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  2. Fujita Masahiro

Fujita Masahiro

  (藤田 正博)

Profile Information

Affiliation
Professor, Faculty of Science and Technology, Department of Materials and Life Sciences, Sophia University
Degree
博士（工学）(Mar, 2002, 東京農工大学)
Contact information
masahi-fsophia.ac.jp
Other name(s) (e.g. nickname)
Yoshizawa
Researcher number
50433793
J-GLOBAL ID
200901014332520864
researchmap Member ID
6000003382

(Subject of research)
Developement of fast proton conductive plastic crystals

Research Interests

 7

Research Areas

 1

Awards

 4

Papers

 191
  • Yoshizawa, M., Ohno, H.
    Electrochemical Aspects of Ionic Liquids, 2005  
  • Yoshizawa, M., Narita, A., Ohno, H.
    Electrochemical Aspects of Ionic Liquids, 2005  
  • Ohno, H., Yoshizawa, M.
    ACS Symposium Series, 902, 2005  
  • Yoshizawa, M., Ohno, H.
    Electrochemical Aspects of Ionic Liquids, 2005  
  • Yoshizawa, M., Ohno, H.
    Electrochemical Aspects of Ionic Liquids, 2005  
  • Ogihara, W., Yoshizawa, M., Ohno, H.
    Electrochemical Aspects of Ionic Liquids, 2005  
  • Yoshizawa, M., Ohno, H., Ogihara, W.
    Electrochemical Aspects of Ionic Liquids, 2005  
  • T Mukai, M Yoshio, T Kato, M Yoshizawa, H Ohno
    CHEMICAL COMMUNICATIONS, (10) 1333-1335, 2005  
    Two types of thermotropic smectic phase and of anisotropic ion conduction were observed in an amphiphilic ionic liquid, N-ethyl-N'-dodecylimidazolium dodecyl sulfonate/lithium tetrafluoroborate mixture.
  • M Yoshizawa, H Ohno
    CHEMISTRY LETTERS, 33(12) 1594-1595, Dec, 2004  
    Aliphatic and alicyclic ammonium inner salts containing an ether bond were prepared as a new family of zwitterionic liquids. Ether bond is not only effective for lowering melting points of ammonium-type zwitterions but also interesting to realize unique solid-solid transition.
  • OGIHARA Wataru, Yoshizawa-FUJITA MASAHIRO, OHNO Hiroyuk
    Chemistry letters, 33(8) 1022-1023, Aug, 2004  
    Novel ionic liquids (ILs) composed of azole type cation and anion were prepared. Triazole and tetrazole were coupled with 1-ethyl-3-methylimidazolium hydroxide. Obtained tetrazole salt was liquid at room temperature showing only glass transition temperature at −89 °C. The ionic conductivity reached to 8.9 × 10−3 S cm−1 at room temperature reflecting low viscosity of 42.5 cP at 25 °C. This is the first report on the ILs based on only azole type ions.
  • Yoshizawa-FUJITA MASAHIRO, Ono Hiroyuki
    Chemical Communications, 16 1828-1829, Aug, 2004  
  • W Ogihara, JZ Sun, M Forsyth, DR MacFarlane, M Yoshizawa, H Ohno
    ELECTROCHIMICA ACTA, 49(11) 1797-1801, Apr, 2004  
    We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10(-4) to 10(-3) S cm(-1) at room temperature. Gelation was found to cause little change in the Li-7 diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids. (C) 2004 Elsevier Ltd. All rights reserved.
  • W Klinklai, S Kawahara, T Mizumo, M Yoshizawa, Y Isono, H Ohno
    SOLID STATE IONICS, 168(1-2) 131-136, Mar, 2004  
    The ionic conductivity of highly deproteinized liquid natural rubber having epoxy group (LEDPNR) mixed with alkali metal salts was investigated through impedance analysis to clarify the effect of proteins present in the rubber. The LEDPNR, thus used, was prepared from depolymerization of epoxidized natural rubber (ENR) latex, which was deproteinized by incubation of the latex with proteolytic enzyme and surfactant. The ionic conductivity of the resulting LEDPNR was dependent upon the alkali metal salts, where the ionic conductivity of LEDPNR/bis(trifluoromethane sulfonyl)imide (LiTFSI) was higher than that of LEDPNR/lithium perchlorate (LiClO4). The difference in the ionic conductivity was attributed to the solubility of the salts through both high-resolution solid-state C-13 nuclear magnetic resonance (NMR) spectroscopy and measurements of spin-lattice relaxation time. The ionic conductivity of LEDPNR/LiTFSI was also dependent upon concentration of LiTFSI and the conductivity reached the highest value at 20 wt.%, which was different from the monotonic increase in the ionic conductivity of liquid ENR prepared from untreated natural rubber latex. (C) 2004 Elsevier B.V. All rights reserved.
