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Journal Articles

Chain dynamics in spin-coated films of poly(methyl methacrylate) in a solvent annealing process

Aoki, Hiroyuki

Polymer Journal, 51(6), p.611 - 616, 2019/06

 Times Cited Count:4 Percentile:25.74(Polymer Science)

Journal Articles

Molecular dynamics simulation of telomeric single-stranded DNA and POT1

Kaburagi, Masaaki; Yamada, Hironao*; Miyakawa, Takeshi*; Morikawa, Ryota*; Takasu, Masako*; Kato, Takamitsu*; Uesaka, Mitsuru*

Polymer Journal, 48(2), p.189 - 195, 2016/02

 Times Cited Count:4 Percentile:18.27(Polymer Science)

We performed molecular dynamics (MD) simulations of telomeric single-stranded DNA and POT1 for 100 ns. The distance between $$C_alpha$$ (POT1) and O5' (telomeric ssDNA) is calculated to verify the binding system for 100 ns MD. We then calculated the distance between the bases of telomeric DNA ends and the root mean square deviation and gyration radius in single and binding states. We compared the root mean square fluctuations between single and binding states and calculated the number of hydrogen bonds between POT1 and telomeric DNA. There are many hydrogen bonds between Gln94 and the first guanine of the closest TTAGGG sequence in telomeric single-stranded DNA. These Gln94 and the guanine have a large difference in root mean square fluctuation between single and binding states. We found that Gln94 and guanine are important components of the binding system, and they are related to its stability.

Journal Articles

Combining small-angle and intermediate-angle neutron scattering to study the hierarchical structure in microbial cellulose

Zhao, Y.; Koizumi, Satoshi

European Polymer Journal, 66, p.437 - 443, 2015/05

 Times Cited Count:2 Percentile:7.92(Polymer Science)

Journal Articles

Pulse radiolysis study on a highly sensitive chlorinated resist ZEP520A

Hosaka, Yuji*; Oyama, Tomoko; Oshima, Akihiro*; Enomoto, Satoshi*; Washio, Masakazu*; Tagawa, Seiichi*

Journal of Photopolymer Science and Technology, 26(6), p.745 - 750, 2013/12

 Times Cited Count:10 Percentile:36.05(Polymer Science)

ZEP520A is one of the most popular positive electron beam (EB) resists used in research and photomask fabrication owing to its excellent properties. Herein, EB-induced initial reactions of ZEP520A were investigated via pulse radiolysis (EB energy: 28 MeV, time resolution: 10 ns). Dissociative electron attachment and formation of a charge transfer complex were definitive contributing factors to the efficient degradation of ZEP520A. Furthermore, products induced by direct ionization of ZEP520A were observed in a highly concentrated ZEP520A solution in tetrahydrofuran, suggesting that initial reactions in the ZEP520A solid film that are induced only by direct ionization could be simulated via pulse radiolysis in specific solutions.

Journal Articles

Nanoscale structures of radiation-grafted polymer electrolyte membranes investigated via a small-angle neutron scattering technique

Sawada, Shinichi; Yamaguchi, Daisuke; Putra, A.; Koizumi, Satoshi*; Maekawa, Yasunari

Polymer Journal, 45(8), p.797 - 801, 2013/08

 Times Cited Count:9 Percentile:32.81(Polymer Science)

The nanoscale structures of graft-type polymer electrolyte membranes based on poly(ethylene-co-tetrafluoroethylene) (ETFE) films were investigated using a small-angle neutron scattering (SANS) technique. For comparison, SANS measurements were also performed on two precursor materials, the original ETFE film and polystyrene (PS)-grafted films. The SANS profiles of the grafted films showed shoulder peaks at a d-spacing of approximately 30 nm, which were attributed to the PS grafts introduced into the amorphous phases between the ETFE lamellar crystals. In the ETFE PEMs, the spacing of the polystyrene sulfonic acid (PSSA) grafts and ETFE crystals increased because the graft regions were enlarged by the volume of the attached sulfonic acid groups. Interestingly, the graft / crystal stack spacing in the PEMs did not increase from the dry- to fully-hydrated states. This finding implies restricted water absorption in the PSSA grafts between the ETFE lamellar crystals.

