53 results on '"Haksoo Han"'
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2. Highly Transparent, Colorless Optical Film with Outstanding Mechanical Strength and Folding Reliability Using Mismatched Charge‐Transfer Complex Intensification (Adv. Funct. Mater. 20/2022)
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Chanjae Ahn, Tae Yong Kim, Pyong Hwa Hong, Sungwon Choi, Yea‐Jin Lee, Hanui Kwon, Hyeryeon Jeon, Dong Won Ko, In Park, Haksoo Han, and Sung Woo Hong
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Biomaterials ,Electrochemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
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Catalog
3. Highly Transparent, Colorless Optical Film with Outstanding Mechanical Strength and Folding Reliability Using Mismatched Charge‐Transfer Complex Intensification
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Chanjae Ahn, Tae Yong Kim, Pyong Hwa Hong, Sungwon Choi, Yea‐Jin Lee, Hanui Kwon, Hyeryeon Jeon, Dong Won Ko, In Park, Haksoo Han, and Sung Woo Hong
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Biomaterials ,Electrochemistry ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2022
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4. Structure Stability, Flame Retardancy, and Antimicrobial Properties of Polyurethane Composite Nanofibers Containing Tannic Acid and Boron‐Doped Carbon Nanotubes
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Young Nam Kim, Jun Young Jo, Yebom Kim, Yu‐Mi Ha, Haksoo Han, Doh C. Lee, Jaewoo Kim, and Yong Chae Jung
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Polymers and Plastics ,General Chemical Engineering ,Organic Chemistry ,Materials Chemistry - Published
- 2021
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5. Structure Stability, Flame Retardancy, and Antimicrobial Properties of Polyurethane Composite Nanofibers Containing Tannic Acid and Boron‐Doped Carbon Nanotubes
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Haksoo Han, Young Nam Kim, Doh C. Lee, Jun Young Jo, Yong Chae Jung, Yebom Kim, Yu-Mi Ha, and Jaewoo Kim
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Materials science ,Textile ,Polymers and Plastics ,business.industry ,General Chemical Engineering ,Organic Chemistry ,Antimicrobial ,chemistry.chemical_compound ,Boron doped carbon ,chemistry ,Chemical engineering ,Tannic acid ,Materials Chemistry ,Composite nanofibers ,business ,Polyurethane - Abstract
The development of tannic‐acid‐based textile materials is a good candidate that enables both flame retardancy and antibacterial properties. When nanocarbon materials are used together, it is possible to not only realize complex functions but also increase physical properties, thereby expanding the potential range of application of the materials. more...
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- 2021
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6. Thin and surface adhesive ferroelectric poly(vinylidene fluoride) films with β phase-inducing amino modified porous silica nanofillers
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Haksoo Han, Cheolmin Park, Kang Lib Kim, Ravindra V. Ghorpade, Giyoung Song, Vimal K. Tiwari, and Tae Hee Kim
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chemistry.chemical_classification ,Nanocomposite ,Materials science ,Polymers and Plastics ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Ferroelectricity ,0104 chemical sciences ,chemistry ,Spherulite ,Materials Chemistry ,Adhesive ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Thin film ,Composite material ,0210 nano-technology ,Fumed silica - Abstract
We report an efficient route for ferroelectric polar β phase generation in poly(vinylidene fluoride) (PVDF) through incorporation of amine functionalized, porous silica (MCM-41 and fumed silica) based nanofillers. These porous highly functionalized surfaces exhibit the efficient secondary interaction with polymer chain via hydrogen bonding. Structural analysis through FTIR, XRD, and TEM confirm high degree of ferroelectric polar β phase generation of PVDF through incorporation of amino modified porous silica nanofillers. Optimized loading (5 wt %) of amine functionalized, porous silica in PVDF matrix enhances relative intensity of β phase up to 75%. Disappearance of spherulite structure of PVDF with amino modified porous silica nanofillers, as confirmed through POM, TEM, SEM and AFM studies also supports the above conclusion. The P-E hysteresis loop at sweep voltage of ±50 V of a thin PVDF-amino modified porous nanofiller film shows excellent ferroelectric property with nearly saturated high remnant polarization 2.8 µC.cm−2 owing to its large proportion of β PVDF, whereas, a nonpolar pure PVDF thin film shows unsaturated hysteresis loop with 0.6 µC.cm−2 remnant polarization. PVDF films with the nanofillers exhibit strong adhesive strength over different metallic substrates making them have edge over PVDF in various thin film applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2401–2411 more...
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- 2016
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7. The Effects of Amide Groups on the Thermal and Optical Properties of Poly(amide-imide)s with Low Residual Stress for Microelectronic Devices
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Haksoo Han, Taewon Yoo, Jinyoung Kim, Hyemin Ha, Kwangin Kim, and Patrick Han
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Materials science ,Polymers and Plastics ,02 engineering and technology ,engineering.material ,010402 general chemistry ,01 natural sciences ,chemistry.chemical_compound ,Coating ,Residual stress ,Amide ,Polymer chemistry ,Materials Chemistry ,Microelectronics ,Physical and Theoretical Chemistry ,business.industry ,Organic Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,0104 chemical sciences ,Amorphous solid ,Chemical engineering ,chemistry ,Polyamide ,engineering ,0210 nano-technology ,business ,Glass transition ,Polyimide - Abstract
In this study, poly(amide-imide)s are synthesized for electronic materials by adding amide groups into polyimide. As it is expected, poly(amide-imide) shows an amorphous structure with a lower glass transition temperature and residual stress than the neat polyimide due to the high steric hindrance of the amide group. Also, the modification to the polyimide structure leads to higher transmittance and enhances colorless properties. Consequently, successful synthesis of poly(amide-imide)s is demonstrated which has wide applicability in the electronic industries due to their low glass transition temperature. It is expected that semiconductor and integrated circuit products can be manufactured utilizing poly(amide-imide)s with high reliability and a low chance of cracking due to their lower residual stress. Furthermore, it envisioned that the improved optical properties of poly(amide-imide) materials will allow for their applications in transparent displays and coating products. more...
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- 2016
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8. Flexible polymer thermoelectric device based on PEDOT:PSS and surface treated pyromellitic dianhydride‐oxydianiline polyimide substrate
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Hakgeun Jeong, Hyang-Hee Choi, Juheon Lee, Moonhyun Chung, Seo Hyun Kim, and Haksoo Han
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chemistry.chemical_classification ,Conductive polymer ,Pyromellitic dianhydride ,Materials science ,Polymers and Plastics ,General Chemistry ,Polymer ,Electrochemistry ,Polyimide substrate ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,PEDOT:PSS ,Thermoelectric effect ,Materials Chemistry - Published
- 2020
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9. Polybenzimidazole/inorganic composite membrane with advanced performance for high temperature polymer electrolyte membrane fuel cells
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Ki Ho Nam, Haksoo Han, Kwangwon Seo, and Jongchul Seo
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chemistry.chemical_classification ,Thermogravimetric analysis ,Materials science ,Polymers and Plastics ,02 engineering and technology ,General Chemistry ,Electrolyte ,Polymer ,Conductivity ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Membrane ,chemistry ,Phenylene ,Ultimate tensile strength ,Materials Chemistry ,Ceramics and Composites ,Composite material ,Fourier transform infrared spectroscopy ,0210 nano-technology - Abstract
In this work, Al–Si was synthesized via a sol–gel process and introduced in poly 2,2′-m-(phenylene)-5,5′-bibenzimidazole (PBI). As a result, a series of five Al–Si/PBI composite (ASPBI) membranes (0, 3, 6, 9, and 12 wt%) were developed and characterized for application in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). The chemical and morphological structure of ASPBI membranes were analyzed by Fourier transform infrared spectroscopy, X-ray diffractometer, and scanning electron microscopy. According to the doping level test and thermogravimetric analysis, as the concentration of Al–Si increased, the doping level increased up to 475% due to the affinity and interaction between Al and phosphoric acid (PA). Moreover, the proton conductivity, current density at 0.6 V, and maximum power density of ASPBI membranes increased up to 0.31 S cm−1, 0.320 A cm−2, and 0.370 W cm−2, respectively, because the increased concentration of Al–Si allows the membranes to hold more PA. Alternatively, as the amount of Al–Si increased, the tensile strength of PA-doped and -undoped membranes decreased. This was caused by both excess PA and aggregation, which can cause serious degradation of the membrane and induce cracks. Furthermore, the PA-doped and -undoped ASPBI12 had the lowest tensile strength of 11.6 and 77.2 MPa. The improved proton conductivity and single cell performance of ASPBI membranes implies that these membranes are possible candidates for HT-PEMFC applications. However, further studies seeking to enhance the compatibility between PBI and Al–Si and optimize the amount of filler should be performed. POLYM. COMPOS., 38:87–95, 2017. © 2015 Society of Plastics Engineers more...
- Published
- 2015
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10. Preparation and Characterization of Spherical Polyimide Aerogel Microparticles
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Haksoo Han, Jinuk Kwon, Jinyoung Kim, Taewon Yoo, and Dongmyung Park
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chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,business.industry ,General Chemical Engineering ,Catalyst support ,Thermal resistance ,Organic Chemistry ,Aerogel ,Polymer ,chemistry ,Thermal insulation ,Specific surface area ,Materials Chemistry ,Composite material ,business ,Porosity ,Polyimide - Abstract
In the study described here, novel, polyimide (PI)-based spherical aerogelmicroparticles are fabricated. The aerogel microparticles proposed in this study have an advantage over film-shaped aerogels because the microparticles can be easily used for thermal insulation, drug release, and catalyst support. By using only a PI polymer as the raw material for the proposed PI aerogel microparticles, the problems associated with reinforcing conventional silica aerogels, such as inferior thermal resistance or incorporation with silica aerogel, are circumvented. The porosity of PI aerogel microparticles was determined to be 80% and specific surface area was determined as 103 m2 g−1. The pore sizes measured using mercury intrusion porosimetry are between 4 and 100 nm, with a representative pore size of 15 nm. more...