  • S Washiro, M Yoshizawa, H Nakajima, H Ohno
    POLYMER, 45(5) 1577-1582, Mar, 2004  
    Ionic liquid-type polymer brushes having different hydrocarbon (HC) chain lengths between polymerizable group and imidazolium ring were synthesized. When the carbon number of HC chain was 6, the ionic liquid-type polymer brush exhibited the highest ionic conductivity of 1.37 x 10(-4) S cm(-1) at 30 degreesC reflecting low T-g of -60 degreesC. Moreover, for the first time, we succeeded in obtaining transparent and flexible films without considerable decrease in the ionic conductivity as compared with that of corresponding monomers by using suitable cross-linkers. The most ion conductive (1.1 x 10(-4) S cm(-1) at 30 degreesC) film was obtained when tetra(ethylene glycol)diacrylate was used 0.5 mol% to ionic liquid monomer as the cross-linker. This film is one of excellent conductive films among single-ion conductive materials. (C) 2004 Elsevier Ltd. All rights reserved.
  • FUJITA MASAHIRO, Asako Narita, Hiroyuki Ohno
    Australian Journal of Chemistry, 57(2) 139-144, Feb, 2004  
  • M Yoshio, T Kato, T Mukai, M Yoshizawa, H Ohno
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 413 2235-2244, 2004  Peer-reviewed
    Anisotropic ion-conductive materials have been prepared by self-assembly of a conventional ionic liquid and a hydroxyl-terminated liquid crystal. These assemblies form phase-segregated layered structures on the nanometer scale. Anisotropic ionic conductivities along the direction parallel and perpendicular to the layer have been successfully measured for the sample forming oriented monodomains. The ionic conductivity parallel to the layer (sigma(i//)) is higher than that perpendicular to the layer (sigma(iperpendicular to)). The maximal anisotropy (sigma(i//)/sigma(iperpendicular to)) is 2.6 x 10(3) at 37degreesC in the smectic B phase.
  • Ohno Hiroyuki, Yoshizawa-FUJITA MASAHIRO, Ogihara Wataru
    Electrochimica Acta, 50(2-3) 255-261, 2004  
  • Yoshio Masafumi, Kato Takashi, Mukai Tomohiro, Yoshizawa-FUJITA MASAHIRO, Ohno Hiroyuki
    Molecular Crystals and Liquid Crystals, 413(1) 99-108, 2004  
  • M Yoshizawa, W Xu, CA Angell
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 125(50) 15411-15419, Dec, 2003  
    We describe the behavior of the conductivity, viscosity, and vapor pressure of various binary liquid systems in which proton transfer occurs between neat Bronsted acids and bases to form salts with melting points below ambient. Such liquids form an important subgroup of the ionic liquid (IL) class of reaction media and electrolytes on which so much attention is currently being focused. Such "protic ionic liquids" exhibit a wide range of thermal stabilities. We find a simple relation between the limit set by boiling, when the total vapor pressure reaches one atm, and the difference in pK(a) value for the acid and base determined in dilute aqueous solutions. For DeltapK(a) values above 10, the boiling point elevation becomes so high (>300 degreesC) that preemptive decomposition prevents its measurement. The completeness of proton transfer in such cases is suggested by the molten salt-like values of the Walden product, which is used to distinguish good from poor ionic liquids. For the good ionic liquids, the hydrogen bonding of acid molecules to the proton-transfer anion is strong enough that boiling points, but not melting points, may maximize at the hydrogen-bonded dianion composition. High boiling liquids of this type constitute an interesting class of high-temperature protonic acid that may have high-temperature fuel cell applications.