Journal Articles

Effects of crosslinker density on the polymer network structure in poly-$$N$$,$$N$$-dimethylacrylamide hydrogels

Fukazawa, Tomoko*; Ikeda, Naohiro*; Tabata, Mayu*; Hattori, Masataka*; Aizawa, Mamoru*; Yunoki, Shunji*; Sekine, Yurina

Journal of Polymer Science, Part B; Polymer Physics, 51(13), p.1017 - 1027, 2013/07

 Times Cited Count:26 Percentile:69.63(Polymer Science)

Journal Articles

Effect of partial delignification of kenaf bast fibers for radiation graft copolymerization

Mohamed, N. H.*; Tamada, Masao; Ueki, Yuji; Seko, Noriaki

Journal of Applied Polymer Science, 127(4), p.2891 - 2895, 2013/02

 Times Cited Count:12 Percentile:42.04(Polymer Science)

Changes in residual lignin of kenaf bast fiber with acidic chlorite using various parameters were conducted to produce partial delignified fiber for radiation graft copolymerization. The effect of delignification temperature, operating time as well as chlorite doses on the residual lignin of the fibers has been reported. Results obtained indicated that the optimal delignification was achieved at 80$$^{circ}$$C for 6h with 0.5% chlorite. The reduction in density, size and tensile strength were attributed to the increase of removal of lignin from the fiber. Radiation induced emulsion graft copolymerization of 4-chloromethyl styrene (CMS) on partial delignified kenaf with residual lignin $$<$$2% resulted in higher degree of grafting of about 143% as compared to the undelignified fiber, which showed the absence of grafting degree.

Journal Articles

$$gamma$$-ray irradiated organic thin film transistors based on perfluoropentacene with polyimide gate insulator

Takayanagi, Yutaro*; Ouchi, Hirokuni*; Duan, Z.*; Okukawa, Takanori*; Yanagi, Yuichiro*; Yoshida, Akira*; Taguchi, Mitsumasa; Hirao, Toshio; Nishioka, Yasushiro*

Journal of Photopolymer Science and Technology, 25(4), p.493 - 496, 2012/08

 Times Cited Count:0 Percentile:0.01(Polymer Science)

Organic thin film fields effect transistors are expected to be used in spacecrafts/satellites because they can realize large-size, mechanical flexibility, light weight and low-cost devices. N-channel field effect transistors with a Si/polyimide(PI)/perfluoropentacene/Au structure were fabricated, and irradiated with $$gamma$$-ray from Co source. The changes of the drain current vs. source/drain voltage characteristics were measured after every 200 Gy in silicon Gy(Si) irradiations up to the total dose of 1200 Gy(Si). The drain current gradually increased up to the total dose of 1200 Gy(Si). The threshold voltage decreased up to 400 Gy(Si), and gradually recovered above 600 Gy(Si). The mobility was almost unchanged up to 1200 Gy(Si). Those behaviors were explained by accumulation of positive trapped charge within the gate insulator PI near the interface. Evidence for the accumulation of interface traps was hardly observed.

Journal Articles

Microprocessing of arched bridge structures with epoxy resin by proton beam writing

Takano, Katsuyoshi*; Asano, Atsushi*; Maeyoshi, Yuta*; Marui, Hiromi*; Omichi, Masaaki*; Saeki, Akinori*; Seki, Shu*; Sato, Takahiro; Ishii, Yasuyuki; Kamiya, Tomihiro; et al.