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- 2014
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11. Water sorption and water-resistance properties of poly(vinyl alcohol)/clay nanocomposite films: Effects of chemical structure and morphology
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Sher Bahadar Khan, Mijin Lim, Haksoo Han, Dowan Kim, and Jongchul Seo
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Vinyl alcohol ,Nanocomposite ,Materials science ,Polymers and Plastics ,General Chemistry ,Fick's laws of diffusion ,Surface energy ,Contact angle ,chemistry.chemical_compound ,Crystallinity ,Montmorillonite ,chemistry ,Materials Chemistry ,Ceramics and Composites ,Composite material ,Dispersion (chemistry) - Abstract
A series of poly(vinyl alcohol)/sodium montmorillonite (PVA/NaMMT) nanocomposite films were prepared via a solution method, and their water sorption and water-resistant properties were investigated as a function of clay content. The water sorption and water resistance properties were strongly dependent on the chemical structure and film morphology originating from the NaMMT content. The water diffusion coefficient and water uptake of the PVA/NaMMT nanocomposite films were obtained by best fits to a Fickian diffusion model. The diffusion coefficient and water uptake in the PVA/NaMMT nanocomposite films varied between 8.16 × 10−10 and 3.60 × 10−10 cm2 s−1 and 35.6 and 29.9 wt%, respectively. Both the diffusion coefficient and water uptake decreased as the content of NaMMT in pure PVA was increased. Additionally, the water resistance pressure (mm) of the PVA/NaMMT nanocomposite films increased with increasing NaMMT content. Contact angle analyses showed that the chemical affinity to water and the surface energy of the nanocomposite films decreased with increasing NaMMT content. Furthermore, the well-dispersed and exfoliated structure in the nanocomposite films not only induced an increased tortuous path for water molecules to pass through, but also increased the molecular order. However, to enhance the water sorption properties and water resistance of hydrophilic PVA, further studies to increase the dispersion of clay particles and ensure desired morphological qualities such as crystallinity and molecular packing order in the PVA/clay nanocomposite films are required. POLYM. COMPOS., 36:660–667, 2015. © 2014 Society of Plastics Engineers more...
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- 2014
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12. Fabrication of polyimide composite films based on carbon black for high-temperature resistance
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JeeEun Lee, Haksoo Han, Jinuk Kwon, Dongmyung Park, Patrick Han, and Jinyoung Kim
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Fabrication ,Materials science ,Polymers and Plastics ,Composite number ,Thermal decomposition ,General Chemistry ,Carbon black ,Differential scanning calorimetry ,Thermal ,Materials Chemistry ,Ceramics and Composites ,Composite material ,Glass transition ,Polyimide - Abstract
A novel high-performance material, carbon black (CB) polyimide (PI), was obtained by the chemical synthesis of CB (carbon black N326) with PI. Following its synthesis, several analyses were carried out to investigate the thermal and mechanical properties of the newly synthesized CB-PI. The thermal decomposition temperature of CB-PI compared to PI increased by 76°C from 508 to 584°C. The glass transition temperature of CB-PI as evaluated by differential scanning calorimetry increased by 204°C from 379 to 583°C compared to that of PI. Moreover, the mechanical strength of CB-PI increased by 16% compared to that of PI. In addition, the analyses confirm that CB and PI in the synthesized CB-PI were chemically crosslinked, which was shown to be responsible for the superior thermal and mechanical properties of the CB-PI. POLYM. COMPOS., 35:2214–2220, 2014. © 2014 Society of Plastics Engineers more...
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- 2014
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13. The Preparation of Size-Controllable Hollow Polyimide Microspheres by Surface Imidization of Electrosprayed Droplets
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Hyun Min Jung, Byoung Gak Kim, Haksoo Han, Yu Min Park, Jong Chan Won, Yong Seok Kim, and Jin Young Park
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Electrospray ,Materials science ,Polymers and Plastics ,Precipitation (chemistry) ,General Chemical Engineering ,digestive, oral, and skin physiology ,Organic Chemistry ,Thin layer ,technology, industry, and agriculture ,Microsphere ,Volumetric flow rate ,Materials Chemistry ,Composite material ,Polyimide - Abstract
Hollow polyimide (PI) microspheres are prepared through an electrospraying process, followed by surface imidization. The precipitation of droplets at the interface between two immiscible liquids provides a scaffold for the formation of a thin layer while an in situ imidization reaction prevents the irreversible deformation of the hollow shell. This strategy easily yields robust hollow structures of PI microspheres. The electrospray process permitts the sizes of the hollow PI microspheres to be controlled through adjustments to the flow rate and concentration of the poly(amic acid) (PAA) solution. The electrospraying approach described here may be the most facile means yet reported for obtaining size-controlled hollow PI particles without the need for additives or surfactants. more...
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- 2013
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14. Preparation and characterization of poly(propylene carbonate)/exfoliated graphite nanocomposite films with improved thermal stability, mechanical properties and barrier properties
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Yunho Lee, Dowan Kim, Haksoo Han, Sher Bahadar Khan, and Jongchul Seo
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chemistry.chemical_classification ,Nanocomposite ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Composite number ,Thermal treatment ,Polymer ,chemistry.chemical_compound ,chemistry ,Propylene carbonate ,Materials Chemistry ,Thermal stability ,Graphite ,Composite material ,Dispersion (chemistry) - Abstract
Relatively high aspect ratio exfoliated graphite (EFG) particles with an average size of 7.4 mu m and a nanometer sized thickness of 30-50 nm were successfully prepared by thermal treatment at 1050 degrees C and subsequent ultrasonication for application as a filler to improve the physical properties of eco-friendly poly(propylene carbonate) (PPC). A series of poly(propylenecarbonate)/exfoliated graphite (PPC/EFG) nanocomposite films with different EFG contents were prepared via a solution blending method. The physical properties were strongly dependent upon the chemical and morphological structures originating from the differences in EFG composition. The morphological structures, thermal properties, mechanical properties and barrier properties of the nanocomposite films were investigated as a function of the EFG content. While all of the PPC/EFG nanocomposite films exhibited good dispersion of EFG to some extent, Fourier transform infrared and SEM results revealed that solution blending did not lead to strong interactions between PPC and EFG. As a result, poor dispersion occurred in composite films with a high EFG content. By loading EFG particles, the oxygen permeabilities, moisture permeabilities and water uptake at equilibrium decreased as the EFG content increased. Compared with pure PPC, PPC/EFG nanocomposite films have enhanced molecular ordering. Specifically, the 2% PPC/EFG composite film shows greater molecular ordering than the other composite films, which results in the highest mechanical strength. In future work, the compatibility and dispersion of the PPC matrix polymer and EFG filler particles should be increased by modifying the EFG surface or introducing additives more...
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- 2013
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15. Preparation and properties of poly(urethane acrylate) (PUA) and tetrapod ZnO whisker (TZnO-W) composite films
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Haksoo Han, Jongchul Seo, Dowan Kim, Yunho Lee, and Sher Bahadar Khan
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chemistry.chemical_classification ,Thermal oxidation ,Materials science ,Polymers and Plastics ,Organic Chemistry ,Composite number ,Polymer ,Oxygen transmission rate ,chemistry ,Whisker ,Materials Chemistry ,UV curing ,Thermal stability ,Composite material ,Fourier transform infrared spectroscopy - Abstract
Tetrapod zinc oxide whiskers (TZnO-Ws) were successfully synthesized via a thermal oxidation method and confirmed using Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. A series of poly(urethane acrylate) (PUA)/TZnO-W composite films with various TZnO-W contents were prepared via a UV curing method and their physical properties were investigated to understand their possible use as packaging materials. The morphological, thermal, mechanical, antibacterial and barrier properties of the PUA/TZnO-W composite films were interpreted as a function of TZnO-W content. The thermal stability, barrier properties and antibacterial properties of the composite films, which were strongly dependent upon their chemical and morphological structure, were enhanced as the TZnO-W content increased. The oxygen transmission rate and water vapor transmission rate decreased from 614 to 161 cm3 m−2 per day and 28.70 to 28.16 g m−2 per day, respectively. However, the mechanical strength of the films decreased due to the low interfacial interaction and poor dispersion with high TZnO-W loading. The enhanced barrier properties and good antibacterial properties of the PUA/TZnO-W composite films indicate that these materials are potentially suitable for many packaging applications. However, further studies are needed to increase the compatibility of polymer matrix and filler. © 2012 Society of Chemical Industry more...
