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In this paper, in situ surface-initiated atom-transfer radical polymerization (SI-ATRP) based on both an open and a coated system, without using volatile reagents, was developed to overcome the limited usage of ATRP due to the necessity of sealing. Nonvolatile ionic liquid (IL)-type components were used, specifically N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide as the polymerizable monomer and N,N-diethylmethyl(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)imide as the polymerization solvent. In the experiment, the reversible-deactivation radical polymerization characteristics are properly ensured in nonvolatile ATRP solution coated on silicon wafer as thin liquid film, to form concentrated polymer brushes (CPBs). The average molecular weight and molecular-weight distribution of the polymer produced in the liquid film and formed on silicon wafer were measured by gel permeation chromatography, which confirms that the polymerization reaction occurred as designed. Furthermore, it is clarified that the surface of the polymer brush synthesized in situ swollen by IL also exhibited low friction characteristics, comparable to that synthesized in a typical immersion process. This paper is the first to establish the effectiveness of in situ preparation for CPBs by using the coating technique.
Ryo Satoh; Saika Honma; Hiroyuki Arafune; Ryo Shomura; Toshio Kamijo; Takashi Morinaga; Takaya Sato. In Situ Surface-Initiated Atom-Transfer Radical Polymerization Utilizing the Nonvolatile Nature of Ionic Liquids: A First Attempt. Polymers 2020, 13, 61 .
AMA StyleRyo Satoh, Saika Honma, Hiroyuki Arafune, Ryo Shomura, Toshio Kamijo, Takashi Morinaga, Takaya Sato. In Situ Surface-Initiated Atom-Transfer Radical Polymerization Utilizing the Nonvolatile Nature of Ionic Liquids: A First Attempt. Polymers. 2020; 13 (1):61.
Chicago/Turabian StyleRyo Satoh; Saika Honma; Hiroyuki Arafune; Ryo Shomura; Toshio Kamijo; Takashi Morinaga; Takaya Sato. 2020. "In Situ Surface-Initiated Atom-Transfer Radical Polymerization Utilizing the Nonvolatile Nature of Ionic Liquids: A First Attempt." Polymers 13, no. 1: 61.
Phenylboronic acid-bearing polyamidoamine dendrimer (PBA-PAMAM)/poly(vinyl alcohol) (PVA) multilayer films were prepared through the layer-by-layer (LbL) deposition of PBA-PAMAM solution and PVA solution. PBA-PAMAM/PVA films were constructed successfully through the formation of boronate ester bonds between the boronic acid moiety in PBA and 1,3-diol units in PVA. When the (PBA-PAMAM/PVA)5 films were immersed in rose bengal (RB) solution, RB was adsorbed onto the LbL films. The amount of RB adsorbed was higher in the LbL films immersed in acidic solution than in basic solution. The release of RB from the LbL films was also promoted in the basic solution, while it was suppressed in the acidic solution. The boronic acid ester is oxidized to phenol by hydrogen peroxide (H2O2) and the carbon-boron bond is cleaved, so that the (PBA-PAMAM/PVA)5 films can be decomposed by immersion in H2O2 solution. Therefore, when RB-adsorbed (PBA-PAMAM/PVA)5 films were immersed in H2O2 solution, the release of RB was moderately promoted when the solution was weakly acidic.
Kentaro Yoshida; Akane Yamaguchi; Hiroki Midorikawa; Toshio Kamijo; Tetsuya Ono; Takenori Dairaku; Takaya Sato; Tsutomu Fujimura; Yoshitomo Kashiwagi; Katsuhiko Sato. Adsorption and Release of Rose Bengal on Layer-by-Layer Films of Poly(Vinyl Alcohol) and Poly(Amidoamine) Dendrimers Bearing 4-Carboxyphenylboronic Acid. Polymers 2020, 12, 1854 .
AMA StyleKentaro Yoshida, Akane Yamaguchi, Hiroki Midorikawa, Toshio Kamijo, Tetsuya Ono, Takenori Dairaku, Takaya Sato, Tsutomu Fujimura, Yoshitomo Kashiwagi, Katsuhiko Sato. Adsorption and Release of Rose Bengal on Layer-by-Layer Films of Poly(Vinyl Alcohol) and Poly(Amidoamine) Dendrimers Bearing 4-Carboxyphenylboronic Acid. Polymers. 2020; 12 (8):1854.
Chicago/Turabian StyleKentaro Yoshida; Akane Yamaguchi; Hiroki Midorikawa; Toshio Kamijo; Tetsuya Ono; Takenori Dairaku; Takaya Sato; Tsutomu Fujimura; Yoshitomo Kashiwagi; Katsuhiko Sato. 2020. "Adsorption and Release of Rose Bengal on Layer-by-Layer Films of Poly(Vinyl Alcohol) and Poly(Amidoamine) Dendrimers Bearing 4-Carboxyphenylboronic Acid." Polymers 12, no. 8: 1854.
