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Journal Articles

Interfacial cross-link inhomogeneity of a phenolic resin on a silica surface as revealed by X-ray and neutron reflection measurements

Izumi, Atsushi*; Shudo, Yasuyuki*; Shibayama, Mitsuhiro*; Yoshida, Tessei*; Miyata, Noboru*; Miyazaki, Tsukasa*; Aoki, Hiroyuki

Macromolecules, 53(10), p.4082 - 4089, 2020/05

 Times Cited Count:4 Percentile:62.52(Polymer Science)

Journal Articles

Diffusion behavior of methanol molecules confined in cross-linked phenolic resins studied using neutron scattering and molecular dynamics simulations

Shudo, Yasuyuki*; Izumi, Atsushi*; Hagita, Katsumi*; Yamada, Takeshi*; Shibata, Kaoru; Shibayama, Mitsuhiro*

Macromolecules, 51(16), p.6334 - 6343, 2018/08

 Times Cited Count:9 Percentile:49.31(Polymer Science)

Journal Articles

Structure analysis and derivation of deformed electron density distribution of polydiacetylene giant single crystal by the combination of X-ray and neutron diffraction data

Tashiro, Koji*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; Ohara, Takashi; Hanesaka, Makoto*; Yoshizawa, Yoshinori*; Yamamoto, Hiroko*; Niimura, Nobuo*; Tanaka, Ichiro*; Kurihara, Kazuo*; et al.

Macromolecules, 51(11), p.3911 - 3922, 2018/06

 Times Cited Count:2 Percentile:12.11(Polymer Science)

Journal Articles

Hierarchically self-organized dissipative structures of filler particles in poly(styrene-$$ran$$-butadiene) rubbers

Yamaguchi, Daisuke; Yuasa, Takeshi*; Sone, Takuo*; Tominaga, Tetsuo*; Noda, Yohei*; Koizumi, Satoshi*; Hashimoto, Takeji*

Macromolecules, 50(19), p.7739 - 7759, 2017/10

 Times Cited Count:7 Percentile:38.76(Polymer Science)

We elucidated the spatial distribution of filler particles in cross-linked poly(styrene-$$ran$$-butadiene) rubbers (SBR) developed under a typical fillers/rubbers compounding process as one of dissipative structures formed under a stress field imposed on the given system. The dispersion state of the fillers in SBR was clarified on the basis of hierarchical structures consisting of five structure levels. More specifically, it has the following characteristics depending on the specific interactions: Small, compact clusters build up compact mass-fractal structures, while large, loose clusters build up open mass-fractal structures.

Journal Articles

Photonic crystals fabricated by block copolymerization-induced microphase separation

Motokawa, Ryuhei; Taniguchi, Tatsuo*; Kumada, Takayuki; Iida, You*; Aoyagi, Shota*; Sasaki, Yusuke*; Kori, Michinari*; Kishikawa, Keiki*

Macromolecules, 49(16), p.6041 - 6049, 2016/08

 Times Cited Count:10 Percentile:42.76(Polymer Science)

Journal Articles

Dispersing zwitterions into comb polymers for nonviral transfection; Experiments and molecular simulation

Ghobadi, A. F.*; Letteri, R.*; Parelkar, S. S.*; Zhao, Y.; Chan-Seng, D.*; Emrick, T.*; Jayaraman, A.*

Biomacromolecules, 17(2), p.546 - 557, 2016/02

 Times Cited Count:10 Percentile:46.63(Biochemistry & Molecular Biology)

Journal Articles

Hierarchical structure-property relationships in graft-type fluorinated polymer electrolyte membranes using small- and ultrasmall-angle X-ray scattering analysis

Tran Duy, T.*; Sawada, Shinichi; Hasegawa, Shin; Yoshimura, Kimio; Oba, Yojiro*; Onuma, Masato*; Katsumura, Yosuke*; Maekawa, Yasunari

Macromolecules, 47(7), p.2373 - 2383, 2014/04

 Times Cited Count:19 Percentile:62.68(Polymer Science)