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- 2012
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16. Preparation and properties of poly(propylene carbonate) and nanosized ZnO composite films for packaging applications
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Eui Soung Jang, Haksoo Han, Sher Bahadar Khan, Jongchul Seo, and Gwonyoung Jeon
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chemistry.chemical_classification ,Nanocomposite ,Materials science ,Polymers and Plastics ,Composite number ,Nanoparticle ,General Chemistry ,Polymer ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Oxygen permeability ,chemistry ,Propylene carbonate ,Materials Chemistry ,Polypropylene carbonate ,Composite material ,Dispersion (chemistry) - Abstract
A series of polypropylene carbonate (PPC)/ZnO nanocomposite films with different ZnO contents were prepared via a solution blending method. The morphological structures, thermal properties, oxygen permeability, water sorption, and antibacterial properties of the films were investigated as a function of ZnO concentration. While all of the composite films with less than 5 wt % ZnO exhibited good dispersion of ZnO in the PPC matrix, FTIR and SEM results revealed that solution blending did not lead to a strong interaction between PPC and unmodified ZnO. As such, poor dispersion was induced in the composite films with a high ZnO content. By incorporating inorganic ZnO filler nanoparticles, the diffusion coefficient, water uptake in equilibrium, and oxygen permeability decreased as the content of ZnO increased. The PPC/ZnO nanocomposite films also displayed a good inhibitory effect on the growth of bacteria in the antimicrobial analysis. The enhancement in the physical properties achieved by incorporating ZnO is advantageous in packaging applications, where antimicrobial and environmental-friendly properties, as well as good water and oxygen barrier characteristics are required. Furthermore, UV light below ∼ 350 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PPC matrix. ZnO nanoparticles can also improve the weatherability of a PPC film. In future research, the compatibility and dispersion of the PPC matrix polymer and the inorganic ZnO filler nanoparticles should be increased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011. more...
- Published
- 2011
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17. Nitrogen-Doped Porous Carbon Structure from Melamine-Assisted Polyimide Sheets for Supercapacitor Electrodes
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Dong Jun Kim, Haksoo Han, Gunhwi Kim, Seok Hee Lee, Jinyoung Kim, Daero Lee, and Jiwon Kim
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Supercapacitor ,Materials science ,Renewable Energy, Sustainability and the Environment ,Nitrogen doping ,Nitrogen doped ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Porous carbon ,chemistry ,Chemical engineering ,Electrode ,0210 nano-technology ,Melamine ,Polyimide ,General Environmental Science - Published
- 2018
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18. Residual stress and mechanical properties of polyimide thin films
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Sang Hyon Paek, Choonkeun Lee, Jongchul Seo, Wonbong Jang, and Haksoo Han
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Pyromellitic dianhydride ,Materials science ,Polymers and Plastics ,General Chemistry ,Nanoindentation ,BPDA ,Surfaces, Coatings and Films ,Stress (mechanics) ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Residual stress ,Materials Chemistry ,Composite material ,Thin film ,Polyimide - Abstract
Four different structure polyimide thin films based on 1,4-phenylene diamine (PDA) and 4,4′-oxydianiline (ODA) were synthesized by using two different dianhydrides, pyromellitic dianhydride (PMDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and their residual stress behavior and mechanical properties were investigated by using a thin film stress analyzer and nanoindentation method. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. The morphological structure of polyimide thin films was characterized by X-ray diffraction patterns and refractive indices. The residual stress was in the range of −5 to 38 MPa and increased in the following order: PMDA-PDA < BPDA-PDA < PMDA-ODA < BPDA-ODA. The hardness of the polyimide films increased in the following order: PMDA-ODA < BPDA-ODA < PMDA-PDA < BPDA-PDA. The PDA-based polyimide films showed relatively lower residual stress and higher hardness than the corresponding ODA-based polyimide films. The in-plane orientation and molecularly ordered phase were enhanced with the increasing order as follows: PMDA-ODA < BPDA-ODA < BPDA-PDA ∼ PMDA-PDA. The PDA-based polyimides, having a rigid structure, showed relatively better-developed morphological structure than the corresponding ODA-based polyimides. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 more...
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- 2009
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19. Thermal, optical, and water sorption properties in composite films of poly(ether imide) and bismaleimides: Effect of chemical structure
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Jongchul Seo, Wonbong Jang, and Haksoo Han
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chemistry.chemical_classification ,Materials science ,Thermoplastic ,Absorption of water ,Polymers and Plastics ,Chemical structure ,Composite number ,Ether ,General Chemistry ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Glass transition ,Imide - Abstract
Two series of semi-interpenetrating polymer network (semi-IPN) composite films, PEI/bismaleimide (UTBM) and PEI/fluorinated BMI (UTFBM) were prepared using a thermoplastic PEI and two different crosslinkable imide moieties. The effects of chemical structure and content of crosslinkable imide moieties on thermal stability, dielectric properties, and water sorption have been investigated. Glass transition temperature and weight loss temperatures increased with increase in the content of crosslinkable imide moieties, indicating the enhanced thermal stability of the semi-IPN composite films. The refractive indices of the semi-IPN composite systems increased with increasing crosslinkable imide moieties due to the higher polarizabilities of atoms. The water sorption of the semi-IPN composite films was significantly decreased by the incorporation of crosslinkable imide moieties, which are interpreted by morphological structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 more...
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- 2009
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20. A Novel Series of Heteropolynuclear Metallomesogens: Organopalladium Complexes with Ferrocenophane‐Containing Ligands
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Oleg N. Kadkin, Haksoo Han, Yuri G. Galyametdinov, and Jaein An
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chemistry.chemical_classification ,Ketone ,Chemistry ,chemistry.chemical_element ,Thermotropic crystal ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,Ultraviolet visible spectroscopy ,Ferrocene ,Liquid crystal ,Organopalladium ,Proton NMR ,Palladium - Abstract
Ferrocenophane-containing (Fcph) Schiff's bases p-C 12 H 25 O-(C 6 H 4 )CH=N(C 6 H 4 )Fcph (L A H) and p-C 12 H 25 O(C 6 H 4 )COO-(C 6 H 4 )CH=N(C 6 H 4 )Fcph (L B H) react with palladium(II) acetate to form μ-acetato- and chloro-bridged dimeric organopalladium complexes. By exchanging acetato-groups with the chloride anions, μ-chloro-bridged heteropolynuclear dimers are obtained that show thermotropic smectic A phases over a temperature range of 198 to 260 °C. The complexes [PdCIL A ] 2 and [PdCΙL B ] 2 can be transformed into a variety of mixed-ligand Pd ΙΙ complexes by treatment with salicyl-aldimine p-C 12 H 25 O(C 6 H 4 )COO(C6H3)(OH)CH=N(C6H4)-Fcph (L C H) and β-aminovinyl ketone p-C 12 H 25 O(C 6 H 4 )-COCH=CHNH(C 6 H 4 )Fcph (L D H). The obtained mixed-ligand heterometallic complexes [PdL A L C ], [PdL B L C ], [PdL A L D ] and [PdL B L D ] exhibit enantiotropic, thermotropic nematic phases over a broad temperature range from 71 to 205 °C. The structures of the synthesized compounds were characterized by means of 1 H NMR, IR and UV spectroscopy, as well as elemental analysis. The liquid crystalline properties were studied by polarising optical microscopy and DSC. more...
- Published
- 2008
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21. Novel poly(methyl methacrylate)-block-polyurethane-block-poly(methyl methacrylate) tri-block copolymers through atom transfer radical polymerization
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Seok Kyu Lee, Haksoo Han, Wonbong Jang, Sanghyun Baek, Jongchul Seo, Hemant K. Verma, and K. Tharanikkarasu
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Materials science ,Telechelic polymer ,Polymers and Plastics ,Atom-transfer radical-polymerization ,General Chemistry ,Poly(methyl methacrylate) ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Polymerization ,chemistry ,Catalytic chain transfer ,visual_art ,Polymer chemistry ,Materials Chemistry ,visual_art.visual_art_medium ,Copolymer ,Living polymerization ,Methyl methacrylate - Abstract
Poly(methyl methacrylate)-block-polyurethane-block-poly(methyl methacrylate) tri-block copolymers have been synthesized successfully through atom transfer radical polymerization of methyl methacrylate using telechelic bromo-terminated polyurethane/CuBr/N,N,N,N″,N″-pentamethyldiethylenetriamine initiating system. As the time increases, the number-average molecular weight increases linearly from 6400 to 37,000. This shows that the poly methyl methacrylate blocks were attached to polyurethane block. As the polymerization time increases, both conversion and molecular weight increased and the molecular weight increases linearly with increasing conversion. These results indicate that the formation of the tri-block copolymers was through atom transfer radical polymerization mechanism. Proton nuclear magnetic resonance spectral results of the triblock copolymers show that the molar ratio between polyurethane and poly (methyl methacrylate) blocks is in the range of 1 : 16.3 to 1 : 449.4. Differential scanning calorimetry results show Tg of the soft segment at −35°C and Tg of the hard segment at 75°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 more...
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- 2008
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22. Correlation of residual stress and adhesion on copper by the effect of chemical structure of polyimides for copper-clad laminates
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Minbum Seo, Sunggook Park, Jongchul Seo, Haksoo Han, and Wonbong Jang
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Copper oxide ,Materials science ,Polymers and Plastics ,Organic Chemistry ,chemistry.chemical_element ,Adhesion ,Copper ,Stress (mechanics) ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Residual stress ,Materials Chemistry ,Composite material ,Thin film ,Polyimide - Abstract
BACKROUND: Polyimide films coated on copper are a potential new substrate for fabricating printed circuit boards; however, adhesion between the copper and polyimide films is often poor. The relations between residual stress and adhesion strength according to the development of molecular orientation of polyimide films with different chemical backbone structure coated on copper were studied. RESULTS: The effect of chemical structures on properties including the residual stress and the adhesion strength were widely investigated for four different polyimides. Diamine 4,4′-oxydianiline (ODA) and dianhydrides 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′-oxydiphthalic anhydride (ODPA) and 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) were used to synthesize polyimide. In an attempt to quantify the interaction of thermal mismatch with the polyimide films depending on various structures, residual stress experiments between polyimide film and CuSi wafer were carried out over a range of 25–400 °C using in situ thin film stress analysis. A universal test machine was used to conduct 180° peel test (ASTM D903-98) of polyimide film from cooper foil. The residual stress on CuSi (100) wafer decreased in the order 6FDA-ODA > BTDA-ODA > ODPA-ODA > PMDA-ODA, and the interfacial adhesion strength decreased in the order BTDA-ODA (5 N mm−2) > ODPA-ODA > PMDA-ODA > 6FDA-ODA. The results may suggest that the morphological structure, degree of crystallinity of chain orientation and packing significantly relate to the residual stress and adhesion strength in polyimide films. Wide-angle X-ray diffraction was used for characterizing the molecular order and orientation and X-ray photoelectron spectroscopy was used for the analysis of components on copper after polyimide films were detached to confirm the existence of copper oxide chemical bonding and to measure the binding energy of elements on the copper surface. CONCLUSION: In this research, it is demonstrated that BTDA-ODA polyimide has a low residual stress to copper, good adhesion property, good thermal property and low dielectric constant. Therefore, BTDA-ODA would be expected to be a promising candidate for a two-layer copper-clad laminate. Copyright © 2007 Society of Chemical Industry more...
