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.

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.

Structural investigation of sulfonated polyphenylene ionomers for the design of better performing proton-conductive membranes

Shiino, Keisuke*; Otomo, Toshiya; Yamada, Takeshi*; Arima, Hiroshi*; Hiroi, Kosuke; Takata, Shinichi; Miyake, Jumpei*; Miyatake, Kenji*

ACS Applied Polymer Materials (Internet), 2(12), p.5558 - 5565, 2020/11

https://doi.org/10.1021/acsapm.0c00895

Preparation, characterization, and dilute solution properties of four-branched cage-shaped poly(ethylene oxide)

Noda, Takashi*; Doi, Yuya*; Ota, Yutaka*; Takata, Shinichi; Takano, Atsushi*; Matsushita, Yushu*

Journal of Polymer Science, 58(15), p.2098 - 2107, 2020/08

https://doi.org/10.1002/pol.20200286

Phase behavior and Li ion conductivity of styrene-ethylene oxide multiblock copolymer electrolytes

Sarapas, J. M.*; Saijo, Kenji*; Zhao, Y.; Takenaka, Mikihito*; Tew, G. N.*

Polymers for Advanced Technologies, 27(7), p.946 - 954, 2016/07

https://doi.org/10.1002/pat.3753

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

AA2015-0476.pdf:1.08MB

https://doi.org/10.1038/pj.2015.82

We performed molecular dynamics (MD) simulations of telomeric single-stranded DNA and POT1 for 100 ns. The distance between (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.

Dependence of structure of polymer side chain on water structure in hydrogels

Sekine, Yurina; Takagi, Hajime*; Sudo, Sayoko*; Kajiwara, Yutaro*; Fukazawa, Hiroshi; Fukazawa, Tomoko*

Polymer, 55(24), p.6320 - 6324, 2014/11

https://doi.org/10.1016/j.polymer.2014.10.011

To investigate the effects of structure of polymer side chains on structure of water in hydrogels, Raman spectra of polyacrylamide (PAA) and poly-,-dimethylacrylamide (PDMAA) hydrogels were measured. PAA and PDMAA have similar chemical structures, except for the side chain structure. The result shows that the frequency of the OH stretching mode for the PAA hydrogel decreases as the water content decreases, while that for the PDMAA hydrogel increases. We conclude that most of the bound water molecules in the PAA hydrogel form four strong hydrogen bonds with the hydrophilic groups in the side chain of PAA, whereas those in the PDMAA hydrogel form weak hydrogen bonds with surrounding water molecules. The water structure is an important factor governing the physical and chemical properties of gel materials.

Graft-type polymer electrolyte membranes for fuel cells prepared through radiation-induced graft polymerization into alicyclic polybenzimidazoles

Park, J.*; Takayama, Toshio*; Asano, Masaharu; Maekawa, Yasunari; Kudo, Kazuaki*; Takayama, Toshio*

Polymer, 54(17), p.4570 - 4577, 2013/08

https://doi.org/10.1016/j.polymer.2013.06.042

Graft-type sulfonated polybenzimidazole was prepared through radiation-induced graft polymerization of styrenes into an alicyclic polybenzimidazole film and subsequent sulfonation. The alicyclic polybenzimidazole, ChPBI, was prepared from -1,4-cyclohexanedicarboxylic acid and 3,3'-diaminobenzidine using typical polycondensation. Anisotropic domains with a size of several tens of micrometers were found in the ChPBI films casted from LiCl-containing ,-dimethylacetamide. Irradiation of the ChPBI membranes with a 220 kGy dose of -rays created radical species with mean lifetimes of two days. The treatment of this membrane with a 50/50 (v/v) mixture of 1-propanol and styrene produced polystyrene graft chains. Sulfonation of the resulting grafted membrane with ClSOHOH occurred selectively on the polystyrene grafts. The sulfonated films showed proton conductivity on the order of 10 to 10 S/cm with an ion exchange capacity between 2.1 and 2.9 mmol/g. SEM-EDX analysis of the membrane indicated the presence of macrophase separated domains up to 1 m in diameter. The proton conductivity of the membrane did not decrease for 600 h at 120C in liquid water.

Effects of crosslinker density on the polymer network structure in poly-,-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

https://doi.org/10.1002/polb.23305

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

https://doi.org/10.1002/app.37512

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 80C 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.