  • Klinklai, W., Kawahara, S., Mizumo, T., Yoshizawa, M., Sakdapipanich, J.T., Isono, Y., Ohno, H.
    European Polymer Journal, 39(8) 1707-1712, Aug, 2003  
  • A Hayashi, M Yoshizawa, CA Angell, F Mizuno, T Minami, M Tatsumisago
    ELECTROCHEMICAL AND SOLID STATE LETTERS, 6(8) E19-E22, Aug, 2003  
    As a further example of the extraordinary solvent powers of ambient temperature molten salts (ATMS or "ionic liquids'') we demonstrate that lithium thiophosphate glasses, well known for their unicationic conduction mechanism, and high ambient conductivity, dissolve in the ATMS ethylmethylimidazolium tetrafluoroborate up to 30 mol %. Remarkably, the conductivity of this solution is higher than that of a solution of the same lithium salt content made with the salt lithium TFSI [bis(trifluoromethanesulfonyl)imide] which bestows high conductivity on most other solvents. The glass-saturated melt has almost the same conductivity as the glass itself. However their glass temperatures differ by some 200 K so it is clear that the solution retains little if any of the decoupled Li+ conduction mechanism of the glass. It may nevertheless make a suitable electrolyte for lithium cells of a novel kind. Since the ionic liquids may be incorporated in polymer gel electrolytes without significant loss of conductivity, the present solutions may prove valuable for solid-state electrochemical device applications. (C) 2003 The Electrochemical Society.
  • Hiroyuki Ohno, FUJITA MASAHIRO, Wataru Ogihara
    Electrochimica Acta, 48(14-16) 2079-2083, Jun, 2003  
  • H Ohno, C Suzuki, K Fukumoto, M Yoshizawa, K Fujita
    CHEMISTRY LETTERS, 32(5) 450-451, May, 2003  
    Modification of cytochrome c (cyt.c) by poly(ethylene oxide) (PEO) chains enabled the protein soluble in 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquid without denaturation. However, as the solution was full of ions, suitable supporting electrolyte (KCl) was essential for the electron transfer reaction of cyt.c in the ionic liquid to attain adequate ion size for the active center.
  • Kishimoto, K., Yoshio, M., Mukai, T., Yoshizawa, M., Ohno, H., Kato, T.
    Journal of the American Chemical Society, 125(11) 3196-3197, Feb, 2003  
  • M Yoshizawa, T Mukai, T Ohtake, K Kanie, T Kato, H Ohno
    SOLID STATE IONICS, 154 779-787, Dec, 2002  
    A series of liquid crystalline molecules, alpha,omega-bis{4-[(4'-pentyloxy (or -octyloxy)-4-biphenylyl)-carbonyloxy]phenyl}oligo(oxyethylene)s, was synthesized to prepare oriented oligo(oxyethylene) chains. The complexes with LiCF3SO3 spontaneously formed a smectic phase. Since a rigid rod part cannot solubilize the inorganic salts, the oxyethylene moieties form the ion-conductive layers in the smectic phase. The anisotropic ionic conductivity was measured by an impedance analyzer with gold comb-shaped electrode deposited on a glass substrate between Au teeth. The ionic conductivity between the gold teeth increased to 10(-3) S cm(-1) at 142 degreesC, but it dropped considerably to 10(-4) S cm(-1) above that temperature. The temperature corresponded to the isotropization point of the complex. Homeotropic orientation of the liquid crystalline complex enables to make a successive ion-conducting pathway, which is effective to obtain higher ionic conductivity. The effect of the added salts on the ionic conductivity was also analyzed. Higher ionic conductivity was obtained when the liquid crystals were complexed with LiCF3SO3. There is a suitable ion size for prompt ion migration in the oriented polyether. (C) 2002 Elsevier Science B.V. All rights reserved.