- Published
- 2007
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23. Sulfonated polyimide and poly (ethylene glycol) diacrylate based semi-interpenetrating polymer network membranes for fuel cells
- Author
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Seokkyu Lee, Wonbong Jang, Yong Gun Shul, Haksoo Han, Seung-Hyuk Choi, and K. Tharanikkarasu
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Condensation polymer ,Materials science ,Polymers and Plastics ,General Chemistry ,Polyelectrolyte ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Membrane ,chemistry ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Interpenetrating polymer network ,Prepolymer ,Ethylene glycol ,Polyimide - Abstract
Semi-interpenetrating polymer network (semi-IPN) membranes based on novel sulfonated polyimide (SPI) and poly (ethylene glycol) diacrylate (PEGDA) have been prepared for the fuel cell applications. SPI was synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminobiphenyl 2,2′-disulfonic acid, and 2-bis [4-(4-aminophenoxy) phenyl] hexafluoropropane. PEGDA was polymerized in the presence of SPI to synthesize semi-IPN membranes of different ionic contents. These membranes were characterized by determining, ion exchange capacity, water uptake, water stability, proton conductivity, and thermal stability. The proton conductivity of the membranes increased with increasing PEGDA content in the order of 10−1 S cm−1 at 90°C. These interpenetrating network membranes showed higher water stability than the pure acid polyimide membrane. This study shows that semi-IPN SPI membranes based on PEGDA which gives hydrophilic group and structural stability can be available candidates comparable to Nafion® 117 over 70°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 more...
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- 2007
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24. The effect of the ring opening polymerization and chain spacing on the coefficient of thermal expansion and modulus of polyimide
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Haksoo Han, Kwangin Kim, Wonbong Jang, and Taewon Yoo
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Materials science ,Polymers and Plastics ,General Chemistry ,Dynamic mechanical analysis ,Ring-opening polymerization ,Thermal expansion ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Dynamic modulus ,Materials Chemistry ,Thermomechanical analysis ,Thermal stability ,Composite material ,Polyimide ,Norbornene - Abstract
The features of norbornene (NE) cross-linked polyimide (PI) were investigated as the ratio of the norbornene monomer was varied. The coefficient of thermal expansion and modulus are important parameters of materials used in the microelectronic industry. Therefore, in this study, 5-norbornene-2, 3-dicarboxylic acid (NE) was introduced as a crosslinking agent to increase the thermal stability at elevated temperatures. 4,4′-Benzophenonetetracarboxylic dianhydride was utilized as a dianhydride and 4,4′-diaminodiphenyl ether was introduced as a diamine monomer. By changing the ratio of each monomer, we were able to control the spacing of the chain and ring opening polymerization, which resulted in improved properties. Each sample was thermally cured which led to a ring opening mechanism of the norbornene through the reverse Diels-Alder reaction. Thermal mechanical analysis was utilized to determine the coefficient of thermal expansion and dynamic mechanical analysis was used to determine the storage modulus (e′) and loss modulus (e″) of the PI film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42607. more...
- Published
- 2015
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25. Synthesis and characterization of sulfonated polyimides containing aliphatic linkages in the main chain
- Author
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Seung-Hyuk Choi, Wonbong Jang, Haksoo Han, Yong Gun Shul, and Dowan Kim
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Polymers and Plastics ,Organic Chemistry ,Conductivity ,Polyelectrolyte ,Hydrolysis ,chemistry.chemical_compound ,Membrane ,chemistry ,Diamine ,Nafion ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Polyimide - Abstract
A series of six-membered sulfonated polyimides with aliphatic linkages (SPIAs) was successfully synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminobiphenyl 2,2′-disulfonic acid (BDSA) as the sulfonated diamine, and aliphatic diamines H2N(CH2)nNH2 where n = 6, 8, 10, 12. These SPIAs were evaluated for thermal stability, ion exchange capacity (IEC), water uptake, proton conductivity, and hydrolytic stability. Proton conductivity and hydrolytic stability of the SPIAs were compared with the fully aromatic polyimide (MDA-SPI) prepared from 4,4′-methylenedianiline (MDA), BDSA, and NTDA. All the SPIAs exhibited high thermal stability. As the chain length of the aliphatic diamine decreased, the IEC and water uptake of the SPIAs increased. The SPIAs showed higher proton conductivity than commercially available membranes such as Nafion 117 at high temperatures and higher proton conductivity than MDA-SPI at all temperatures. All SPIAs exhibited a hydrolytic stability more than twice as high as that of MDA-SPI. Copyright © 2006 Society of Chemical Industry more...
- Published
- 2006
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26. Synthesis and characterization of new functional poly(urethane-imide) crosslinked networks
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Yong Gun Shul, Wonbong Jang, Haksoo Han, Mi Hee Park, and Seung Jin Yang
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Materials science ,Polymers and Plastics ,General Chemistry ,Dynamic mechanical analysis ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Polycaprolactone ,Materials Chemistry ,Ethyl acrylate ,Thermal stability ,Composite material ,Glass transition ,Maleimide ,Polyimide ,Polyurethane - Abstract
To synthesize new functional poly(urethane-imide) crosslinked networks, soluble polyimide from 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 4,4′-oxydianiline, and maleic anhydride and polyurethane prepolymer from polycaprolactone diol, tolylene 2,4-diisocyanate and hydroxyl ethyl acrylate were prepared. Poly(urethane-imide) thin films were finally prepared by the reaction between maleimide end-capped soluble polyimide (PI) and acrylate end-capped polyurethane (PU). The effect of polyurethane content on dielectric constant, residual stress, morphology, thermal property, and mechanical property was studied by FTIR, prism coupler, Thin Film Stress Analyzer (TFSA), XRD, TGA, DMTA, and Nano-indentation. Dielectric constant of poly(urethane-imide) thin films (2.39–2.45) was lower than that of pure polyimide (2.46). Especially, poly(urethane-imide) thin films with 50% of PU showed lower dielectric constant than other poly(urethane-imide) thin films did. Lower residual stress and slope in cooling curve were achieved in higher PU content. Compared to typical polyurethane, poly(urethane-imide) thin films exhibited better thermal stability due to the presence of the imide groups. The glass transition temperature, modulus, and hardness decreased with increase in the flexible PU content even though elongation and thermal expansion coefficient increased. Finally, poly(urethane-imide) thin films with low residual stress and dielectric constant, which are strongly affected by the morphological structure, chain mobility, and modulus, can be suggested to apply for electronic devices by variation of PU. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 113–123, 2006 more...
- Published
- 2006
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27. Water sorption and diffusion behaviors in composite films of poly(ether imide) and bismaleimide
- Author
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Jongchul Seo, Wonbong Jang, Choonkeun Lee, Haksoo Han, and Saimani Sundar
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Absorption of water ,Materials science ,Polymers and Plastics ,Diffusion ,Intermolecular force ,Composite number ,Ether ,General Chemistry ,Activation energy ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Composite material ,Imide ,Polyimide - Abstract
The effect of a crosslinkable imide moiety, bismaleimide (BMI), on the water sorption properties of poly(ether imide) (PEl) was gravimetrically measured and interpreted together with the chemical and morphological structures in composite films. The morphological structure of composite films was investigated by using a prism coupler and X-ray diffraction pattern. It indicated that the in-plane orientation and intermolecular packing order increased as the content of BMI in composite films increased. The water sorption behaviors showed dependence on the morphological change originating from the addition of BMI to PEI. The composite film with relatively high content of BMI exhibited a relatively high degree of in-plane orientation and a small mean intermolecular distance, which resulted in a decrease in the diffusion rate and water sorption and an increase in the activation energy in composite films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1692–1697, 2006 more...
- Published
- 2005
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28. Crosslinked sulfonated polyimide networks as polymer electrolyte membranes in fuel cells
- Author
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Wonbong Jang, Saimani Sundar, Choonkeun Lee, Yong Gun Shul, and Haksoo Han
- Subjects
chemistry.chemical_classification ,Conductive polymer ,Materials science ,Polymers and Plastics ,Decane ,Polymer ,Condensed Matter Physics ,Hexane ,chemistry.chemical_compound ,Membrane ,chemistry ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Physical and Theoretical Chemistry ,Polyimide ,Alkyl - Abstract
Sulfonated polyimides with tertiary nitrogen in the polymer backbone were synthesized with 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-diaminobiphenyl 2,2'-disulfonic acid, 2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, and diaminoacrydine hemisulfate. They were crosslinked with a series of dibromo alkanes to improve the hydrolytic stability. The crosslinked sulfonated polyimide films were characterized for their thermal stability, ion-exchange capacity (IEC), water uptake, hydrolytic stability, and proton conductivity. All the sulfonated polyimides had good thermal stability and exhibited a three-step degradation pattern. With an increase in the alkyl chain length of the crosslinker, IEC decreased as 1.23 > 1.16 > 1.06 > 1.01, and the water uptake decreased as 7.29 > 6.70 > 6.55 > 5.63. The order of the proton conductivity of the crosslinked sulfonated polyimides at 90 C was as follows: polyimide crosslinked with dibromo butane (0.070) > polyimide crosslinked with dibromo hexane (0.055) > polyimide crosslinked with dibromo decane (0.054). The crosslinked polyimides showed higher hydrolytic stability than the uncrosslinked polyimides. Between the crosslinked polyimides, the hydrolytic stability decreased with an increase in the alkyl chain length of the crosslinker. The crosslinked and uncrosslinked sulfonated polyimides exhibited almost the same proton conductivities. more...
