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Yusuke Tsuda, Syouma Kawabata
2014 Volume 27 Issue 3 Pages
277-282
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Novel diamine monomers having hydrophobic groups were synthesized from natural products such as ferulic acid and γ-oryzanol. The novel polyimides and copolyimides were synthesized from 3,4’-ODPA as a dianhydride, above diamines having natural product skeleton, and DDE as a diamine co-monomer by two step polymerization systems. The thin films of obtained polyimides were irradiated by UV light (λ
max; 254 nm), and the contact angles for the water decreased from 90- 100° (hydrophobicity) to minimum 35° (hydrophilicity) in proportion to irradiated UV light energy. The tendency in this wettability change is larger in the case of polyimides based on a γ-oryzanol skeleton than in the case of polyimides based on a ferulic acid skeleton. From the result of surface analyses (ATR, XPS, AFM), it is recognized that the hydrophobic alkyl groups on the polyimide surface decrease and the hydrophilic groups such as hydroxyl groups and carboxyl groups generate on their surface.
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Wataru Neyatani, Hirokazu Furue
2014 Volume 27 Issue 3 Pages
283-286
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Blue phase is an attractive liquid crystal because of the 3-dimensional nano-structure. We have tried to obtain the blue phase using photocurable mesogenic monomers and chiral dopant and solidify the blue phase structure by irradiation of ultra-violet light. Furthermore, we have examined the mechanical strength of the solidified blue phase. As a result, we found that the appearance of blue phase strongly depended on the combination of mesogenic monomers and the concentration of chiral dopant, and then the blue phase structure could remain even after the polymerization. In the mechanical strength, the solidified blue phase samples are more fragile than the solidified samples which have been photocured in the choresteric phase. This fact may result from a discontinuous lattice structure including defects, i.e. platelet texture, as seen in microscopic texture observation.
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Rumiko Yamaguchi, Shintaro Sakurai
2014 Volume 27 Issue 3 Pages
287-290
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Electro-optical properties have been investigated as a function of cell thickness in a reverse mode cell which shows a transparent off-state and a light scattering on-state. The cell is prepared by using a nematic liquid crystal (LC) and a photo-reactive mesogen. A driving voltage and a contrast ratio of this device strongly depend on a cell thickness and there is a trade-off relationship between them. We have reported that the cell thickness dependence in the reverse mode LC cell is different from that in a normal scattering mode polymer dispersed LC with normal scattering mode. The turbidity in voltage on-state is investigated as a function of cell thickness and a simple model with polymer rich and poor layers in the cell is proposed to analyze scattering properties. The low driving voltage is compatible with the high contrast ratio by control the cell thickness and the morphology of polymer network.
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Munehiro Kimura, Yukihiro Nagataki, Keisuke Ueda, Takuya Yamamoto
2014 Volume 27 Issue 3 Pages
291-296
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Slit coater method as a fabrication process for flexible type liquid crystal display (LCD) is one of a suitable technique because of its unnecessity of thermal and vacuum process. In our previous study, planar and/or vertical alignment properties for liquid crystal (LC) by means of the slit coater method, where the doped reactive mesogens was UV-polymerized and played a role of LC alignment film, were demonstrated. In this paper, a dependence of pretilt angle on the UV irradiation condition such as the irradiation energy and wavelength was investigated.
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Jian Zhang, Chih-Yu Hsu, Masayoshi Higuchi
2014 Volume 27 Issue 3 Pages
297-300
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Ru(II)-based metallo-supramolecular polymers with different counter anions (Cl
-, (CF
3SO
2)
2N
-, CF
3SO
3-, BF
4-, ClO
4-, PF
6- and CO
32-) were prepared by anion exchange reaction in the film state. In the UV-vis. spectra, the MLCT absorption was observed around 510 nm and the maximum wavelength was slightly different among the polymers. The polymers with “soft” counter anions such as (CF
3SO
2)
2N
-, CF
3SO
3-, ClO
4- and PF
6- showed a reversible redox wave based on the redox of Ru(II)/(III). It was revealed that the redox is diffusion-controlled. The polymers with (CF
3SO
2)
2N
-, CF
3SO
3-, ClO
4-, PF
6- and BF
4- showed reversible EC behavior. The polymers with (CF
3SO
2)
2N
- and ClO
4- exhibited the highest durability and the quickest response (3.69/0.98 s), respectively, among the polymers. The polymer with (C
3SO
2)
2N
- has the highest color efficiency (270.3 cm
2 C
-1). These results suggested that the hardness/softness of counter anions greatly influences the EC properties of the Ru(II)-based metallo-supramolecular polymers.