The hierarchical structures of graft-type ETFE-based polymer electrolyte membranes (ETFE-PEMs) were investigated using small- and ultrasmall-angle X-ray cattering experiments. The ETFE-PEMs with IECs $$<$$ 2.4 mmol/g possessed conducting graft domains around lamellar crystals, with a d-spacing of 21.8-29.1 nm, and oriented crystallites with short and long correlation distances of 218-320 and 903-1124 nm, respectively. The membranes with IECs $$>$$ 2.7 mmol/g showed a new phase of crystallite network domains with a d-range of 225-256 nm, indicating a phase transition from oriented crystallite to crystallite network structures in the IEC range of 2.4-2.7 mmol/g. Noted that for the ETFE-PEMs with high IECs higher conductivity at 30% RH and compatible tensile strengths at 100% RH and 80 $$^{circ}$$ C, compared with Nafion, originated from the well-interconnected ion channels around the crystallites and the remaining lamellar crystals and crystallites, respectively.

Journal Articles

Order-disorder transition of nanocomposites; Polystyrene-$$block$$-poly(methyl methacrylate) with Pd nanoparticles

Zhao, Y.; Saijo, Kenji*; Hashimoto, Takeji

Macromolecules, 46(3), p.957 - 970, 2013/02

 Times Cited Count:7 Percentile:26.96(Polymer Science)

Journal Articles

Small-angle neutron scattering study on specific polymerization loci induced by a copolymerization of polymerizable surfactant and styrene during miniemulsion polymerization

Motokawa, Ryuhei; Taniguchi, Tatsuo*; Sasaki, Yusuke*; Enomoto, Yuto*; Murakami, Fumiyasu*; Kasuya, Masakatsu*; Kori, Michinari*; Nakahira, Takayuki*

Macromolecules, 45(23), p.9435 - 9444, 2012/11

 Times Cited Count:6 Percentile:23.58(Polymer Science)

Journal Articles

Hierarchical structure analysis of graft-type polymer electrolyte membranes consisting of cross-linked polytetrafluoroethylene by small-angle scattering in a wide-$$Q$$ range

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

Macromolecules, 45(22), p.9121 - 9127, 2012/11

 Times Cited Count:17 Percentile:56.02(Polymer Science)

Fundamental understanding of the structure-property relationship of polymer electrolyte membranes (PEM) is prerequisite for a material design satisfying PEM performance requirement. Small-angle scattering in a wide-$$Q$$ range was observed by focusing small-angle neutron scattering (FSANS), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). The hierarchical structure of the PEM was characterized as being composed of conducting layers (graft domains) in lamellar stacks with 48-57 nm spacing on the surfaces of 480 nm diameter crystallites and ultra-small structures with a 1.7 nm correlation distance of the sulfonic acid groups in the conducting layers. From the change in the SAXS profiles as a function of grafting degrees, it was revealed that the graft domains around the crystallites were connected with the adjoining domains and thus, the PEMs with a higher degree of grafting had conductivity higher than that of Nafion.

Journal Articles

Crystal structure analysis of poly(L-lactic acid) $$alpha$$ form on the basis of the 2-dimensional wide-angle synchrotron X-ray and neutron diffraction measurements

Wasanasuk, K.*; Tashiro, Koji*; Hanesaka, Makoto*; Ohara, Takashi*; Kurihara, Kazuo; Kuroki, Ryota; Tamada, Taro; Ozeki, Tomoji*; Kanamoto, Tetsuo*

Macromolecules, 44(16), p.6441 - 6452, 2011/07

 Times Cited Count:137 Percentile:98.1(Polymer Science)

