composites are fabricated via melt-mixing of crosslinker and peroxide in precursor PPO composite obtained by precipitating the suspension consisted of PPO, BT and toluene into methylethyl ketone, poor solvent of PPO. The permittivity of the precursor PPO composites shows higher value than that of integral-blended PPO composites by extruder and coincides with the theoretical value calculated by logarithmic rule of mixture. The blend of PPO and cross-linked triallyl isocyanurate is most effective for lowering the permittivity and loss tangent owing to the suppression of the orientation polarization of matrix. In contrast, 4,4'-(1,3-phenylene diisopropylidene) bisaniline, which has amine unit in its structure, increases the permittivity as well as loss tangent of the composite, but it has the ability to densify the matrix resin and the interfacial adhesion between the matrix and filler to improves flexural strength and modulus.

Characteristics of Porous YAG Powders Fabricated by PVA Polymer Solution Technique

  • Lee, S.J.;Shin, P.W.;Kim, J.W.;Chun, S.Y.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • pp.438-439
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    • 2006
  • Pure and stable YAG $(Y_3Al_5O_{12})$ powders were synthesized by a PVA (polyvinyl alcohol) polymer solution technique. PVA was used as an organic carrier for the precursor ceramic gel. The precursor gels were crystallized to YAG at relatively a low temperature of $900\;^{\circ}C$. The synthesized powders, which have nano-sized primary particles, were soft and porous, and the porous powders were ground to sub-micron size by a simple ball milling process. The ball-milled powders were densified to 94% relative density at $1500\;^{\circ}C$ for 1h. In this study, the characteristics of the synthesized YAG powders were examined.

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Hydroxy-Substituted Polyenaminonitrile as a Soluble Precursor for Rigid-Rod Polybenzoxazole

  • Kim, Ji Heung;Lee, Jae Gwan
    • Bulletin of the Korean Chemical Society
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    • v.22 no.9
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    • pp.999-1004
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    • 2001
  • (1-Chloro-2,2-dicyanovinyl)benzene or 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene was reacted with 2-amino-phenol to give the model compound, hydroxy enaminonitrile, which was found to undergo thermal cyclization reaction to form the corresponding benzoxazole. This intramolecular cyclization reaction is expected to occur through nucleophilic attack to electropositive enamine carbon by ortho-hydroxy group on the phenyl ring, which is accompanied by the release of neutral malononitrile through rearrangement. From each bifunctional monomer, o-hydroxy substituted polyenaminonitrile was prepared and characterized as a new precursor polymer for well-known aromatic polybenzoxazole. Also the unusual macrocyclic dimer formation from the 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane polymerization reaction system was discussed. The thermal cyclization reactions and the properties of polymers were investigated using FT-IR and thermal analysis (DSC & TGA).

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Studies on the Stabilization of Rayon Fabrics for Preparing Carbon Fabrics: 2. Fast Isothermal Stabilization Processes at High Temperature

  • Yoon, Sung-Bong;Cho, Chae-Wook;Cho, Dong-Hwan;Park, Jong-Kyoo;Lee, Jae-Yeol
    • Carbon letters
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    • v.9 no.4
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    • pp.308-315
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    • 2008
  • In the present study, fast isothermal stabilization processes for rayon precursor fabrics were performed at $350^{\circ}C$ and $400^{\circ}C$ within 3 minutes and the chemical and physical characteristics of the stabilized fabrics were investigated. In addition, rayon precursor fabrics were pre-treated with three different phosphorous-based flame retardants and then stabilized. The effect of flame retardants on the chemical composition, thermal shrinkage, weight change, thermal stability and XRD results was examined, comparing with those of the precursor fabrics. The result showed that the stabilization of rayon fabrics was most effective as the stabilization temperature was $350^{\circ}C$, the stabilization time was 3 min, and the pre-treatment with phosphoric acid of 1 vol%. The carbon contents of stabilized rayon fabrics were increased with increasing stabilization temperature and time, whereas the oxygen contents were decreased. Also, it is likely that the pre-treatment with phosphoric acid plays a role in retarding the change of chemical structure of rayon fabric. The XRD result was quite consistent with the result showing the effect of phosphoric acid on the chemical composition, thermal shrinkage and weight reduction of rayon fabric.

Regulation of precursor solution concentration for In-Zn oxide thin film transistors

  • Chen, Yanping;He, Zhongyuan;Li, Yaogang;Zhang, Qinghong;Hou, Chengyi;Wang, Hongzhi
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1300-1305
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    • 2018
  • The tunable electronic performance of the solution-processed semiconductor metal oxide is of great significance for the printing electronics. In current work, transparent thin-film transistors (TFTs) with indium-zinc oxide (IZO) were fabricated as active layer by a simple eco-friendly aqueous route. The aqueous precursor solution is composed of water without any other organic additives and the IZO films are amorphous revealed by the X-ray diffraction (XRD). With systematic studies of atomic force microscopy (AFM), X-ray photoemission spectroscopy (XPS) and the semiconductor property characterizations, it was revealed that the electrical performance of the IZO TFTs is dependent on the concentration of precursor solution. As well, the optimum preparation process was obtained. The concentrations induced the regulation of the electronic performance was clearly demonstrated with a proposed mechanism. The results are expected to be beneficial for development of solution-processed metal oxide TFTs.