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Haruhisa Akiyama, Masaru Yoshida, Hideyuki Kihara, Yasuo Norikane, Rei ...
2014 Volume 27 Issue 3 Pages
301-305
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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The light induced phase transition and reversible adhesive function were investigated for a range of D-mannitol derivatives partially substituted with multi-azobenzenes bearing free hydroxyl groups. Irradiation with UV and visible light induced liquefaction and solidification of the compounds, which adhered glass plates. Further, the adhesion force could be changed reversibly upon irradiation with light. Moreover, the adhesion forces were larger than those of the fully substituted compound.
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Masakazu Nakamura, Ryosuke Matsubara
2014 Volume 27 Issue 3 Pages
307-316
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Device physics in organic thin-film transistors (OTFTs) have been extensively studied along with the efforts to improve device performance and to develop their applications. Among many promising organic semiconducting materials, pentacene has been a benchmark in this research field. Understanding the bottlenecks of carrier transport in pentacene OTFTs is therefore important to maximize the performance of OTFTs. In this paper, we summarize our knowledge on the bottlenecks against carrier transport in practical polycrystalline organic thin films: extrinsic factors that disturb the carrier transport in OTFTs, intrinsic structure and properties, equations to express the overall carrier mobility in polycrystalline electronic structures.
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Yoshihito Kunugi, Ayami Maeda, Teppei Arakawa, Kazuo Okamoto
2014 Volume 27 Issue 3 Pages
317-320
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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We successfully fabricated single crystal OFETs based on alkylphenyl substituted 21DNFU derivatives that are highly soluble in common organic solvents. The single crystal OFETs showed typical p-type OFET characteristics, and the field-effect mobility of the holes was estimated to be 0.2 cm
2V
-1s
-1 with an I
on/I
off ratio of 10
3 for 3P-21DNFU and 5P-21DNFU. The field-effect characteristics of the single crystal OFETs were strongly affected by the chain lengths of the alkyl groups and packing structures of the molecules.
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Masashi Mamada, Taisuke Uemura, Ryo Teraoka, Daisuke Kumaki, Shizuo To ...
2014 Volume 27 Issue 3 Pages
321-326
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Two newly developed narrow bandgap polymers containing benzobis(thiadiazole) (BBT) have been synthesized using the Stille coupling reaction. The polymers showed absorption in the near infrared region due to strong charge-transfer interactions in the donor-acceptor (D-A) units, suggesting a rigid planarized structure. Although both the HOMO-LUMO levels of the polymers lie close to the work function of gold electrodes, a BBT-quaterthiophene polymer showed only p-type semiconducting behavior. In addition, the dominant charge-carrier type is holes even in BBT-thiazole-thiophene polymers, which consists mainly of acceptor units, and indicates that the thiophene ring in these polymers has a strong influence on the charge transport properties.
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Tatsuo Mori, Kazuhiro Imai, Hideo Furuhashi, Takao Nishikawa
2014 Volume 27 Issue 3 Pages
327-332
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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We have improved lifetime and low driving voltage of the device using an electrode modified by a silane-based fluorinated self-assembled monolayer (FSAM) on ITO (transparent electrode). In the process of fabricating organic light-emitting diodes (OLEDs) devices using Ag or Cu electrode modified by a fluorinated thiol-based SAM, anomalous current saturation phenomena was observed on current-voltage characteristics only when using a thiol-SAM-modified Cu anode. When the performance of the OLED with thiol-SAM-modified Cu or Ag anode were compared with that of the OLED with FSAM-modified ITO, the thiol-SAM-modified Ag anode showed more excellent performance than the FSAM-modified ITO. The OLED with thiol-SAM-modified Cu anode also showed the strange EL efficiency behavior in the saturation current region.
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Heisuke Sakai, Hae-Jeong Cheong, Takehito Kodzasa, Hideo Tokuhisa, Kaz ...