Glucose-sensitive films were prepared through the layer-by-layer (LbL) deposition of hemin-modified poly(ethyleneimine) (H-PEI) solution and DNA solution (containing glucose oxidase (GOx)). H-PEI/DNA + GOx multilayer films were constructed using electrostatic interactions. The (H-PEI/DNA + GOx)5 film was then partially decomposed by hydrogen peroxide (H2O2). The mechanism for the decomposition of the LbL film was considered to involve more reactive oxygen species (ROS) that were formed by the reaction of hemin and H2O2, which then caused nonspecific DNA cleavage. In addition, GOx present in the LbL films reacts with glucose to generate hydrogen peroxide. Therefore, decomposition of the (H-PEI/DNA + GOx)5 film was observed when the thin film was immersed in a glucose solution. (H-PEI/DNA + GOx)5 films exposed to a glucose solution for periods of 24, 48 72, and 96 h indicated that the decomposition of the film increased with the time to 9.97%, 16.3%, 23.1%, and 30.5%, respectively. The rate of LbL film decomposition increased with the glucose concentration. At pH and ionic strengths close to physiological conditions, it was possible to slowly decompose the LbL film at low glucose concentrations of 1–10 mM.
Kentaro Yoshida; Yu Kashimura; Toshio Kamijo; Tetsuya Ono; Takenori Dairaku; Takaya Sato; Yoshitomo Kashiwagi; Katsuhiko Sato. Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase. Polymers 2020, 12, 319 .
AMA StyleKentaro Yoshida, Yu Kashimura, Toshio Kamijo, Tetsuya Ono, Takenori Dairaku, Takaya Sato, Yoshitomo Kashiwagi, Katsuhiko Sato. Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase. Polymers. 2020; 12 (2):319.
Chicago/Turabian StyleKentaro Yoshida; Yu Kashimura; Toshio Kamijo; Tetsuya Ono; Takenori Dairaku; Takaya Sato; Yoshitomo Kashiwagi; Katsuhiko Sato. 2020. "Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase." Polymers 12, no. 2: 319.
Glucose-sensitive films were prepared by the layer-by-layer (LbL) deposition of poly(ethyleneimine) (H-PEI) solution and DNA solution (containing glucose oxidase (GOx)). H-PEI/DNA+GOx multilayer films were constructed using electrostatic interactions. The (H-PEI/DNA+GOx)5 film was then partially decomposed by hydrogen peroxide (H2O2). The mechanism for the decomposition of the LbL film was considered to involve a more reactive oxygen species (ROS) that was formed by the reaction of hemin and H2O2, which then caused nonspecific DNA cleavage. GOx present in the LbL films reacts with glucose to generate hydrogen peroxide. Therefore, decomposition of the H-PEI/DNA+GOx)5 film was observed when the thin film was immersed in a glucose solution. A (H-PEI/DNA+GOx)5 film exposed to a glucose solution for periods of 24, 48 72, and 96 h indicated decomposition of the film increased with the time. The rate of LbL film decomposition increased with the glucose concentration. At pH and ionic strength close to physiological conditions, it was possible to slowly decompose the LbL film at a sub-millimolar glucose concentration.
Kentaro Yoshida; Yu Kashimura; Toshio Kamijo; Tetsuya Ono; Takenori Dairaku; Takaya Sato; Yoshitomo Kashiwagi; Katsuhiko Sato. Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase. 2019, 1 .
AMA StyleKentaro Yoshida, Yu Kashimura, Toshio Kamijo, Tetsuya Ono, Takenori Dairaku, Takaya Sato, Yoshitomo Kashiwagi, Katsuhiko Sato. Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase. . 2019; ():1.
Chicago/Turabian StyleKentaro Yoshida; Yu Kashimura; Toshio Kamijo; Tetsuya Ono; Takenori Dairaku; Takaya Sato; Yoshitomo Kashiwagi; Katsuhiko Sato. 2019. "Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase." , no. : 1.
Chiharu Tadokoro; Kosuke Sato; Takuo Nagamine; Ken Nakano; Shinya Sasaki; Takaya Sato; Keita Sakakibara; Yoshinobu Tsujii. Concentrated Polymer Brush as Reciprocating Seal Material for Low Leakage and Low Friction. Tribology Transactions 2019, 63, 20 -27.