Journal of Photopolymer Science and Technology, 25(1), p.43 - 46, 2012/07

 Times Cited Count:2 Percentile:7.54(Polymer Science)

Journal Articles

Surface modification of vulcanized rubber by radiation grafting, 2; Improvement in performance of wiper rubber

Mizote, Norihito*; Katakai, Akio; Tamada, Masao

Journal of Applied Polymer Science, 123(4), p.2172 - 2176, 2012/02

 Times Cited Count:4 Percentile:15.13(Polymer Science)

Surface of natural rubber was modified by radiation-induced grafting of 2-hydroxyethyl methacrylate (HEMA) to improve the properties of surface hardness, dry friction, wiping performance, and wear duration. The composition ration of HEMA to rubber was controlled from 0.29 to 0.93 by changing HEMA concentration and dose in graft polymerization. When this composition ration was higher than 0.7, the surface hardness was higher than 64 and the coefficient of dry friction lower than 0.65. Those values became better than those of commercially available chlorinated-rubber in terms of wear and friction against glass. The resulting wear resistance was 10 times higher than chlorinated rubber. However, the surface hardness in wet state was 62.5 since grafted-HEMA gave the hydrophilicity to the rubber. As a result, the grafted-HEMA rubber realized 95% and higher wiping performance of water on glass.

Journal Articles

Structure and dynamics of poly(vinyl alcohol) gels in mixtures of dimethyl sulfoxide and water

Kanaya, Toshiji*; Takahashi, Nobuaki; Takeshita, Hiroki*; Okura, Masatoshi*; Nishida, Koji*; Kaji, Keisuke*

Polymer Journal, 44(1), p.83 - 94, 2012/01

 Times Cited Count:22 Percentile:62.08(Polymer Science)

Journal Articles

Thermoresponsive extraction of cadmium(II) ions by poly(TPEN-NIPA) gels; Effect of chain length and branched spacer structure on gel formation and extraction behavior

Inaba, Yusuke*; Tsumagari, Takayuki*; Kida, Tatsuya*; Watanabe, Wataru*; Nakajima, Yasutaka*; Fukuoka, Sachio*; Mori, Atsunori*; Matsumura, Tatsuro; Nakano, Yoshio*; Takeshita, Kenji*

Polymer Journal, 43(7), p.630 - 634, 2011/07

 Times Cited Count:11 Percentile:38.19(Polymer Science)

${it N,N,N',N'}$-(tetrakis-2-pyridylmethyl)ethylenediamine (TPEN) derivatives bearing a polymerizable double bond in the substituent structure of the pyridine ring are synthesized and subjected to copolymerization with ${it N}$-isopropylacrylamide in the presence of AIBN. The obtained poly(TPEN-NIPA) gels show thermo-responsive swelling/shrinking behaviors and are employed for the extraction of cadmium(II) ion from the aqueous solution to examine the relationship of the gel characteristics and the extraction performance. The polymer gels composed of the TPEN derivative bearing C3, C4, C10 and branched C3 spacer chains are synthesized and temperature-dependent extraction behavior of cadmium ion is compared. These gels extract Cd(II) ion efficiently from the aqueous solution in the swelling state at 5$$^{circ}$$C, while little extraction is observed at 45$$^{circ}$$C with shrinking. It is found that poly(TPEN-NIPA) gel of branched C3 spacer (C3b) shows the excellent thermoresponsive extraction performance.

Journal Articles

The Static structure of polyrotaxane in solution investigated by contrast variation small-angle neutron scattering

Endo, Hitoshi; Mayumi, Koichi*; Osaka, Noboru*; Ito, Kozo*; Shibayama, Mitsuhiro*

Polymer Journal, 43(2), p.155 - 163, 2011/02

 Times Cited Count:7 Percentile:25.86(Polymer Science)

Polyrotaxane (PR) possesses a supramolecular structure in which cyclic molecules are threaded into an axial polymer. In this study, the static structure of PR dissolved in a good solvent was investigated using contrast variation small-angle neutron scattering. The conformation of the axial linear polymer and the alignment of cyclic molecules within the axial polymer were evaluated quantitatively with the help of a detailed derivation of scattering theory. The decomposed partial scattering functions of the cyclic molecules and the axial polymer and the cross-correlation between cyclic molecules and an axial polymer strongly supported the idea that the alignment of cyclic molecules threaded on the axial polymer is random. On the basis of experimental observation, the entropic origin of the stiffening of PR due to the array of cyclic molecules is discussed.