  • Hiroyuki Ohno, FUJITA MASAHIRO
    Solid State Ionics, 154-155 303-309, Dec, 2002  
  • W Ogihara, M Yoshizawa, H Ohno
    CHEMISTRY LETTERS, 31(9) 880-881, Sep, 2002  
    Novel ionic liquids containing alkali metal ions as component were prepared by the neutralization of N-ethylimidazole with various kinds of hydrogen sulfates (MHSO4; M = Li, Na, or K). All salts were obtained as transparent viscous liquids at room temperature. These ionic liquids showed ionic conductivity higher than 10(-4) S cm(-1) at room temperature, reflecting low glass transition temperature of below -60degreesC. This is the first report on alkali metal salts which are inherently liquid state at room temperature.
  • Yoshizawa, M., Ogihara, W., Ohno, H.
    Polymers for Advanced Technologies, 13(8) 589-594, Aug, 2002  
  • K Hoshino, K Kanie, T Ohtake, T Mukai, M Yoshizawa, S Ujiie, H Ohno, T Kato
    MACROMOLECULAR CHEMISTRY AND PHYSICS, 203(10-11) 1547-1555, Jul, 2002  
    Full Paper: Liquid-crystalline compounds 1 and 3 having perfluoroalkyl-terminated mesogens at both ends of poly(ethylene oxide) chains have been prepared. These compounds show smectic A (S-A) and C phases over 100 degreesC. The 8(X) Iso (isotropic) transition temperatures are higher by about 10 degreesC than those of the corresponding alkyl-substituted compounds 2 and 4. The incorporation of lithium triflate into 1 resulting complexes. The conplexes of 1 and 3 containing 50 mol-% of lithium triflate exhibit columnar phases. The ionic conductivities of the homotropically aligned complexes based on 1 along the direction perpendicular to the molecular director of the S-A phases are higher than those of the corresponding compound of 2. The increase of the ionic conductivities as well as the stabilization of the smectic phases for these perfluoroalkyl-terminated compounds may be due to the formation of more stabilized layered structures through the intermolecular interactions among the persluoroalkyl moieties.
  • Masahiro Yoshizawa, Hiroyuki Ohno
    IONICS, 8(3-4) 267-271, May, 2002  
    Four kinds of triple ion-type imidazolium salts have been prepared. These salts consist of an imidazolium cation incrporating two sulfonate groups, which is anticipated to provide a single-ion conductive matrix. The melting point of some of these was over 200 degrees C, whereas both sodium salts having methyl group on the imidazolium ring showed only a glass transition temperature at around 20 degrees C. They showed the highest ionic conductivity among these triple ion-type imidazolium salts. Since these imidazolium ions are rather large, the predominant mobile species will be the small counter-cation. These salts certainly open up new possibilities for functional ionic liquids.
  • M Yoshio, T Mukai, K Kanie, M Yoshizawa, H Ohno, T Kato
    ADVANCED MATERIALS, 14(5) 351-354, Mar, 2002  
  • M Yoshio, T Mukai, K Kanie, M Yoshizawa, H Ohno, T Kato
    CHEMISTRY LETTERS, 31(3) 320-321, Mar, 2002  
    Amphiphilic ionic liquid derivatives form self-organized lamellar liquid crystals with room temperature ionic liquids. The ionic conductivities along the smectic layers have been obtained for the samples aligned in the cells with electrodes. The highest value is 4.3 x 10(-2) S cm(-1) at 139degreesC.
  • Ohno, H., Yoshizawa, M.
    Electrochemistry, 70(2), 2002  
  • M Yoshizawa, W Ogihara, H Ohno
    ELECTROCHEMICAL AND SOLID STATE LETTERS, 4(6) E25-E27, Jun, 2001  
