Nanocellulose hydrogels formed via crystalline transformation from cellulose I to II and subsequent freeze cross-linking reaction

Sekine, Yurina; Nankawa, Takuya; Hiroi, Kosuke; Oba, Yojiro*; Nagakawa, Yoshiyasu*; Sugita, Tsuyoshi; Shibayama, Yuki; Ikeda-Fukazawa, Tomoko*

Carbohydrate Polymers, 327, p.121538_1 - 121538_11, 2024/03

https://doi.org/10.1016/j.carbpol.2023.121538

We describe non-toxic, tough nanocellulose (NC) hydrogels formed from chemically unmodified NC by cellulose crystalline transformation and subsequent freeze cross-linking reaction. Using low-concentration NaOH and freezing together induced the crystalline transformation of NC from cellulose I to II via freeze concentration. After the crystalline transformation, cross-linking between the NC and CA in the freeze concentration layer (FCL) provided a strong NC network structure, forming NC hydrogels with high mechanical strength. The freeze-cross-linked NC hydrogel easily retained powder adsorbents in its inner space by mixing the NC-NaOH sol and the powder, and the hydrogel showed high removal efficiency for heavy metals. The results highlight the versatility of chemically unmodified celluloses in developing functional materials, suggest possible practical applications.

Effects of Fe ions, ultraviolet irradiation, and heating on microscopic structures of black lacquer films

Nankawa, Takuya; Sekine, Yurina; Matsumura, Daiju; Hiroi, Kosuke; Takata, Shinichi; Kamiya, Yoshimi*; Honda, Takayuki*

Langmuir, 40(11), p.5725 - 5730, 2024/03

https://doi.org/10.1021/acs.langmuir.3c03412

The chemical reaction between Fe and lacquer has been used to create the black color lacquer since ancient times. Here, the chemical state of Fe ions in black lacquer was investigated by using X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and Fourier transform-infrared (FT-IR) spectroscopy. Fe(II) or Fe(III) was added to the lacquer paste to prepare black lacquer films by air drying, heating, or UV irradiation. The XANES spectral features of all the film samples were similar, meaning that the Fe ions in the samples existed in the trivalent state regardless of the oxidation state of the initially added Fe. The corresponding Fourier transforms of the EXAFS spectra around the Fe K-edge were used to investigate Fe sites in the lacquer films. The spectra of all the film samples were similar shapes, but the peak intensities decreased in the order air dried heated UV irradiated films. This result indicates that heating and UV irradiation made the coordination structure of Fe in the lacquer non-uniform, and that heating caused the greatest non-uniformity. The complementary use of XANES, XAFS, and FT-IR spectroscopy is highly effective for non-destructive analysis of black lacquer in precious cultural artifacts.

Development of a DO/HO vapor generator for contrast-variation neutron scattering

Arima-Osonoi, Hiroshi*; Takata, Shinichi; Kasai, Satoshi*; Ouchi, Keiichi*; Morikawa, Toshiaki*; Miyata, Noboru*; Miyazaki, Tsukasa*; Aoki, Hiroyuki; Iwase, Hiroki*; Hiroi, Kosuke; et al.

Journal of Applied Crystallography, 56(6), p.1802 - 1812, 2023/12

https://doi.org/10.1107/S1600576723009780

Polarized neutrons observed nanometer-thick crystalline ice plates in frozen glucose solution

Kumada, Takayuki; Nakagawa, Hiroshi; Miura, Daisuke; Sekine, Yurina; Motokawa, Ryuhei; Hiroi, Kosuke; Inamura, Yasuhiro; Oku, Takayuki; Oishi, Kazuki*; Morikawa, Toshiaki*; et al.

Journal of Physical Chemistry Letters (Internet), 14(34), p.7638 - 7643, 2023/08

https://doi.org/10.1021/acs.jpclett.3c01448

The structure of nano-ice crystals in rapidly frozen glucose solution was elucidated by using spin-contrast-variation small-angle neutron scattering, which distinguishes the nano-ice crystal signal from the frozen amorphous solution signal by the polarization-dependent neutron scattering. The analysis revealed that the nano-ice crystals form a planar structure with a diameter exceeding tens of nanometers and a thickness of 1 nm, which is close to the critical nucleation size. This result suggests that the glucose molecules are preferentially bound to a specific face of nano-ice crystals, and then block the crystal growth perpendicular to that face.

