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

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

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

https://doi.org/10.1021/acs.macromol.7b01052

We elucidated the spatial distribution of filler particles in cross-linked poly(styrene--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.

Aspect-ratio-dependent phase transitions and concentration fluctuations in aqueous colloidal dispersions of charged platelike particles

Yamaguchi, Daisuke; Miyamoto, Nobuyoshi*; Fujita, Takako*; Nakato, Teruyuki*; Koizumi, Satoshi; Ota, Noboru*; Yagi, Naoto*; Hashimoto, Takeji

Physical Review E, 85(1), p.011403_1 - 011403_15, 2012/01

https://doi.org/10.1103/PhysRevE.85.011403

Phase transition of aqueous colloidal dispersions of charged plate-like particles of niobate nanosheets were investigated as a function of the aspect ratio () and particle volume concentration () by small-angle neutron scattering and small-angle X-ray scattering. The results elucidated the following three pieces of evidence: (1) the macroscopic phase separation of the dispersions into an isotropic phase and a liquid crystalline phase (LC) under the condition of (a) varying at a constant = 0.01, and of (b) varying (0.01 0.025) at a constant = 2.510. (2) the -induced phase transition of the LC phase from a nematic phase to a highly periodic layered phase upon increasing r under the condition (a). (3) the LC phase having remarkable concentration fluctuations of the particles which are totally unexpected for the conventional lyotropic molecular LC but which are anticipated to be general for the plate-like colloidal particles.

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

https://doi.org/10.1021/ma101235j

Combined SANS, SEC, NMR, and UV-vis studies of simultaneous living anionic copolymerization process in a concentrated solution; Elucidation of building-up processes of molecules and their self-assemblies

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

Macromolecules, 43(6), p.2948 - 2959, 2010/04

https://doi.org/10.1021/ma902542e

Dynamic nuclear polarization study of UV-irradiated butanol for hyperpolarized liquid NMR

Kumada, Takayuki; Noda, Yohei; Hashimoto, Takeji; Koizumi, Satoshi

Journal of Magnetic Resonance, 201(2), p.115 - 120, 2009/12

https://doi.org/10.1016/j.jmr.2009.08.011

We have carried out a dynamic nuclear polarization (DNP) study of proton spins of UV-irradiated solid butanol containing phenol. By the aid of butyl free radicals produced by the photolysis, the butanol sample was dynamically polarized up to the polarization of 1.4% at 1.5 K and 1.2 T. Unlike persistent free radicals such as nitroxy and trityl free radicals commonly used for DNP, the butyl free radicals immediately decay by melting. We propose that free radicals produced by UV-photolysis are applicable to the DNP-enhanced hyperpolarized liquid-state NMR.

Small-angle neutron scattering study of dynamically polarized polyethylenes

Noda, Yohei; Kumada, Takayuki; Hashimoto, Takeji; Koizumi, Satoshi

Physica B; Condensed Matter, 404(17), p.2572 - 2574, 2009/09

https://doi.org/10.1016/j.physb.2009.06.028

We polarized hydrogen nuclear spins of polyethylene samples, doped with organic radical (TEMPO), by use of a dynamic nuclear polarization (DNP) technique, in which the sample was irradiated by microwave (94 GHz) at 3.3 Tesla and 1.4 K. For the samples under the DNP state, we conducted small-angle scattering experiments with polarized neutrons. For the sample with low crystallinity (polarization: 32%), the shift of the incoherent scattering level was observed. For the sample with high crystallinity (polarization: 23%), the enhancement of the coherent scattering due to the crystalline structure was observed.

A Combined method of small-angle neutron scattering and neutron radiography to visualize water in an operating fuel cell over a wide length scale from nano to millimeter

Iwase, Hiroki; Koizumi, Satoshi; Iikura, Hiroshi; Matsubayashi, Masahito; Yamaguchi, Daisuke; Maekawa, Yasunari; Hashimoto, Takeji

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.95 - 98, 2009/06

https://doi.org/10.1016/j.nima.2009.01.165

We constructed an in-situ and simultaneous observation method as a result of combination between ultra-small-angle neutron scattering and neutron imaging (radiography). With this novel technique, we are able to visualize water distribution or transportation, occurring from micro to macro length scales in a polymer electrolyte fuel cell (PEFC). At a sample position of SANS-J-II at JRR-3, we installed a neutron imaging camera in order to construct an in-situ and simultaneous observation method by USANS and neutron imaging with monochromatized cold neutrons. In addition, in order to selectively observe MEA in a running PEFC by using the in-situ and simultaneous observation method, we need to replace carbon separators which cause strong small-angle scattering as a noise. To reduce this strong background, we replaced the carbon separators with the aluminium ones. As a result, the background scattering was minimized (1/10) as compared to before.

Super ODS steels R&D for fuel cladding of next generation nuclear systems, 9; Damage structure evolution under electron-irradiation

Onuki, Somei*; Hashimoto, Naoyuki*; Ukai, Shigeharu*; Kimura, Akihiko*; Inoue, Masaki; Kaito, Takeji; Fujisawa, Toshiharu*; Okuda, Takanari*; Abe, Fujio*

Proceedings of 2009 International Congress on Advances in Nuclear Power Plants (ICAPP '09) (CD-ROM), p.9307_1 - 9307_4, 2009/05

The aim of this study is to survey microstructural properties and irradiation response of advanced high Cr and Al ODS steels. The effects of minor element addition and heat-treatment are also investigated. In these steels, black dots-like dislocation loops were formed around oxide particles during electron irradiation, and then the behavior depended on the type of additional elements, but the irradiation resistance was confirmed generally. The irradiation response was not sensitive as the heat-treatment, but the minor element addition (Zr and Hf) showed an intensive suppressing the loop growth. The results suggest that a large number of oxides enhanced the mutual recombination of the irradiation-induced point defects, especially at their surface.

Frustrating the lamellar ordering transition of polystyrene--polyisoprene with a C additive

Zhao, Y.; Hashimoto, Takeji; Douglas, J.*

Journal of Chemical Physics, 130(12), p.124901_1 - 124901_6, 2009/03

https://doi.org/10.1063/1.3089667

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

Franois, C.*; Yamaguchi, Daisuke; Hashimoto, Takeji

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

https://doi.org/10.1021/ma800102a

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.