The crystal structure of poly(L-lactic acid) (PLLA) $${alpha}$$ form has been analyzed in detail by utilizing the 2-dimensional wideangle X-ray (WAXD) and neutron diffraction (WAND) data measured for the ultradrawn sample. The WAXD data were collected using a synchrotron-sourced high-energy X-ray beam of wavelength 0.328${AA}$ at SPring-8 and the WAND data were measured using a neutron beam of wavelength 1.510${AA}$ with a BIX-3 detector at JRR-3, JAEA. The initial crystal structure model was extracted successfully by a direct method under the assumption of the space group ${it P}$2$$_{1}$$2$$_{1}$$2$$_{1}$$ using about 700 X-ray reflections observed at -150$$^{circ}$$C. The crystal structure model obtained by the direct method was refined so that the best agreement between the observed and calculated integrated intensities was obtained or the reliability factor (${it R}$) became minimal: ${it R}$ was 18.2% at -150$$^{circ}$$C and 23.2% at 25$$^{circ}$$C. The obtained chain conformation took the distorted (10/3) helical form with 2$$_{1}$$ helical symmetry along the chain axis. However, the symmetrically forbidden reflections were detected in a series of the 00l reflections, requiring us to erase the 2$$_{1}$$ screw symmetry along the molecular chain. By assuming the space group symmetry ${it P}$2$$_{1}$$, the structural refinement was made furthermore and the finally obtained R factor was 19.3% at -150$$^{circ}$$C and 19.4% at 25$$^{circ}$$C. This refined model was found to reproduce the observed reflection profiles well for all the layer lines. The X-ray-analyzed crystal structure was transferred to the WAND data analysis to determine the hydrogen atomic positions. The ${it R}$ factor was 23.0% for the 92 observed reflections at 25$$^{circ}$$C. The agreement between the observed and calculated layer line profiles was good.

Journal Articles

In situ and time-resolved small-angle neutron scattering observation of star polymer formation via arm-linking reaction in ruthenium-catalyzed living radical polymerization

Terashima, Takaya*; Motokawa, Ryuhei; Koizumi, Satoshi*; Sawamoto, Mitsuo*; Kamigaito, Masami*; Ando, Tsuyoshi*; Hashimoto, Takeji*

Macromolecules, 43(19), p.8218 - 8232, 2010/10

 Times Cited Count:37 Percentile:77.54(Polymer Science)

Journal Articles

Soap-free emulsion polymerization of poly(ethylene glycol)-${it block}$-poly($$N$$-isopropylacrylamide); Elucidation of specific reaction fields for quasi-living polymerization by time-resolved SANS

Motokawa, Ryuhei; Koizumi, Satoshi*; Hashimoto, Takeji*; Annaka, Masahiko*; Nakahira, Takayuki*

Macromolecules, 43(2), p.752 - 764, 2010/01

 Times Cited Count:15 Percentile:48.02(Polymer Science)

Journal Articles

Combined SANS, SEC, NMR, and UV-Vis studies of simultaneous living anionic copolymerization process; Simultaneous elucidation of propagating living chains at three different length scales

Zhao, Y.; Tanaka, Hirokazu*; Miyamoto, Nobuyoshi*; Koizumi, Satoshi; Hashimoto, Takeji

Macromolecules, 42(5), p.1739 - 1748, 2009/04

 Times Cited Count:13 Percentile:44.13(Polymer Science)

Journal Articles

SAXS analysis of the order-disorder transition and the interaction parameter of polystyrene-${it block}$-poly(methyl methacrylate)

Zhao, Y.; Sivaniah, E.*; Hashimoto, Takeji

Macromolecules, 41(24), p.9948 - 9951, 2008/12

 Times Cited Count:109 Percentile:95.67(Polymer Science)

Journal Articles

Theoretical modeling of associated structures in aqueous solutions of hydrophobically modified telechelic PNIPAM based on a neutron scattering study

Koga, Tsuyoshi*; Tanaka, Fumihiko*; Motokawa, Ryuhei; Koizumi, Satoshi; Winnik, F. M.*

Macromolecules, 41(23), p.9413 - 9422, 2008/11

 Times Cited Count:68 Percentile:89.91(Polymer Science)