Dynamic exchange of amphiphilic random copolymers between micelles in water; Kinetics and mechanism analyzed by TR-SANS

Hibino, Masayuki*; Takata, Shinichi; Hiroi, Kosuke; Aoki, Hiroyuki; Terashima, Takaya*

Macromolecules, 56(8), p.2955 - 2964, 2023/04

https://doi.org/10.1021/acs.macromol.2c02408

Sodium diffusion in hard carbon studied by small- and wide-angle neutron scattering and muon spin relaxation

Oishi, Kazuki*; Igarashi, Daisuke*; Tatara, Ryoichi*; Kawamura, Yukihiko*; Hiroi, Kosuke; Suzuki, Junichi*; Umegaki, Izumi*; Nishimura, Shoichiro*; Koda, Akihiro*; Komaba, Shinichi*; et al.

Journal of Physics; Conference Series, 2462, p.012048_1 - 012048_5, 2023/03

https://doi.org/10.1088/1742-6596/2462/1/012048

Microscopic structural changes during the freeze cross-linking reaction in carboxymethyl cellulose nanofiber hydrogels

Miura, Daisuke*; Sekine, Yurina; Nankawa, Takuya; Sugita, Tsuyoshi; Oba, Yojiro; Hiroi, Kosuke; Ozawa, Tatsuhiko

Carbohydrate Polymer Technologies and Applications (Internet), 4, p.100251_1 - 100251_9, 2022/12

https://doi.org/10.1016/j.carpta.2022.100251

The reaction mechanism of carboxymethyl cellulose nanofiber (CMCF) hydrogel formed by freeze-crosslinking was investigated. We succeeded in observing the hierarchical structural changes during the freeze-crosslinking reaction. Freeze-crosslinked CMCF hydrogels exhibited a characteristic hierarchical alignment structure from the angstrom to micrometer scale that differed from normal cross-linked CMCF hydrogels produced by a conventional method without freezing. It was shown that the characteristic hierarchical structure contributes the excellent mechanical properties of freeze-crosslinked CMCF hydrogels.

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

Miura, Daisuke*; Kumada, Takayuki; Sekine, Yurina; Oku, Takayuki; Takata, Shinichi; Hiroi, Kosuke; Iwata, Takahiro*

J-PARC 22-02; J-PARC MLF Annual Report 2021, p.6 - 7, 2022/03

https://mlfinfo.jp/_src/resource/PEPngy9XwF/MLF_AR2021.pdf

We carried out spin contrast variation neutron powder diffractometry of glutamic acid crystal. The diffraction peak intensities varied as a function of proton polarization. We extracted the structure factor of hydrogen atoms from the variation of peak intensities.

Spontaneous formations of nanoconfined water in ionic liquids by small-angle neutron scattering

Abe, Hiroshi*; Nemoto, Fumiya*; Hiroi, Kosuke; Oishi, Kazuki*; Takata, Shinichi

Journal of Molecular Liquids, 346, p.117035_1 - 117035_6, 2022/01

https://doi.org/10.1016/j.molliq.2021.117035

Polarization analysis for small-angle neutron scattering with a He spin filter at a pulsed neutron source

Okudaira, Takuya; Ueda, Yuki; Hiroi, Kosuke; Motokawa, Ryuhei; Inamura, Yasuhiro; Takata, Shinichi; Oku, Takayuki; Suzuki, Junichi*; Takahashi, Shingo*; Endo, Hitoshi*; et al.

Journal of Applied Crystallography, 54(2), p.548 - 556, 2021/04

https://doi.org/10.1107/S1600576721001643

Neutron polarization analysis (NPA) for small-angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a He spin filter as a spin analyzer for the scattered neutrons. The He spin filter covers a sufficient solid angle for performing SANS experiments, and the relaxation time of the He polarization is sufficient for continuous use over a few days, thus reaching the typical duration required for a complete set of SANS experiments. Although accurate evaluation of the incoherent neutron scattering, which is predominantly attributable to hydrogen atoms in samples, is practically difficult using calculations based on the sample elemental composition, the developed NPA approach with consideration of the influence of multiple neutron scattering enabled reliable decomposition of the SANS intensity distribution into the coherent and incoherent scattering components. To date, NPA has not been well established as a standard technique for SANS experiments at pulsed neutron sources. This work is anticipated to greatly contribute to the accurate determination of the coherent neutron scattering component for scatterers in various types of organic sample systems in SANS experiments at J-PARC.