Journal Articles

Preirradiation graft polymerization of styrene in a poly(tetrafluoroethylene) film investigated by time-resolved small-angle neutron scattering

Iwase, Hiroki*; Sawada, Shinichi; Yamaki, Tetsuya; Maekawa, Yasunari; Koizumi, Satoshi

International Journal of Polymer Science, 2011(2011), p.301807_1 - 301807_7, 2011/00

 Times Cited Count:9 Percentile:32.49(Polymer Science)

Preirradiation graft polymerization of styrene in a poly(tetrafluoroethylene) (PTFE) film was examined by time-resolved small-angle neutron scattering (SANS). A crosslinked PTFE film, thickness of which is about 50$$mu$$m, was irradiated by $$gamma$$-ray and immersed in a mixed solvent of styrene monomer and toluene. SANS elucidated that graft polymerization proceeds by two reaction processes (I) and (II). In process (I) at 0$$<t<$$200 min, graft polymerization occurs at an interface between crystalline and amorphous PTFE domains and the grafted polystyrene segregates from PTFE, forming a thin layer with a sharp interface. In process (II) at 200$$<t<$$600 min, grafted PS layer starts to bridge between crystalline domains. At the end of process (II), 40% of total crystalline PTFE domain is covered by the grafted PS chains.

Journal Articles

Micro-fabrication of biodegradable polymers using focused ion beam

Okubo, Satoshi*; Takahashi, Tomohiro*; Takasawa, Yuya*; Gowa, Tomoko*; Sasaki, Takashi*; Nagasawa, Naotsugu; Tamada, Masao; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*

Journal of Photopolymer Science and Technology, 23(3), p.393 - 397, 2010/11

 Times Cited Count:4 Percentile:14.95(Polymer Science)

Microfabrication of biodegradable polymers such as poly(butylene succinate-${it co}$-adipate) (PBSA) and poly($$varepsilon$$-caprolactone) (PCL) were demonstrated using focused ion beam (FIB) with maskless direct etching. As the result, the micro structures of PBSA and PCL were obtained. The etching depth of both PBSA and PCL were increased with increasing FIB fluence, and the etching rates were estimated to be about 1.3 $$times$$ 10$$^{-18}$$ $$mu$$m/(ions cm$$^{-2}$$) and 1.2 $$times$$ 10$$^{-18}$$ $$mu$$m/(ions cm$$^{-2}$$), respectively. Moreover, very thin films of PBSA and PCL were made by spin-coating method. The thicknesses of the spin-coated samples were about 200 nm, and the surface roughness was less than 10 nm (RMS). The fine structures such as micro-gear of PBSA and PCL were obtained without solid debris. The line width of the fabricated structure was about 250 nm.

Journal Articles

High-rate crystallization of polycarbonate in spincast thin film

Ata, Seisuke*; Oka, Toshitaka; He, C.-Q.*; Odaira, Toshiyuki*; Suzuki, Ryoichi*; Ito, Kenji*; Kobayashi, Yoshinori*; Ougizawa, Toshiaki*

Journal of Polymer Science, Part B; Polymer Physics, 48(20), p.2148 - 2153, 2010/10

 Times Cited Count:4 Percentile:14.95(Polymer Science)

Surface morphology of bisphenol-A polycarbonate (BAPC) thin films with thickness ranging from 30 to 1000 nm on silicon substrates was studied by atomic force microscopy (AFM). The films were prepared by spincasting from 1,2-dichloroethane solutions of 0.25-5.0 wt % BAPC. Even though longer annealing than 250 h was necessary for complete crystallization for bulk BAPC, high crystallinity was observed for 30 nm thick film after annealing at 200 $$^{circ}$$C for 48 h in vacuum. Positron annihilation lifetime spectroscopy (PALS) measurements showed that the free volume hole size in 30 nm thick film was larger than that of bulk at 200 $$^{circ}$$C. Comparison of the BAPC concentration in the precursor solution with the overlap concentration suggests that the high crystallinity of the 30 nm BAPC film is due to less entangled chains caused by rapid removal of the solvent from the dilute solution.