- Published
- 2005
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29. The effect of crosslinked networks with poly(ethylene glycol) on sulfonated polyimide for polymer electrolyte membrane fuel cell
- Author
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Choonkeun Lee, Haksoo Han, Seung Jin Yang, Wonbong Jang, and Yong Gun Shul
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chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,technology, industry, and agriculture ,Chemical modification ,Maleic anhydride ,macromolecular substances ,Polymer ,Condensed Matter Physics ,chemistry.chemical_compound ,Membrane ,chemistry ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Physical and Theoretical Chemistry ,Fourier transform infrared spectroscopy ,Ethylene glycol ,Polyimide - Abstract
To investigate the effect of crosslinking by a hydrophilic group on a sulfonated polyimide electrolyte membrane, sulfonated polyimide end-capped with maleic anhydride was synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminobiphenyl, 2,2′-disulfonic acid, 2-bis [4-(4-aminophenoxy)phenyl] hexafluropropane and maleic anhydride. The sulfonated polyimides end-capped with maleic anhydride were self-crosslinked or crosslinked with poly(ethylene glycol) diacrylate. A series of the crosslinked sulfonated polyimides having various ratios of sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and compared with uncrosslinked and self-crosslinked sulfonated polyimides. The synthesized sulfonated polyimide films were characterized for FTIR spectrum, thermal stability, ion exchange capacity, water uptake, hydrolytic stability, morphological structure, and proton conductivity. The formation of sulfonated polyimide was confirmed in FTIR spectrum. Thermal stability was good for all the sulfonated polyimides that exhibited a three-step degradation pattern. Ion exchange capacity was the same for both the uncrosslinked and the self-crosslinked sulfonated polyimides (1.30 mEq/g). When the crosslinked sulfonated polyimides with poly(ethylene glycol) were compared, the ion exchange capacity was decreased as 1.27 > 1.25 > 1.23 mEq/g and water uptake was increased as 23.8 < 24.0 < 24.3% with the increase in poly(ethylene glycol) diacrylate content. All the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate were stable for over 200 h at 80 °C in deionized water. Morphological structure and mean intermolecular distance were obtained by WAXD. Proton conductivities were measured at 30, 50, 70, and 90 °C. The proton conductivity of the crosslinked sulfonated polyimides with poly(ethylene glycol) diacrylate increased with the increase in poly(ethylene glycol) diacrylate content despite the fact that the ion exchange capacity was decreased. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1455–1464, 2005 more...
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- 2005
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30. Nanoindentation studies of polyimide thin films with various internal linkages in the diamine component
- Author
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Jinuk Kwon, Byoungryul Min, Choonkeun Lee, Sunggook Park, Haksoo Han, and Saimani Sundar
- Subjects
Materials science ,Polymers and Plastics ,Nanoindentation ,Condensed Matter Physics ,BPDA ,chemistry.chemical_compound ,Crystallinity ,Prism coupler ,chemistry ,Indentation ,Diamine ,Materials Chemistry ,Physical and Theoretical Chemistry ,Thin film ,Composite material ,Polyimide - Abstract
Polyimide thin films were synthesized from 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) and four different diamines (p-phenylene diamine, 4,4′-oxydiphenylene diamine, 4,4′-biphenylene diamine, and 4,4′-sulfonyldiphenylene diamine). The nanoindentation behavior of the resulting polyimides, namely, poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA), poly(4,4′-biphenylene biphenyltetracarboximide) (BPDA-BZ), poly(4,4′-oxydiphenylene biphenyltetracarboximide) (BPDA-ODA), and poly(4,4′-sulfonyldiphenylene biphenyltetracarboximide) (BPDA-DDS), were investigated. Also, the morphological properties were characterized with a prism coupler and wide-angle X-ray diffraction and were correlated to the nanoindentation studies. The nanoindentation behavior and hardness varied quite significantly, depending on the changes in the chemical and morphological structures. The hardness of the polyimide thin films increased in the following order: BPDA-DDS < BPDA-ODA < BPDA-BZ < BPDA-PDA. For all the polyimide thin films, except that of BPDA-BZ, the hardness decreased with an increase in the load. The birefringence, a measure of the molecular in-plane orientation, increased in the following order: BPDA-DDS < BPDA-ODA < BPDA-PDA < BPDA-BZ. The X-ray diffraction studies revealed that the crystallinity of the polyimide thin films varied with the changes in the chemical structure. The studies showed that the indentation response with an applied load and the hardness by nanoindentation for the BPDA-based polyimides were closely related to the morphological structure. The nanoindentation and birefringence results revealed that the mechanical properties of the polyimide thin films were dependent on the crystallinity, which arose because of the chain order along the chain axis and the molecular packing order. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 861–870, 2004 more...
- Published
- 2004
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31. Structure-property correlations of sulfonated polyimides. I. Effect of bridging groups on membrane properties
- Author
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Jinuk Kwon, Haksoo Han, Saimani Sundar, and Choonkeun Lee
- Subjects
chemistry.chemical_classification ,Polymers and Plastics ,Organic Chemistry ,Conductivity ,Sulfonic acid ,chemistry.chemical_compound ,Membrane ,chemistry ,Diamine ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Solubility ,Perylenetetracarboxylic dianhydride ,Alkyl - Abstract
A series of sulfonated polyimides with increasing alkyl substituents in the o-position to diamine were synthesized from 4,4′-methylene dianiline, 4,4′-diamine-3,3′-dimethyl-diphenylmethane, and 4,4′-diamine-3,5,3′,5′-tetraethyl-diphenylmethane using 1,4,5,8-naphthalenetetracarboxylic dianhydride and perylenetetracarboxylic dianhydride by chemical imidization method. 4,4′-Diaminobiphenyl 2,2′-disulfonic acid was used as sulfonated diamine. The variation in the membrane properties with increase in substitution was analyzed. Solubility increased with substitution whereas the thermal stability decreased with increase in substitution. Ion exchange capacity and water uptake reduced with increase in substitution because of the low sulfonic acid content at a particular weight due to the increased molecular weight of the repeating unit. The conductivity of the substituted diamines was higher than the unsubstituted diamines at higher temperature regardless of low ion exchange capacity and water uptake. The increase in conductivity with increase in temperature was more rapid in polyimides than in Nafion®115. Hydrolytic stability of the polyimides with substitution is more than the unsubstituted diamines. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3621–3630, 2004 more...
- Published
- 2004
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32. Synthesis and characterization of poly(epoxy-imide) crosslinked networks
- Author
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Haksoo Han, Wonbong Jang, Saimani Sundar, Jinuk Kwon, Seung Jin Yang, and Choonkeun Lee
- Subjects
Materials science ,Polymers and Plastics ,Dielectric ,Epoxy ,Condensed Matter Physics ,Stress (mechanics) ,chemistry.chemical_compound ,chemistry ,Residual stress ,visual_art ,Materials Chemistry ,visual_art.visual_art_medium ,Thermal stability ,Physical and Theoretical Chemistry ,Thin film ,Composite material ,Imide ,Cooling curve - Abstract
Poly(epoxy imide)s were prepared by a reaction between a hydroxyl-group-containing soluble copolyimide and commercial epoxy resins at 220 °C for 2 h. Poly(epoxy imide) thin films exhibited higher thermal stability and lower dielectric constants than a commercial flip-chip package material (U300). The thermal stabilities of the poly(epoxy imide)s were 1.4-2.0 times higher than that of U300. The thermal stability increased with increasing crosslink density and with decreasing bulky CF 3 groups (which were easily decomposable). The dielectric constants of the poly(epoxy imide)s were 1.1-1.3 times lower than that of U300, and this is highly desirable for the microelectronic packaging industry. The dielectric constant dramatically decreased when bulky CF 3 groups were added and when the functionalities of epoxy resins decreased. The residual stresses, slopes in the cooling curves, and glass-transition temperatures of the poly(epoxy imide)s were measured with a thin-film stress analyzer. Low residual stresses and slopes in the cooling curves were achieved with a higher crosslink density. However, in the presence of bulky CF 3 groups, the copolyimide backbone structure did not affect the residual stress values. more...