2014 Volume 27 Issue 3 Pages
333-337
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Memory characteristics of organic field-effect transistors (OFETs) fabricated using poly(γ-methyl-L-glutamate) (PMLG) and poly(ε-benzyloxycarbonyl-L-lysine) [PLys(z)] as gate dielectrics are investigated. The origin of difference in the memory retention property in the transfer characteristics of the OFETs is investigated by thermally stimulated depolarized current (TSDC) and dielectric spectra measurements for the PLys(z) and PMLG films. TSDC measurements reveal that the depolarization of the PLys(z) film is mainly dominated by a single relaxation process around room temperature, but that of the PMLG film is not dominated by a relaxation process. Further, the PLys(z) film shows dielectric dispersion near room temperature, but the PMLG film does not show any dispersion. This causes difference in the electric characteristics of OFETs.
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Hea Jeong Cheong, Nobuko Fukuda, Shintaro Ogura, Heisuke Sakai, Manabu ...
2014 Volume 27 Issue 3 Pages
339-342
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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We have demonstrated a high-efficiency microwave annealing technology that can enhance the electrical characteristics of TFTs prepared using high-viscosity IGZO precursors. The process is advantageous for short-time annealing high-viscosity precursor-film.
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Kazuhiko Segi, Shigeki Naka, Hiroyuki Okada
2014 Volume 27 Issue 3 Pages
343-346
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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We have investigated improvement in performance of blue sensitive organic photodiodes using a pyrazol derivative. Improved performance was obtained in the device using BBOT as an acceptor material. In addition, insertion of ultra-thin rubrene layer at donor/acceptor interface was effective for improvement of the exciton separation.
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Yoshito Sasada, Fumiaki Kato, Kenichi Oyaizu, Hiroyuki Nishide
2014 Volume 27 Issue 3 Pages
347-350
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Poly(3,4-ethylenedioxythiophene) (PEDOT), for use as a hole-transporting layer in dye-sensitized solar cells (DSSCs), was synthesized via in-situ polymerization using a gas-phase oxidant. Highly volatile iodine was used as the gas-phase oxidant to fill up a porous TiO2 substrate. The conductivity of PEDOT increased to 0.9 S/cm upon the addition of a base, 4-tert-butylpyridine, to the monomer solution. A solid-state DSSC was fabricated using PEDOT as the hole-transporting layer, which displayed photo-electric conversion.
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Seijiro Fukuta, Tomoyuki Koganezawa, Masatoshi Tokita, Susumu Kawauchi ...
2014 Volume 27 Issue 3 Pages
351-356
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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The detailed morphology was investigated on 1,3,4-oxadiazole (OXD) and 1,3,4-thiadiazole (TD) containing π-conjugated polymer films based on synchrotron GIXS measurements. Grazing-incidence wide-angle X-ray scattering (GIWAXS) proved that TD-containing polymers showed face-on orientation, which is, in general, favor for the polymer solar cell (PSC) application. Density function theory calculation suggests that the favorable orientation is probably induced by the curvature of TD-containing polymer main chains. In addition, the bulk-heterojunction structure were evaluated by grazing-incidence small-angle X-ray scattering (GISAXS) and atomic force microscope (AFM). As a result, it was also found that the π-π stacking distance, correlation length and PC
61BM cluster size had good relationship with the short circuit current density (J
sc) and fill factor (FF) in the PSC application.
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Nobuhiro Ide, Kazuyuki Yamae, Varutt Kittichungchit, Hiroya Tsuji, Mas ...
2014 Volume 27 Issue 3 Pages
357-361
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Non-radiation mode of OLED device was reduced by optimizing the distance between emissive layers to the metal cathode. Light distribution of OLED and optical properties of a light outcoupling substrate based on high refractive index microstructures were adjusted to achieve the better combination of the OLED device with the substrate. Those advanced optical design decreased non-radiative evanescent mode and waveguide mode, and realized a white OLED device with quite high light outcoupling efficiency of at least 56 % and outstandingly high efficacy of 133 lm/W at 1,000 cd/m
2.