    A series of new ionic liquids were prepared by neutralizing five different imidazole derivatives with two imide-type acids such as bis(trifluoromethanesulfonyl)imide and bis(perfluoroethylsulfonyl)imide, and their ionic conductivity and thermal properties were investigated. All the imidazolium salts synthesized are liquid at room temperature. The ionic liquid of the methylimidazolium bis(trifluoromethanesulfonyl)imide system has the best ionic conductivity, 7.23 x 10(-3) S cm(-1) at 25 degreesC, of the series of five imidazolium salts. (C) 2001 The Electrochemical Society.
  • M Yoshizawa, H Ohno
    ELECTROCHIMICA ACTA, 46(10-11) 1723-1728, Mar, 2001  
    Poly(ethylene oxide) (PEO) derivatives having both vinyl group and imidazolium salt structure on their ends were prepared and polymerized. Molten salt-type polymer brushes having different ethylene oxide (EO) unit number and different tethering structure were prepared to analyze the effect of flexible spacer. The ionic conductivity and DSC measurement of molten salt-type polymer brushes were carried out. When the counteranion species of the polymer was TFSI-, molten salt polymer (1) in spite of rubber-like properties showed high ionic conductivity (1.49 x 10(-4) S cm(-1) at 30 degreesC) corresponds to that of monomers reflecting low T-g (- 56 degreesC). The PEO-tethering of molten salt with polymer matrix was effective to suppress the drop of ionic conductivity after polymerization. Three kinds of imidazolium cations, such as n-ethylimidazolium, n-methylimidazolium or 1-benzyl-2-methylimidazolium, were selected, and corresponding monomers were synthesized. These were polymerized to analyze the effect of terminal cationic structure on the ionic conductivity. In spite of different imidazolium cation, the ionic conductivity and T-g of macromonomers and their polymers were equivalent. The ionic conductivity of molten-salt polymers increased with increasing EO or ethylene unit number. It is suggested that the distance between vinyl polymer and terminal imidazolium cation was important factor with respect to high ionic conductivity for molten salt-type polymer brushes. (C) 2001 Elsevier Science Ltd. All rights reserved.
  • T Ohtake, K Kanie, M Yoshizawa, T Mukai, K Ito-Akita, H Ohno, T Kato
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 364(1) 589-596, 2001  
    Liquid-crystalline dimeric molecules consisting of rigid mesogenic cores and flexible oxyethylene spacers have been prepared. The ethoxy carbonyl and alkoxy groups are attached to the ends of the mesogenic cores. These molecules have been complexed with lithium triflate, resulting in thermal stabilization of the mesophases. Ionic conductivities along the direction perpendicular to the molecular director of the smectic A phases have been measured for these complexes.
  • M Yoshizawa, M Hirao, K Ito-Akita, H Ohno
    JOURNAL OF MATERIALS CHEMISTRY, 11(4) 1057-1062, 2001  
    We synthesized a series of imidazolium cations containing covalently-bound anionic sites, such as sulfonate or sulfonamide groups. These zwitterionic imidazolium salts were found to form molten salts just like ordinary imidazolium salts. However, regardless of the high ion density, these ions cannot migrate along potential gradients induced in the bulk. This is a new and unique characteristic in molten salts. When other salts were added to this, the ions generated from the newly added salts were able to behave as carrier ions. The ionic conductivity of a pure molten salt was 10(-9) S cm(-1) at 25 degreesC, but jumped to 10(-5) S cm(-1) by adding an equimolar amount of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at 50 degreesC. The zwitterionic salt having a sulfonamide group instead of sulfonate had an ionic conductivity of 10(-4) S cm(-1) at 50 degreesC after adding an equimolar amount of LiTFSI. These zwitterionic imidazolium salts having vinyl groups were synthesized and polymerized. In spite of their rubber-like properties they showed excellent ionic conductivities of around 10(-5) S cm(-1) at 50 degreesC following the addition of an equimolar amount of LiTFSI to the imidazolium cation unit.