- Published
- 2004
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33. Synthesis and characterization of soluble polyimides containing trifluoromethyl groups in their backbone
- Author
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Wonbong Jang, Saimani Sundar, Seung Jin Yang, Sang U.K. Kim, Choonkeun Lee, and Haksoo Han
- Subjects
chemistry.chemical_classification ,Materials science ,Trifluoromethyl ,Polymers and Plastics ,Dielectric ,Polymer ,Condensed Matter Physics ,Amorphous solid ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,Diamine ,Polymer chemistry ,Materials Chemistry ,Thermal stability ,Physical and Theoretical Chemistry ,Solubility - Abstract
A series of polyimides were synthesized from 2,2-Bis(3,4-dicarboxyphenyl)hexafluoropropane, 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, and 4,4′-oxydianiline by chemical imidization. The effects of the diamine ratios on the properties of the films were evaluated through the study of their thermal, electrical, and morphological properties. All the polymers exhibited better solubility in most of the organic solvents and hence were easily processable. Polyimides with more 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane exhibited better solubility and a low refractive index, which is highly desired for microelectronic applications. The dielectric constant and birefringence were strongly dependent on the fluorine content. With an increase in the fluorine substitution, both the dielectric constant and birefringence decreased. All the polymers exhibited high thermal stability (>400 °C). The absence of crystalline melting in differential scanning calorimetry and broad wide-angle X-ray diffraction patterns revealed the amorphous nature of the polymers, which was due to the presence of bulky CF3 groups and hinged ether linkages of the diamine component. The residual stress values decreased with an increase in the 4,4′-oxydianiline content, and the results were in agreement with the dielectric constant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4303–4312, 2004 more...
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- 2004
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34. Structure-property correlations of sulfonated polyimides. II. Effect of substituent groups on membrane properties
- Author
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Choonkeun Lee, Saimani Sundar, Jinuk Kwon, and Haksoo Han
- Subjects
Polymers and Plastics ,Organic Chemistry ,Materials Chemistry - Published
- 2004
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35. Nanoindentation and optical properties of poly(4,4?-oxydiphenylenep-phenylene pyromellitimide) copolyimide thin films according to thep-phenylene diamine content
- Author
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Choonkeun Lee, N. Padmanabha Iyer, and Haksoo Han
- Subjects
Birefringence ,Materials science ,Polymers and Plastics ,Modulus ,Nanoindentation ,Condensed Matter Physics ,Prism coupler ,Phenylene ,Materials Chemistry ,Physical and Theoretical Chemistry ,Thin film ,Composite material ,Refractive index ,Polyimide - Abstract
Poly(p-phenylene pyromellitimide) (PMDA-PDA), poly(oxydiphenylene pyromellitimide) (PMDA-ODA), and poly(4,4'-oxydiphenylene p-phenylene pyromellitimide) random copolyimide thin films with different p-phenylene diamine (PDA) contents were prepared. Nanoindentation was used to characterize the mechanical properties (hardness and modulus), and a prism coupler was used for measuring the optical properties (refractive index and birefringence). The hardness and modulus were calculated from curves of the nanoindentation load versus the displacement. The effect of the PDA content on the hardness and modulus was studied. The hardness of the polyimide thin films varied from 0.248 to 0.613 GPa, and the modulus varied from 3.78 to 6.75 GPa at a load of 0.127 mN. The hardness and modulus increased with increasing PDA content, whereas the penetration depth and plastic deformation decreased. As the load increased, the penetration depth increased. The hardness of PMDA-ODA films remained constant, whereas that of PMDA-PDA and PMDA-ODA/PDA films decreased with increasing load. The in-plane refractive index varied from 1.7219 to 1.8244, and the out-of-plane refractive index varied from 1.6390 to 1.5827, as a function of the PDA content. The birefringence varied with the PDA content from 0.0829 to 0.2417. The morphological structure of the prepared polyimide thin films was investigated with wide-angle X-ray diffraction. The mechanical properties and optical properties of the polyimide thin films were strongly dependent on the changes in the morphological structure, which originated from the variation of the composition. more...
- Published
- 2004
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36. Effect of hydrophobic hexafluoroisopropylidene group on the water sorption behaviors of rigid poly(p-phenylene pyromellitimide) polyimide thin films
- Author
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Jongchul Seo, Sang Yup Lee, Haksoo Han, and Wonbong Jang
- Subjects
Absorption of water ,Materials science ,Polymers and Plastics ,Intermolecular force ,General Chemistry ,Activation energy ,Fick's laws of diffusion ,Surfaces, Coatings and Films ,Crystallinity ,Chemical engineering ,Poly(p-phenylene) ,Polymer chemistry ,Materials Chemistry ,Thin film ,Polyimide - Abstract
We prepared poly(p-phenylene pyromellitimide) (PMDA–PDA), poly(p-phenylene 4,4′-hexafluoroisopropylidene diphthalimide), and their copolyimides with various compositions to explore the relationship between the water sorption and structure. The water sorption behaviors were gravimetrically investigated as a function of composition and temperature and interpreted with a Fickian diffusion model in films. Overall, the water sorption behaviors were strongly dependent on the changes in morphological structure, which originated from the variations in composition. When the content of the bulky hexafluoroisopropylidene group (6FDA) was increased, the water uptake decreased from 5.80 to 3.18 wt %, whereas the diffusion coefficient increased from 3.6 × 10−10 to 11.3 × 10−10 cm2/s. The relatively high water uptake in the PMDA–PDA polyimide film was successfully healed by the incorporation of 6FDA, which may have resulted from the increases in the intermolecular packing order and hydrophobicity. The degree of orientation and crystallinity, which are in-plane characteristics, were directly correlated to the diffusion coefficient and activation energy in the polyimide film. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3442–3446, 2003 more...
- Published
- 2003
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37. Synthesis and characterization of novel poly(amide-imide)s containing 1,3-diamino mesitylene moieties
- Author
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Heyungsuk Pak, Choonkeun Lee, Haksoo Han, N. Padmanabha Iyer, and Kyungwook Min
- Subjects
Thermogravimetric analysis ,Trifluoromethyl ,Polymers and Plastics ,Organic Chemistry ,chemistry.chemical_compound ,chemistry ,Diamine ,Polyamide ,Polymer chemistry ,Pyridine ,Materials Chemistry ,Thermal stability ,Imide ,Mesitylene - Abstract
A series of poly(amide-imide)s were prepared using a new monomer, 1,3-bis(trimellitimido)-2,4,6-trimethyl benzene (BTB), with four different diamines: 1,4-phenylene diamine (PDA), 2,4-diamino mesitylene (DAM), 2,2'-dimethyl-4,4'-diamino biphenyl (DMDB), and 2,2'-bis(trifluoromethyl)-4,4'-diamino biphenyl (TFDB). They were prepared by the condensation method in N-methyl-2-pyrrolidinone (NMP) solvent using triphenyl phosphate and pyridine as condensing agents. The synthesized poly(amide-imide) were characterized by Fourier transform infrared and 1 H NMR techniques. Films were prepared and characterized using DSC, thermogravimetric analysis (TGA), a prism coupler, and a film dielectric property analyzer. DSC measurement showed that the glass-transition temperatures of the polymers were in the range of 259-327 °C. TGA analysis showed 5% weight loss, in the range of 472-514 °C. The refractive index varied from 1.6004 to 1.6586 in the following increasing order: BTB-TFBM < BTB-DAM < BTB-DMDB < BTB-PDA. For the poly(amide-imide) films, the birefringence varied in the range of 0.0319-0.0580, in the following increasing order: BTB-DAM < BTB-TFBM < BTB-DMDB < BTB-PDA. The capacitance method showed that the dielectric constant of poly(amide-imide) varied with the diamine structure; no difference was found by the optical method. more...
- Published
- 2003
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38. Dielectric properties of oxydianiline-based polyimide thin films according to the water uptake
- Author
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Yong Gun Shul, Choonkeun Lee, and Haksoo Han
- Subjects
Materials science ,Absorption of water ,Polymers and Plastics ,Diffusion ,Analytical chemistry ,Dielectric ,Condensed Matter Physics ,BPDA ,Capacitance ,chemistry.chemical_compound ,chemistry ,Chemical affinity ,Polymer chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Thin film ,Polyimide - Abstract
For polyimide thin films, the dielectric properties were investigated with the capacitance and optical methods. The dielectric constants of the 4,4'-oxydianiline (ODA)-based polyimide thin films varied from 2.49 to 3.10 and were in the following decreasing order: 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA)-ODA > 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA)-ODA > 4,4'-hexafluoroisopropylidene diphthalic dianhydride (6FDA)-ODA. According to the absorption of water, the diffusion coefficients in the films varied from 4.8 x 10 -10 to 7.2 x 10 -10 cm 2 /s and were in the following increasing order: BPDA-ODA < PMDA-ODA < 6FDA-ODA. The dielectric constants and diffusion coefficients of the polyimides were affected by the morphological structures, including the molecular packing order. However, because of the water uptake, the changes in the dielectric constants in the polyimide thin films varied from 0.49 to 1.01 and were in the following increasing order: BPDA-ODA < 6FDA-ODA < PMDA-ODA. Surprisingly, 6FDA-ODA with bulky hexafluoroisopropylidene groups showed less of a change in its dielectric constant than PMDA-ODA. The total water uptake for the polyimide thin films varied from 1.43 to 3.19 wt % and was in the following increasing order: BPDA-ODA < 6FDA-ODA < PMDA-ODA. This means that the changes in the dielectric constants in the polyimide thin films were significantly related to the morphological structure and hydrophobicity of hexafluoroisopropylidene groups. Therefore, the morphological structure and chemical affinity in the polyimide thin films were important factors in controlling the dielectric properties. more...