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Satoru Ohisa, Naoya Takahashi, Yong-Jin Pu, Junji Kido
2014 Volume 27 Issue 3 Pages
363-367
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Light scattering structures for light out-coupling enhancement in organic light emitting devices (OLEDs) were fabricated by self-organization of poly[(9,9-di-n-octylfluorenyl-2,7diyl)-alt-(benzo[2,1,3]-thiadiazol-4,8-diyl)] (F8BT). The F8BT film spin-coated from chloroform or THF solution showed smooth surface, while the film spin-coated from the mixture of chloroform/1,4-dioxane or THF/1,4-dioxane solution showed rough wavy surface. Fourier transformation of the waves in the rough F8BT films exhibited large components having the wavelength corresponding to near-infrared region. Orange-emitting OLEDs were fabricated on the rough F8BT films. Indium zinc oxide (IZO) and organic layers were deposited by either evaporation or spin-coating. The surface roughnesses of the evaporated organic layers were same as the surface roughness of the F8BT. On the other hand, the spin-coated organic layer reduced the roughness of the F8BT. Both in the evaporated and the spin-coated OLEDs, the external quantum efficiencies of OLEDs were increased by 1.2 times compared with those of the OLEDs without the F8BT, indicating that the F8BT served as light scattering structure to enhance light out coupling.
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Yasushi Sasai, Akihiro Komatsu, Shin-ichi Kondo, Yukinori Yamauchi, Ma ...
2014 Volume 27 Issue 3 Pages
369-372
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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The effects of argon plasma irradiation on pAAc-grafted PS substrate were investigated. The argon plasma irradiation caused the efficient decarboxylation in pAAc brushes so that the surface hydrophilicity was significantly changed. The protein antifouling properties on pAAc-grafted PS substrate were lost even by short plasma irradiation so that the surface was changed to highly favorable for protein adsorption. These results are useful for controlling the protein adsorption onto pAAc-grafted materials and expected to be used for the development of microarray such as protein and cell array using pAAc-grafted PS as a substrate.
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Yuichi Mine, Tatsuyuki Nakatani, Keishi Okamoto, Shintarou Hara, Kenta ...
2014 Volume 27 Issue 3 Pages
373-378
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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To examine the effects of hydrogen amount-altered biomimetic DLC film, osteoblastic MC3T3-E1 cells and osteoclastic RAW264.7 cells were cultured on titanium (Ti) disks coated with or without DLC including various amount of hydrogen. The amount of hydrogen in DLC film is reduced from 20.9% to 0.8%. Real-time quantitative reverse transcriptase-polymerase chain reaction analysis showed that typeⅠcollagen mRNA in MC3T3-E1 cells cultured on specific hydrogen-containing DLC coated Ti disks was significantly higher than those of control Ti disks. In addition, specific hydrogen-containing DLC coated Ti disks significantly inhibited the expression of TRAP mRNA in RANKL-treated RAW264.7 cells. These results, taken together, suggested that biomimetic DLC altered osteoblast and osteoclast differentiation, which could promise long-term success of implant therapy.
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Osamu Takai
2014 Volume 27 Issue 3 Pages
379-384
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Liquid-phase plasma is not well known compared with gas-phase plasma. We name the liquid-phase plasma “solution plasma” because of the generation of different plasmas by choosing the combinations of solvents and solutes in solutions. We can generate a glow discharge with a pulsed power generator by controlling several parameters for the ignition of the discharge. It is important to generate the glow discharge in solutions, which realizes the formation of a new reaction field at almost room temperature. We measured the basic physical and chemical properties of solution plasma by time-resolved optical spectroscopy and coherent ant-Stokes Raman spectroscopy (CARS). The solution plasma is applicable to nanomaterials synthesis, surface modifications, water treatment, sterilization, decomposition of cellulose and toxic compounds, and so far.
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Shin-ichi Kondo, Masako Suzuki, Yasushi Sasai, Yukinori Yamauchi, Masa ...
2014 Volume 27 Issue 3 Pages
385-388
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Inclusion complex between Per-6-ABCD-Cy3 (per-6-amino-β-cyclodextrin labeled with Cy3) and Per-6-ABCD-Cy5 immobilized onto the self-assembled phospholipid layer was formed, so that FRET was observed. The inclusion complex was decomposed by the addition of PEG. It was suggested that PEG could be detected with the present film and that the amount of PEG might depend on the decrease of fluorescence intensity. We are now actively elaborating the high sensitive detection of PEG with the present LDPE-StA-PC-SA film immobilizing Per-6-ABCD-Cy3 (self-assembled PC layer incorporating StA) and Per-6-ABCD-Cy5.