  • M Yoshizawa, E Marwanta, H Ohno
    POLYMER, 41(26) 9049-9053, Dec, 2000  
    Poly(ethylene oxide) (PEO) of molecular weight 1000 (PEO1000) containing lithium benzenesulfonate (LiBs) (PEO1000/LiBs), PEO derivatives having benzenesulfonate groups on both chain ends (PEO1000-(BSLi)(2)), or 1-ethyl-2,3-dimethylimidazolium bromide (ImB), were each blended with natural rubber (NR). The ionic conductivity was measured from AC impedance values. The ionic conductivity of the mixture of NR and PEO1000/LiBs (40 wt%) was about 10(-6) S cm(-1) at 50 degrees C; this mixture retained rubbery physical characteristics. At NR content of 10 wt%, the ionic conductivity of the mixture (NR/PEO1000/LiBs) was 2.7 x 10(-5) S cm(-1) at 50 degrees C, approximately 10 times higher than that of the bulk PEO/LiBs mixture. For mixtures of NR and PEO1000-(BSLi)(2), no improvement in ionic conductivity by mixing was found. The ionic conductivity of the mixture of NR and ImB was about 10 times higher than for the bulk of PEO1000-(BSLi)(2) at a NR content of 10 wt%. We propose that the ionic conductivity of the mixture increases when an ion conducting matrix containing simple salt is added. On the other hand, the DSC curve for NR/PEO derivatives showed two T(g)s based on the separate components, suggesting phase separation of the PEO derivative in the NR phase. (C) 2000 Elsevier Science Ltd. All rights reserved.
  • T Ohtake, Y Takamitsu, K Ito-Akita, K Kanie, M Yoshizawa, T Mukai, H Ohno, T Kato
    MACROMOLECULES, 33(21) 8109-8111, Oct, 2000  
  • M Yoshizawa, K Ito-Akita, H Ohno
    ELECTROCHIMICA ACTA, 45(10) 1617-1621, 2000  
    Poly(ethylene oxide) (PEO) derivatives having a positively-charged group on the chain end were prepared to analyze anion conduction mechanism in the polyether moiety. Effects of the terminal group structure and anion species on the anionic conductivity were analyzed. The anionic conductivity of PEO-onium salts was about 10(-4) S cm(-1) at room temperature, which was much higher than that for corresponding cation conductors. This difference should be based on much weaker interaction force of ether oxygens toward anions than that for cations. The ionic conductivity was evaluated under the same segmental motion by normalizing the different glass transition temperature (T-g). As a result, reduced ionic conductivity was nearly equal among all kinds of anion and cation conductive PEO oligomers having charged group on the chain end. The T-g was revealed to mainly govern the ionic conductivity of the matrix. Since the interaction between anion and ether oxygen was certainly detected but it was weak to suppress the elevation of T-g, lower T-g and corresponding high ionic conductivity were observed in these anion conductive polyethers. (C) 2000 Elsevier Science Ltd. All rights reserved.
  • M Yoshizawa, H Ohno
    CHEMISTRY LETTERS, 28(9) 889-890, Sep, 1999  
    Poly(ethylene oxide) (PEO) derivatives having both vinyl group and imidazolium salt structure on their ends were prepared and polymerized. When molten salt domain was provided by changing chloride anion with bis(trifluoromethanesulfonylimide) anion, excellent ionic conductivity (1.20 x 10(-4) Scm(-1) at 30 degrees C) was observed in spite of rubber-like properties.