- Published
- 2002
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39. Reduction of dielectric constant by nanovoids formed through chemical treatment on silica crosslinked polyimide and its effect on properties
- Author
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Sang-Youp Lee, Ravindra V. Ghorpade, Juheon Lee, Haksoo Han, Taewon Yoo, Jungkun Song, Seungsu Baek, and Kwangin Kim
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Materials science ,Polymers and Plastics ,02 engineering and technology ,General Chemistry ,Dielectric ,Dynamic mechanical analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Monomer ,Hydrofluoric acid ,chemistry ,Covalent bond ,Materials Chemistry ,Copolymer ,Thermal stability ,Composite material ,0210 nano-technology ,Polyimide - Abstract
In this study, 2,7-diamino-9-fluorenol (DAF) has been introduced to bond silica to the main chain of the polyimide (PI) copolymer. DAF contains a hydroxyl group that could covalently bond with silica particles. 4,4′-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4′-oxydianiline (4,4′-ODA) have been used as monomers to form a copolymer with DAF. The variation of silica content was controlled as 5%, 7.5, 10, 12.5 wt %. Variation in silica content contributes to the formation of various size (100–410 nm) of macroporous voids after hydrofluoric acid (HF) treatment. HF etching process was introduced to dissolve the silica and form voids in the structure of PI copolymer films. Compared with conventional PI films, air voids that were formed in the PI copolymer film reduced the dielectric from 4.40 to 1.86. The reduction in the dielectric constants can be explained in terms of creating silica particles that increase the presence of air voids after HF treatment. The thermal stability was stable up to 500 °C and the modulus change was confirmed with a dynamic mechanical analysis (DMA) to evaluate the effect of silica on thermal and mechanical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45982. more...
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- 2017
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40. Effects of dianhydrides on the thermal behavior of linear and crosslinked polyimides
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Kwangin Kim, Taewon Yoo, Hyemin Ha, Jinyoung Kim, and Haksoo Han
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Thermogravimetric analysis ,Materials science ,Polymers and Plastics ,Modulus ,General Chemistry ,Thermal expansion ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Differential scanning calorimetry ,chemistry ,Dynamic modulus ,Materials Chemistry ,Composite material ,Glass transition ,Polyimide ,Norbornene - Abstract
To determine the thermal characteristics of linear and crosslinked polyimides (PIs), BTDA, ODPA, and 6FDA were used to synthesize polyimides. Thermal degradation temperature and glass transition temperature of the resulting PIs were measured using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). To measure the change in modulus and coefficient of thermal expansion (CTE) depending on dianhydride structure, a dynamic mechanical analyzer (DMA) and thermo-mechanical analyzer (TMA) were used. The thermal degradation and glass transition temperature properties of linear PIs varied according to whether the linear chain adopted a bulky or flexible structure. Dynamic modulus and thermal expansion values of linear polyimides also showed good agreement with the TGA and DSC results. As we expected, linear polyimide with bulky 6FDA groups showed better thermal behavior than the flexible polyimides. Crosslinked polyimide nadic end-capped (norbornene) with a bulky dianhydride group had a lower thermal degradation temperature and higher CTE than flexible BTDA and ODPA polyimides. Our results indicate that the mobility of the dianhydride group affects the thermal behaviors of linear and crosslinked polyimides in different ways. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41412. more...
- Published
- 2014
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41. Continuous supercritical decrosslinking extrusion process for recycling of crosslinked polyethylene waste
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Soon Man Hong, Jun Yong Jung, Ji Wook Shin, Haksoo Han, Gi Joon Nam, Bum Ki Baek, and Chong Min Koo
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Materials science ,Polymers and Plastics ,Continuous reactor ,Plastics extrusion ,Thermosetting polymer ,General Chemistry ,Polyethylene ,Supercritical fluid ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Materials Chemistry ,Degradation (geology) ,Extrusion ,Methanol ,Composite material - Abstract
This work demonstrates that extrusion process can be used as a continuous reactor for the recycling of crosslinked polyethylene (XLPE) via supercritical methanol decrosslinking reaction. The multistage single screw extruder (L/D = 36, D = 40 mm) with methanol injection pump was customized for the continuous supercritical decrosslinking reaction. Reaction temperature was ranged from 360°C to 390°C. The amount of methanol was varied from 0 to 7 mL/min. The extruder provided the crosslinked polymers with the supercritical conditions of methanol during continuous process. The gel content of XLPE decreased with the increase in the reaction temperature and methanol content. Although XLPE experienced supercritical methanol for less than 2 min retention time in the continuous supercritical extruder, it was completely decrosslinked above 390°C at the methanol feeding rate of 7 mL/min. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41442. more...
- Published
- 2014
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42. Water‐sorption behaviors of poly(3,4′‐oxydiphenylene pyromellitimide) films depending on the thickness variation
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Chang Soo Han, Haksoo Han, and Joncchul Seo
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Polymers and Plastics ,Moisture regain ,Chemistry ,Kinetics ,Activation energy ,Water sorption ,Condensed Matter Physics ,Fick's laws of diffusion ,Chemical engineering ,Water uptake ,Polymer chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Diffusion (business) ,Polyimide - Abstract
The effect of film thickness on the water-sorption behaviors of poly(3,4′-oxydiphenylene pyromellitimide) (PMDA-3,4′ODA) films was gravimetrically investigated and interpreted with a Fickian diffusion model in films. The diffusion coefficient increased with increasing film thickness, whereas the water uptake and the activation energy decreased. Overall, the water-sorption behaviors of PMDA-3,4′ODA films are strongly dependent on the changes in morphological structure, which originated from the variation in the film thickness. As the film thickness increased, the molecular in-plane orientation decreased, consequently leading to the increased diffusion coefficient and decreased activation energy. In contrast, the water uptake decreased with increasing film thickness because of the increase in the out-of-plane packing order. The diffusion coefficient and activation energy were strongly dependent on the in-plane orientation in the films. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 669–676, 2001 more...
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- 2001
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43. Analysis of dimensionally stable copolyimide with a low-level residual stress
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Hyun Soo Chung, Wonbong Jang, Jaewook Hwang, and Haksoo Han
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Materials science ,Polymers and Plastics ,Dielectric ,Condensed Matter Physics ,BPDA ,Thermal expansion ,Crystallinity ,chemistry.chemical_compound ,chemistry ,Residual stress ,Materials Chemistry ,Stress relaxation ,Thermomechanical analysis ,Physical and Theoretical Chemistry ,Composite material ,Curing (chemistry) - Abstract
Copolyimide thin film, which has low-level stress and stress relaxation induced by water sorption, was characterized for potential applications as an encapsulant, a stress-relief buffer, and in interlayer dielectrics. The polyimides examined were poly(p-phenylene pyromellitimide) (PMDA-PDA) and poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA) as well as their random copolyimides with various compositions. These copolyimide films exhibited good combinations of physical and mechanical properties with low thermal expansion coefficients, residual stress, and moisture-induced stress-relaxation behavior by appropriately selecting the ratios of the dianhydride component. For these polyimides, the residual stress increased in the range of -8.1-7.5 MPa, whereas stress relaxation induced by water uptake decreased in the range of 10.3-4.7 MPa with increasing BPDA contents, respectively. The major factor in determining the magnitude of the stress behavior induced by both the thermal mismatch and water uptake in films should be the morphological factors such as chain rigidity, chain orientation, crystallinity, and microvoids. Their morphological structures were examined by wide angle X-ray diffraction and a prism coupler, and the thermal properties were measured using a dynamic mechanical thermal analyzer as well as thermomechanical analysis. Overall, the candidate for the low level stress buffer application from the PMDA/BPDA-PDA copolyimide was the 30/70 (= PMDA/BPDA in molar ratio) copolyimide. This copolyimide showed no residual stress after curing at 400 °C and relatively insensitive stress relaxation to ambient humidity. more...
- Published
- 2001
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44. Water diffusion studies in polyimide thin films
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Jongchul Seo and Haksoo Han
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Materials science ,Polymers and Plastics ,Chemical structure ,Diffusion ,General Chemistry ,Activation energy ,Surfaces, Coatings and Films ,Crystallinity ,Chemical engineering ,Chemical affinity ,Polymer chemistry ,Materials Chemistry ,Molecule ,Thin film ,Polyimide - Abstract
The water diffusion behaviors and activation energies of PDA- and ODA-based polyimide thin films were quite dependent on both the chemical structure and the morphological structure in the films. The water diffusion coefficients of polyimide thin films increased with increasing temperature. The activation energies varied in the range of 5.81 to 9.27 kcal/mol and were relatively higher for the PDA-based polyimide thin films than for the corresponding ODA-based polyimide thin films. For the PDA- and ODA-based polyimide films, the differences in the morphological structures and the chemical affinity to water molecules might be reflected directly on the water diffusion behaviors. The PDA-based polyimide films exhibited a relatively more ordered morphological structure (high crystallinity and good in-plane orientation) than that of the corresponding ODA-based polyimide thin films, which may serve as impenetrable obstacles for the water diffusion in the out-of-plane direction. Consequently, it may lead to a relatively slower water diffusion and high activation energy in the PDA-based polyimide thin films. Additionally, the PDA-based polyimide films with relatively lower chemical affinity showed relatively low diffusion coefficients and high activation energies. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 731–737, 2001 more...