Journal Articles

Surface modification of vulcanized rubber by radiation grafting, 1; Improvement in friction behavior

Mizote, Norihito*; Katakai, Akio; Tamada, Masao; Matsuoka, Hiroshige*

Journal of Applied Polymer Science, 117(5), p.2825 - 2830, 2010/09

Hydrophilic monomer, 2-hydroxyethyl methacrylate (HEMA), and hydrophobic monomer, 3-(methacryloyloxy)propyltris(trimethylsiloxy)silane (MPTS), were grafted on vulcanized rubber surface by simultaneous electron beam irradiation. We studied the characteristics of graft polymerization, the relationship between the contact angle of water on the modified surface and friction behavior at the moment of semi-dry. Grafted rubbers were investigated with composition ratio and contact angle. As a result of graft polymerization of HEMA and MPTS, the composition ratio increased as the monomer concentration and the irradiation dose increased. By the graft polymerization of HEMA, the contact angle decreased to approximately 70$$^{circ}$$. By the graft polymerization of MPTS, the contact angle increased approximately to 108$$^{circ}$$. Friction behavior at the moment of semi-dry was evaluated by $$Delta$$$$mu$$ which is difference with the coefficient of dry friction and maximum friction. The increase in the contact angle owing to hydrophobic properties by graft polymerization of MPTS led to the decrease of $$Delta$$$$mu$$. The decrease in the contact angle owing to hydrophilic properties by graft polymerization of HEMA resulted in the increase of $$Delta$$$$mu$$.

Journal Articles

Ion beam irradiation effects on resist materials

Gowa, Tomoko*; Takahashi, Tomohiro*; Oka, Toshitaka; Murakami, Takeshi*; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*

Journal of Photopolymer Science and Technology, 23(3), p.399 - 404, 2010/08

Journal Articles

Electron-beam-induced chromism combined with photo- or thermal reverse reaction for color imaging

Enomoto, Kazuyuki; Maekawa, Yasunari; Kono, Sachiko*; Iwasaki, Masakazu*; Narita, Tadashi*

Journal of Photopolymer Science and Technology, 23(2), p.217 - 224, 2010/06

 Times Cited Count:0 Percentile:0.01(Polymer Science)

Reversible color imaging on polymer films with spiropyran (SP-NO$$_{2}$$) or diarylethene (DE) has been examined by electron-beam (EB) induced chromism combined with a photo- or thermal reverse reaction. Colorless SP-NO$$_{2}$$ in a film transformed into red-colored merocyanine (MC-NO$$_{2}$$), which subsequently converted to the original SP-NO$$_{2}$$ via thermal treatment. In contrast, a photo reverse reaction could be applied for EB-induced color imaging using DE in the polymer films, where the thermally stable colored close-form can be converted to the original colorless open-form via photoreaction. The color images of 200 nm L/S patterns were produced in the PMMA film containing SP-NO$$_{2}$$; the images could be faded upon the thermal treatment. It is noted that these reactions are the first example for reversible transformation of color imaging induced by EB radiation together with heat or light treatment.

Journal Articles

Control of radial size of crosslinked polymer nanowire by ion beam and $$gamma$$ ray irradiation

Tsukuda, Satoshi*; Asano, Atsushi*; Sugimoto, Masaki; Idesaki, Akira; Seki, Shu*; Tanaka, Shunichiro*

Journal of Photopolymer Science and Technology, 23(2), p.231 - 234, 2010/06

 Times Cited Count:0 Percentile:0.01(Polymer Science)

The nanowires based on polystyrene (PS) and polycarbosilane (PCS) were formed by 450 MeV Xe beam irradiation to their thin films. The nanowires, which formed by crosslinking reaction along the single ion path, can isolated by development procedures. This technique is sometimes called as single particle nanofabrication technique (SPNT). In this paper, tow step irradiation of ion beam and ray was carried out in order to control their radial sizes. The radial sizes of nanowires, based on PS and PCS were increased with the dose of ray. The change of radial sizes, which depended on the dose, was quantitatively measured, and we discussed in terms of radiation induced gel formation.

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