Misc.

 64
  • 畠山歓, 藤田正博
    機能材料, 45(3) 56-64, Mar 7, 2025  InvitedLast authorCorresponding author
  • Takuto Ootahara, Kan Hatakeyama-Sato, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ChemRxiv, May 13, 2024  Last authorCorresponding author
    Ionic plastic crystals (IPCs), which are soft crystals with plasticity and ionic conductivity, are expected to be applied as solid electrolytes in battery applications. Further improvement of ionic conductivity is necessary for practical use as an electrolyte for energy storage devices. Materials Informatics (MI) is a method of incorporating information science in materials development. In this research, MI is being used to develop IPCs with high ionic conductivity. By using informatics science in addition to chemical knowledge, this research can be carried out efficiently and innovatively. The synthesis of eight new compounds resulted in six of them being solid at room temperature, while two of them were in a liquid state, namely ionic liquids. We evaluated the phase transition temperatures and ionic conductivity for each compound. Notably, N-ethyl-N-methylpyrrolidinium trifluoromethyltrifluoroborate ([C2mpyr][CF3BF3]) exhibited a high ionic conductivity of 1.75×10-4 S cm-1 at 25 oC, which is one of the highest values reported among IPCs to date. The combination of an experimental and MI based approach revealed an improved understanding of the relationship between ion size and ionic conductivity for a series of pyrrolidinium-based IPCs, and it is expected that further improvements to this approach will yield greater understanding of structure-property relationships.
  • Yutaro Hayashi, Mariya Usami, Elisabeth R. D. Ito, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ChemRxiv, Feb 14, 2024  Last authorCorresponding author
    Cellulose is attracting attention for the development of environmentally friendly, carbon-neutral, sustainable materials. Cellulose derivatives with cationic groups have the potential for applications in various fields, e.g., electrolytes. However, the current situation is marked by a low degree of cationic group incorporation and a need for more efficient synthesis methods. In this study, cationic cellulose was synthesized using an epoxy derivative, 2,3-epoxypropyltrimethylammonium chloride (EPTMAC), in an aqueous pyrrolidinium hydroxide solution. Since an aqueous pyrrolidinium hydroxide solution is a strong alkaline solution, the solution not only exhibits a high cellulose solubility at room temperature but also facilitates the reaction between cellulose and the epoxy derivative. We investigated the influence of reaction time, temperature, cellulose concentration, cationic reagent concentration, and the selection of a precipitation solvent for purification on the degree of substitution (DS) value of cationic cellulose. The structure of the obtained cationic cellulose was examined using 1H NMR, 1H-1H TOCSY, 1H-13C HSQC measurements, and Fourier-transform infrared spectroscopy (FT-IR). As a result of increasing cellulose and EPTMAC concentrations, the DS value increased, reaching a maximum value of 1.9. Solubility tests indicated that the cationic cellulose with chloride counter-anions exhibited notable solubility even in ethanol when the DS values were over 1.2. Cationic cellulose with bis(trifluoromethylsulfonyl)amide (TFSA) anion synthesized with a view to battery applications was insoluble in water and exhibited a film-forming property. Thus, the solubility of cationic cellulose could be controlled by varying the anionic species.
  • Arata Matsui, Deandra Ayu Putri, Morgan L. Thomas, Yuko Takeoka, Masahiro Rikukawa, Masahiro Yoshizawa-Fujita
    ChemRxiv, Jan 17, 2024  Last authorCorresponding author
    Cellulose is one of the main components of plant cell walls, abundant on earth, and is a non-edible material that can be acquired at a low cost. Furthermore, there has been increasing interest in its use in environmentally friendly, carbon-neutral, sustainable materials. It is expected that the applications of cellulose will expand with the development of a simple processing method. Previously, it was demonstrated that cellulose can be dissolved in a non-heated, short-duration process using an aqueous pyrrolidinium hydroxide solution. In this study, we dissolved cellulose in aqueous N-butyl-N-methylpyrrolidinium hydroxide solution ([C4mpyr][OH]/H2O) and investigated the cellulose regeneration process based on changes in solubility upon application of CO2 gas. We investigated the effect of transformation of the anion chemical structure on cellulose solubility by flowing CO2 gas into [C4mpyr][OH]/H2O and conducted pH, FT-IR, and 13C NMR measurements. We observed that the changes in anion structure allowed for the modulation of cellulose solubility in [C4mpyr][OH]/H2O, thus establishing a simple and safe cellulose regeneration process. This regeneration process was also applied to enable the production of cellulose hydrogels. The hydrogel formed using this approach was revealed to be of a higher mechanical strength than that of an analogous hydrogel produced using the same dissolution solvent with addition of a cross-linker. The ability to produce cellulose-based hydrogels of different mechanical properties is expected to expand the possible applications.
  • 藤田正博
    液晶, 27(4) 240-244, Oct, 2023  InvitedCorresponding author
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