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- 2001
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45. Water sorption behaviors of the BPDA-based polyimide films depending upon the structural isomers of diamine
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Haksoo Han, Jongho Jeon, Choonkeun Lee, Sunggook Park, and Jongchul Seo
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Absorption of water ,Materials science ,Polymers and Plastics ,Diffusion ,General Chemistry ,Crystal structure ,BPDA ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,Crystallinity ,chemistry ,Chemical engineering ,Diamine ,Polymer chemistry ,Materials Chemistry ,Thin film ,Polyimide - Abstract
For the biphenyltetracarboxylic dianhydride (BPDA)-based polyimide thin films, the water sorption behaviors were gravimetrically investigated by using a thin film diffusion analyzer. The water sorption behaviors of the polyimide thin films are quite different and strongly dependent upon the sort of polyimide. The diffusion coefficients of the polyimide thin films vary in the range of 1.6 × 10−10 to 12.4 × 10−10cm2/s and the water uptakes vary from 1.52 to 5.25 wt %. Both the diffusion coefficient and water uptake of the polyimide thin films are in the increasing order: BPDA-pPDA < BPDA-p,p′ODA < BPDA-p,m′ODA < BPDA-mPDA ∼ BPDA-p,p′DDS < BPDA-m,m′DDS. Specifically, the polyimide films with para-oriented linkages in backbone structure showed relatively lower diffusion coefficient and water uptake than the corresponding polyimide films with meta-oriented linkages because of the well-developed crystalline structure and good intermolecular chain ordering. In addition, the polyimide thin films having higher chain order showed relatively lower diffusion coefficient and water uptake. The crystallinity and intermolecular chain ordering in the morphological structure are critical parameters in controlling the water sorption behaviors of the polyimide thin films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2121–2127, 2001 more...
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- 2001
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46. Water-sorption behavior ofP-phenylene diamine-based polyimide thin films
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Haksoo Han, Anna Lee, Jongchul Seo, and Choonkeun Lee
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Morphology (linguistics) ,Materials science ,Polymers and Plastics ,Diffusion ,Intermolecular force ,Analytical chemistry ,General Chemistry ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,Phenylene ,Diamine ,Polymer chemistry ,Materials Chemistry ,Relative humidity ,Thin film ,Polyimide - Abstract
Four different p-PDA–based polyimide thin films were prepared from their respective poly(amic acid)s through thermal imidization at 400°C: poly(p-phenylene pyromellitimide) (PMDA-PDA); poly(p-phenylene biphenyltetra carboximide) (BPDA-PDA); poly(p-phenylene 3,3′,4,4′-oxydiphthalimide) (ODPA-PDA); and poly(p-phenylene 4,4′-hexafluoroisopropylidene diphthalimide) (6FDA-PDA). Water-sorption behaviors of polyimide films were gravimetrically investigated at 25°C and 22–100% relative humidity by using the modified electromicrobalance (Thin Film Diffusion Analyzer). The diffusion coefficients of water for the polyimides varies in the range of 1.6 to 10.5 × 10−10 cm2/s, and are in the increasing order: BPDA-PDA < PMDA-PDA ∼ ODPA-PDA < 6FDA-PDA. The water uptakes of polyimides vary from 1.46 to 5.80 wt %, and are in the increasing order: BPDA-PDA < ODPA-PDA < 6FDA-PDA < PMDA-PDA. The water-sorption behaviors for the p-PDA–based polyimides are closely related to the morphological structure; specifically, the diffusion coefficients in p-PDA–based polyimide thin films are closely related to the in-plane orientation and mean intermolecular distance, whereas the water uptakes are affected by the packing order. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1315–1323, 2000 more...
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- 2000
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47. Stress behaviors and thermal properties of polyimide thin films depending on the different curing process
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Jonghwae Lee, Haksoo Han, Hyun Soo Chung, Wonbong Jang, and Yong Gun Shul
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Polymers and Plastics ,Chemistry ,Condensed Matter Physics ,Solvent ,Stress (mechanics) ,Boiling point ,Residual stress ,Thermal ,Materials Chemistry ,Physical and Theoretical Chemistry ,Thin film ,Composite material ,Anisotropy ,Polyimide - Abstract
The effect of high boiling point solvent on the residual stress behaviors of semiflexible structure poly(4,4′-oxydiphenylene pyromellitimide) (PMDA-ODA) and pseudo-rodlike poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA) polyimide was investigated. As a solvent, a mixed solution of 20 wt % cyclohexyl-2-pyrrolidone (CHP; bp = 307 °C) and 80 wt % n-methyl-2-pyrrolidone (NMP; bp = 202 °C) was used. The effects of solvent system and imidizing history on the morphological structure, as well as residual stress, were significantly high in the BPDA-PDA having high chain rigidity, but relatively low in the semiflexible PMDA-ODA with low chain rigidity. In addition, rapidly cured films prepared from PAA (NMP/CHP) showed higher residual stress and a lower degree of molecular anisotropy than slowly cured film imidized from PAA (NMP). This was induced by high chain mobility in polyimide thin films prepared from PAA (NMP/CHP) during the thermal cure process. Therefore, molecular anisotropy, depending on the solvent system and imidizing history, might be one of the important factors leading to low residual stress in polyimide thin films. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2879–2890, 2000 more...
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- 2000
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48. Water sorption and activation energy in polyimide thin films
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Jongchul Seo, Haksoo Han, Jongho Jeon, and Yong Gun Shul
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Range (particle radiation) ,Absorption of water ,Materials science ,Polymers and Plastics ,Diffusion ,Chemical structure ,Activation energy ,Condensed Matter Physics ,Crystallinity ,Chemical engineering ,Polymer chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Thin film ,Polyimide - Abstract
The water sorption behavior and the activation energy were investigated for various chemical structure polyimide thin films; BPDA-PDA, BPDA-ODA, PMDA-ODA, and 6FDA-ODA. The activation energy for the water diffusion varied in the range of 5.53 to 9.27kcal/mol, and was in the increasing order: BPDA-PDA < BPDA-ODA < PMDA-ODA < 6FDA-ODA. BPDA-PDA and BPDA-ODA polyimide films showed relatively well-ordered morphological structure, which results in relatively low diffusion coefficient and high activation energy. It was found that the diffusion coefficient and the activation energy are significantly related to the in-plane orientation, crystallinity, and packing order in the polyimide thin films. The morphological structure was predominant factors for the water diffusion coefficient and activation energy in the polyimide thin films. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2714–2720, 2000 more...
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- 2000
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49. The effect of curing history on the residual stress behavior of polyimide thin films
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Hyun Soo Chung, Haksoo Han, and Yung-Il Joe
- Subjects
Materials science ,Polymers and Plastics ,Annealing (metallurgy) ,Intermolecular force ,General Chemistry ,Lower temperature ,Surfaces, Coatings and Films ,Residual stress ,Materials Chemistry ,Wafer ,Thin film ,Composite material ,Curing (chemistry) ,Polyimide - Abstract
The effect of curing history on the residual stress behaviors in semiflexible structure poly(4,4′-oxydiphenylene pyromellitimide) (PMDA–ODA) and rigid structure poly(p-phenylene biphenyltetracarboximide) (BPDA–PDA) polyimide was investigated. Depending upon the curing history and different structures of polyimide, the residual stress behaviors and the morphology of polyimide thin films were detected in situ by using a wafer bending technique and wide angle X-ray diffraction (WAXD), respectively. For the rigid structure BPDA–PDA polyimide, the residual stress and the slope decreased from 11.7 MPa and 0.058 MPa/°C to 4.2 MPa and 0.007 MPa/°C as the curing temperature increased, and the annealing process is done. However, for the semiflexible structure PMDA–ODA, the change of the residual stress and the slope was relatively not significant. In addition, it was found that the cured polyimide prepared at a higher temperature with a multistep curing process showed a higher order of chain in-plain orientation and packing order than does the polyimide film prepared at a lower temperature with a one-step curing process. These residual stress behaviors of polyimide thin films show good agreement with WAXD results, such as polyimide chain order, orientation, and intermolecular packing order, due to curing history. Specifically, it shows that the effect of curing history on residual stress as well as morphological change was significant in rigid BPDA–PDA polyimide but, not in semiflexible PMDA–ODA polyimide. Therefore, it suggests that the morphological structure depends upon curing history, and the polyimide backbone structure might be one of important factors to lead the low residual stress in polyimide thin films. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3287–3298, 1999 more...
- Published
- 1999
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50. Synthesis and characterization of new polyimides containing calix[4]arenes in the polymer backbone
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Haksoo Han, Jongchul Seo, Gil Tae Hwang, Moonhor Ree, Byeang Hyean Kim, Tae Joo Shin, and S. I. Kim
- Subjects
chemistry.chemical_classification ,Materials science ,Polymers and Plastics ,Comonomer ,Organic Chemistry ,Polymer ,chemistry.chemical_compound ,Monomer ,Membrane ,chemistry ,Diamine ,Calixarene ,Polymer chemistry ,Materials Chemistry ,Organic chemistry ,Thermal stability ,Polyimide - Abstract
Two diaminocalix[4]arene monomers were synthesized from p-tert-butylcalix[4]arene through a 4-step reaction sequence. New copoly(amic acid)s containing calix[4]arene moieties on the polymer backbone were successfully synthesized in N-methyl-2-pyrrolidone by polycondensations of 4,4′-oxydiphthalic anhydride (ODPA) with the diaminocalix[4]arene monomers using 4,4′-oxydiphenylene diamine (ODA) as a comonomer. These copoly(amic acid)s were soluble in aprotic polar solvents, so that they can be processed in various ways. The copoly(amic acid) precursors were thermally converted to the corresponding copolyimides in films. The copolyimide films are amorphous, but insoluble in common solvents. They are thermally stable up to 366°C. The copolyimides exhibit relatively high TEC's, low Tg's, low refractive index, low dielectric constant, low optical anisotropy, low dielectric anisotropy, and low water uptake, compared to those of conventional ODPA-ODA polyimide. These property characteristics were interpreted in regard to bulky, cone-like calix[4]arene moieties and their effects on the chain conformation and morphological structure. The processability and property characteristics support that both of the copolyimides containing calix[4]arene moieties are potential candidate materials suitable for membranes, antioxidant additives, chemical sensor devices, and microelectronic devices. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2013–2026, 1999 more...
- Published
- 1999
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