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Yukinori Yamauchi, Masayuki Kuzuya, Yasushi Sasai, Shin-ichi Kondo
2014 Volume 27 Issue 3 Pages
389-392
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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We attempted to control the drug release from a double-compressed tablet containing theophylline core with outer layer consisted of HPMCAS-myo-Inositol and HPMCP-Lactose by plasma-irradiation. By use of difference in degradation properties of organic compounds, the oxygen plasma- irradiation varied outer layer so as to cause release of drugs at different rates, depending on conditions chosen for plasma operation. From the SEM analyses, it was concluded that concurrent occurrence of cross-link reaction and the micropores formation on outer layer converted rapid-release system into sustained-release system. As described, it was shown that new examples that cellulose derivatives widely used as pharmaceutical aids would be also applied to a outer layer polymer of the double-compressed tablet to fabricate a system for targeted release of various kinds of drugs in the lower sections of the small or large intestine by making use of plasma techniques.
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Takao Ono, Ryo Iizuka, Takanori Akagi, Takashi Funatsu, Takanori Ichik ...
2014 Volume 27 Issue 3 Pages
393-398
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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In plasma processing, UV photons generate damage deep in the bulk of transparent materials such as amorphous polymers and glass. In this article, we propose the use of total internal reflection fluorescence microscopy for the nondestructive and highly sensitive detection of UV-induced deep bulk damage and for the first time demonstrate the three-dimensional profiling of UV penetration and optical damage production inside amorphous perfluorocarbon films. Weak fluorescence from damaged molecules, whose original chemical structure was altered through bond breaking and reconstruction, was detected up to several hundred nanometers below the surface after exposure to argon plasma.
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Masafumi Jinno, Yoshihisa Ikeda, Hideki Motomura, Yugo Kido, Kunihide ...
2014 Volume 27 Issue 3 Pages
399-404
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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The authors parametrically investigated gene transfer process with a micro capillary discharge. Several factors and the time scale at which they become effective were studied. The conclusion is that half of transfections occur during plasma irradiation and the other half occur after plasma irradiation is stopped. As the electric field and current become zero after plasma irradiation is terminated, we conclude that during that period radical species are necessary for the transfection.
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Kosei Satahira, Seisaku Ohshiro, Keiko Nakamura, Seisiro Ito, Tatsuhik ...
2014 Volume 27 Issue 3 Pages
405-408
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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The relationship between PCI color shift and W/FM was examined. And the possibility of the universal quantification for the action of O (
3P or
1D) and O
2 (
1Δ
g) in oxygen plasma was investigated using two different types of reactors, a bell-jar reactor (A-type) and a tubular reactor (B-type). There seems to exist a critical W/FM, (W/FM)c, at which neither green shift nor red shift can occur. The values of (W/FM)c for A- and B-type reactors were around 1.4 GJ/kg-O
2 and 0.6 GJ/kg-O
2, respectively. From the results of the spectroscopic approach, several peaks that attributed to atomic oxygen (
1D -
3P) and molecular oxygen (
1Σ
g+ -
3Σ
g-) were observed. The relationship between emission strength ratio of O
(777 nm) /O
2 (762 nm) and W/FM suggested that the tendencies seen in Figure 6 were characteristics peculiar to each plasma reactor, and it could be explained the reason why the red shift and green shift occured at different W/FM by different reactors. Also, this proves that PCI is available to detect the action of atomic and molecular oxygen separately.
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Kei Oya, Ryota Watanabe, Shunsuke Sasaki, Hajime Hiraga, Yasutaka Ohni ...
2014 Volume 27 Issue 3 Pages
409-414
Published: July 08, 2014
Released on J-STAGE: September 05, 2014
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Polyethylene terephthalate (PET) has excellent transparency, heat resistance, electrical insulation, chemical resistance, and wear resistance. With a miniaturization and multifunctionalization of an industrial product, control of material surface and interface has become important. Active oxygen species were generated via 185/254 nm UV lights irradiation under conditions of high and low humidity, and PET films were exposed to the active oxygen species with these UV lights. Changes in their surface characteristics were evaluated. Contact angle of water droplet on the PET film surface and surface roughness after the treatment in the high humidity condition were higher than those in the low humidity condition, and transmittance of the PET film within a region of the visible light after the treatment in the high humidity condition decreased compared to that in the low humidity condition. The PET film surface can be modified more gently in the low humidity condition than in the high humidity condition.
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