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Journal Articles

Computer simulation of reaction-induced self-assembly of cellulose via enzymatic polymerization

Kawakatsu, Toshihiro; Tanaka, Hirokazu; Koizumi, Satoshi; Hashimoto, Takeji

Journal of Physics; Condensed Matter, 18(36), p.S2499 - S2512, 2006/09

 Times Cited Count:5 Percentile:28.12(Physics, Condensed Matter)

We present a comparison between results of computer simulation and neutron scattering/electron microscopy observation on reaction-induced self-assembly of cellulose molecules synthesized via ${it in vitro}$ polymerization at specific sites of enzymes in an aqueous reaction medium.

Oral presentation

In-situ and real-time ultra-small-angle neutron scattering observation for reversible addition-fragmentation chain transfer living radical polymerization

Motokawa, Ryuhei; Koizumi, Satoshi; Iida, You; Kawakatsu, Toshihiro; Hashimoto, Takeji

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

In-situ and real-time ultrasmall-angle neutron scattering observation for living radical polymerization of poly(methyl mathacrylate)-block-polystyrene

Motokawa, Ryuhei; Koizumi, Satoshi; Iida, You; Zhao, Y.; Kawakatsu, Toshihiro; Hashimoto, Takeji

no journal, , 

no abstracts in English

Oral presentation

In-situ ultra-small-angle neutron scattering observation for reversible addition-fragmentation chain transfer living radical polymerization

Motokawa, Ryuhei; Koizumi, Satoshi; Hashimoto, Takeji; Iida, You*; Kawakatsu, Toshihiro

no journal, , 

We constructed a focusing ultra-small-angle scattering spectrometer (SANS-J-II) at research reactor JRR-3, Tokai, Japan. Focusing ultra-small-angle neutron scattering (USANS) and conventional small-angle neutron scattering (SANS) can observe the length scale about 1000 nm - 100 nm and 100 nm - 1 nm, respectively. Focusing USANS, thus realized, plays an important role to investigate the time-evolution of hierarchically ordered structures in the living radical polymerization solution, preparing poly(methyl methacrylate)-block-polystyrene. In the reaction process to synthesize PS block chains from the end of PMMA block chain, we found the interplay between macro and microdomain structures as follows. As the polymerization proceeds, (1) first by polymerization-induced disorder-order transition, a lamellar microdomain appears and (2) second by order-order transitions, the morphologies of microdomains change to PMMA cylinder and successively to PMMA sphere.

Oral presentation

The Association structure of tapered block copolymer in the simultaneous living anionic polymerization

Zhao, Y.; Miyamoto, Nobuyoshi*; Koizumi, Satoshi; Hashimoto, Takeji; Iida, You*; Kawakatsu, Toshihiro

no journal, , 

The simultaneous living anionic polymerization of non-deuterated isoprene (I) and styrene (S) monomers, initiated by sec-butyllithium in deuterated benzene (B-d6) was investigated by a combination of time-resolved small-angle neutron scattering (SANS), gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-Vis) spectroscopy. In this study, we aim to reveal the change of the association formed by living polymer chain ends during the polymerization process and find that the association number changes from 4 to 2.

Oral presentation

Microstructures of membrane electrode assembly investigated by polarization analysis neutron small-angle scattering; Water distribution in ion cluster

Koizumi, Satoshi; Putra, A.; Noda, Yohei; Yamaguchi, Daisuke; Tokumasu, Takashi*; Kawakatsu, Toshihiro*

no journal, , 

In order to perform a multi-scale observation on a membrane-electrolyte assembly (MEA) of polymer electrolyte fuel cell (PEFC), small-angle neutron scattering (SANS) was recently reinforced by advanced neutron optics. A focusing ultra-small-angle scattering method was developed by using a neutron lens. By combining a double crystal (Bonse-Hart) method, we are able to reach to 10 micron meter length scale, which corresponds to the size of aggregation by carbon powders in an electrode layer. Polarization analysis enables us to selectively remove incoherent scattering from hydrogen atoms and to detect coherent scattering due to ion-cluster of polymer electrolyte (Nafion) and water distribution in it. In order to output structural information in real space, we examined our SANS results by comparing images in real space obtained by low vacuum SEM and multi-scale computer simulations.

Oral presentation

Microstructures of membrane electrode assembly investigated by polarization analysis neutron small-angle scattering; Water distribution in ion cluster

Koizumi, Satoshi; Kawakatsu, Toshihiro*; Tokumasu, Takashi*

no journal, , 

no abstracts in English

Oral presentation

Anisotropic shape and power law behavior of the scattering peak observed on the layered phase of colloidal platelike particles

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

no journal, , 

The line shape of the scattering peaks from the layered phase of colloidal plate-like particles, which consist of niobate single layer crystal (often referred as "nanosheet"), was intensively examined in this study and a distinct anisotropy was found for the power law behavior of the peak intensity with respect to the q$$_{z}$$ and q$$_{x}$$ directions. Namely, the power law exponent of the peak intensity for q$$_{x}$$-direction was nearly double of that for q$$_{z}$$-direction. This experimental piece of evidence was at least qualitatively in agreement with Caille s prediction. In this study, the Caille' s formula was numerically integrated and the two-dimensional calculated scattering pattern was obtained. The q-behavior of the calculated scattering pattern is naturally similar to those of theoretical analysis and obtained experimental data.

Oral presentation

Analysis of highly periodic scattering data from a colloidal dispersion of plate-like particles

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

no journal, , 

A highly periodic morphology of liquid crystalline (LC) phase formed in the aqueous colloidal dispersions of charged plate-like particles of niobate nanosheets was investigated by small-angle scattering method. The scattering profile was examined by line shape analysis and compared with calculation based on the Caille's formula. Qualitatively, an agreement between the experimental data and calculation (or theory) was obtained for the anisotropic decay of the peak intensity between the radial direction and that of perpendicular to the radial direction. Further quantitative comparison is under progress.

Oral presentation

Scattering analysis for highly oriented colloidal dispersion consisting of sheet-like inorganic particles

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

no journal, , 

Self-assembled structures of aqueous colloidal dispersions of niobate nanosheets having a uniform thickness of d = 1.6 nm and an average lateral dimension of L = 650 nm, hence an extremely large nominal aspect ratio (L/d) of $$sim$$400 were studied by micro-beam synchrotron small-angle X-ray scattering (SAXS). The results elucidated highly orientated, periodic layered liquid crystalline phase exhibiting a multiple-order scattering peaks. The line-profiles of the multiple-order peaks were analyzed in the directions both parallel and perpendicular to the one-dimensional stacks of the nanosheets for each order of the peaks. The results were compared with the formula based on harmonic approximation. An experimental problem associated with effects of orientation distributions of the stacks on the line profile analyses was quantitatively examined.

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