On the basis of results from a small-angle neutron scattering (SANS) study of aqueous solutions of a telechelic PNIPAM with octadecyl end groups, we developed a theoretical model of the self-assembly of this polymer in water as a function of temperature and concentration. This model leads us to the following description. In solutions of concentration 10 gL$$^{-1}$$ kept between 10 and 20$$^{circ}$$C, telechelic PNIPAMs (${it M}$$ $_{n}$$) 22 200 gmol$$^{-1}$$) associate in the form of flower micelles, containing about 12 polymer chains, assembled in a three-layered core-shell morphology with an inner core consisting of the octadecyl units, a dense inner shell consisting of partly collapsed PNIPAM chains, and an outer shell of swollen hydrated chains. Drastic changes in the scattering profile of the solution heated above 31$$^{circ}$$C are attributed to the formation of mesoglobules (diameter of 40 nm) consisting of about 1000 polymer chains. On further heating, the aggregation number of the mesoglobules increases. It reaches a value of 9000 at 34$$^{circ}$$C and stays constant upon further heating. In solutions of lower concentration (1 gL$$^{-1}$$), association of flower micelles and mesoglobules does not occur; however, the structure of individual flower micelles and mesoglobules is not affected by the change in concentration. In solutions of 50 gL$$^{-1}$$ in which flower micelles are expected to be partially connected by bridge chains, a peak attributed to correlation between flower micelles appears in the scattering profiles recorded at low temperature (10-20$$^{circ}$$C). In spite of the intermicellar bridging connection, the overall temperature dependence of the scattering profile at 50 gL$$^{-1}$$ remains similar to that at 10 gL$$^{-1}$$. Distinct features of the self-assembled structures formed in aqueous telechelic PNIPAM solutions are discussed in terms of the interactions between water and the polymer main chains.

Journal Articles

Morphological and scattering studies of binary mixtures of block copolymers; Cosurfactant effects observed in the parameter space of temperature, blend composition, and molecular weight ratio

Fran$c{c}$ois, C.*; Yamaguchi, Daisuke; Hashimoto, Takeji

Macromolecules, 41(13), p.4828 - 4837, 2008/07

 Times Cited Count:22 Percentile:59.12(Polymer Science)

Thermoreversible order-order transitions between various morphologies occurring on binary mixtures of diblock copolymers were investigated by using small-angle X-ray scattering. The complex morphological behaviors observed here can be understood on the basis of two key features of the binary blends: the co-surfactant effect and the possibility for the chemical junctions of the shorter diblock to migrate away from the interface as segregation power decreases. As a summary of this series of studies, a three-dimensional phase diagram was constructed in the parameter space of overall volume fraction of polystyrene block in the mixture, the ratio of the degree of polymerization of long asymmetric diblock chain to that of short symmetric diblock chain and temperature. Such a phase diagram illustrates that the cosurfactant effect opens perspectives in tailoring morphologies of self-assembled, nano-structured materials.

Journal Articles

Symmetric diblock copolymer thin films on rough substrates; Microdomain periodicity in pure and blended films

Sivaniah, E.*; Matsubara, Shinya*; Zhao, Y.; Hashimoto, Takeji; Fukunaga, Kenji*; Kramer, E. J.*; Mates, T. E.*

Macromolecules, 41(7), p.2584 - 2592, 2008/04

 Times Cited Count:33 Percentile:72.4(Polymer Science)

Journal Articles

Control of self-assembling processes of polyamidoamine dendrimers and Pd nanoparticles

Tanaka, Hirokazu*; Hashimoto, Takeji; Koizumi, Satoshi; Ito, Hideaki*; Naka, Kensuke*; Chujo, Yoshiki*

Macromolecules, 41(5), p.1815 - 1824, 2008/03

 Times Cited Count:7 Percentile:25.94(Polymer Science)

We have investigated the self-assembly formed by palladium acetate (Pd(OAc)$$_{2}$$) and polyamidoamine dendrimers (GN-NH$$_{2}$$) in a mixed solvent of methanol and N, N-dimethylformamide. We aim to explore effects of the generation number (GN) and concentration of the dendrimers, [GN-NH$$_{2}$$], on the self-assembly of the dendrimers (defined hereafter as "templates") and the Pd nanoparticles inside the templates in order to clarify physical factors controlling the self-assembling mechanisms. We found that the templates are formed only when [GN-NH$$_{2}$$] falls below a critical value and thereby a sufficient amount of Pd(OAc)$$_{2}$$ exists as the binders between the dendrimers. Otherwise dendrimers are molecularly dispersed in solution.

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