AMA StyleChiharu Tadokoro, Kosuke Sato, Takuo Nagamine, Ken Nakano, Shinya Sasaki, Takaya Sato, Keita Sakakibara, Yoshinobu Tsujii. Concentrated Polymer Brush as Reciprocating Seal Material for Low Leakage and Low Friction. Tribology Transactions. 2019; 63 (1):20-27.
Chicago/Turabian StyleChiharu Tadokoro; Kosuke Sato; Takuo Nagamine; Ken Nakano; Shinya Sasaki; Takaya Sato; Keita Sakakibara; Yoshinobu Tsujii. 2019. "Concentrated Polymer Brush as Reciprocating Seal Material for Low Leakage and Low Friction." Tribology Transactions 63, no. 1: 20-27.
We have newly designed five kinds of polyvalent solute that have two to four quaternary ammonium functional groups in one cation. Their molecular structure is designed to be as compact as possible, with either two or three cationic groups on a linear molecular structure, or three or four cationic moieties on three strands in a star-shape. The prepared solutes have a bis(trifluoromethylsulfonyl)imide anion in common and a flexible molecular structure that can easily adsorb onto the electrode surface of an electric double layer capacitor (EDLC). Since a single polyvalent solute molecule can accumulate more electric charge by adsorption than can a monovalent solute, a high capacitance is possible even at a low solute concentration compared with conventional cells. We evaluated some electrochemical properties of these polyvalent solutes as an electrolyte and their EDLC performance, including initial capacitance, rate characteristics and cycle durability. All the polyvalent solutes had a potential window of 5 V or more, and in particular the divalent salt showed a capacitor performance equivalent to that of the monovalent salt even at half salt concentration in the electrolyte. On the other hand, the trivalent and tetravalent solutes had a lower charge utilization rate compared with a monovalent solute.
Yuki Maruyama; Shoko Marukane; Takashi Morinaga; Saika Honma; Toshio Kamijo; Ryo Shomura; Takaya Sato. New design of polyvalent ammonium salts for a high-capacity electric double layer capacitor. Journal of Power Sources 2018, 412, 18 -28.
AMA StyleYuki Maruyama, Shoko Marukane, Takashi Morinaga, Saika Honma, Toshio Kamijo, Ryo Shomura, Takaya Sato. New design of polyvalent ammonium salts for a high-capacity electric double layer capacitor. Journal of Power Sources. 2018; 412 ():18-28.
Chicago/Turabian StyleYuki Maruyama; Shoko Marukane; Takashi Morinaga; Saika Honma; Toshio Kamijo; Ryo Shomura; Takaya Sato. 2018. "New design of polyvalent ammonium salts for a high-capacity electric double layer capacitor." Journal of Power Sources 412, no. : 18-28.
N,N-diethyl-N-(2-methancryloylethy)-N-methylammonium bis(trifluoromethylsulfonyl) imide polymer (DEMM-TFSI) brush coated specimens (substrate: glasses) and a liquid ion type of polymer brush coating were investigated for their antifouling effect on biofilms. Biofilms were produced by two kinds of bacteria, E. coli and S. epidermidis. They were formed on specimens immersed into wells (of 12-well plates) that were filled with culture liquids and bacteria. The biofilm formation was observed. Also, brush coated specimens and glass substrates were investigated in the same way. DEMM polymer brush coated specimens formed more biofilm than PMMA (polymethyl methacrylate) polymer brush coated specimens and glass substrates. A greater amount of polarized components of biofilms was also observed for DEMM polymer brush coated specimens. The polar characteristics could be attributed to the attraction capability of bacteria and biofilms on DEMM polymer brush coated specimens. When considering the ease of removing biofilms by washing it with water, the ionic liquid type polymer brush (coated specimens) could be used for antifouling applications. If an initial antifouling application is needed, then the polar characteristics could be adjusted (design of the components and concentrations of ionic liquids, etc.) to solve the problem.
Hideyuki Kanematsu; Atsuya Oizumi; Takaya Sato; Toshio Kamijo; Saika Honma; Dana M. Barry; Nobumitsu Hirai; Akiko Ogawa; Takeshi Kogo; Daisuke Kuroda; Katsuhiko Sano; Katsuhiko Tsunashima; Seung-Hyo Lee; Myeong-Hoon Lee. Biofilm Formation of a Polymer Brush Coating with Ionic Liquids Compared to a Polymer Brush Coating with a Non-Ionic Liquid. Coatings 2018, 8, 398 .
AMA StyleHideyuki Kanematsu, Atsuya Oizumi, Takaya Sato, Toshio Kamijo, Saika Honma, Dana M. Barry, Nobumitsu Hirai, Akiko Ogawa, Takeshi Kogo, Daisuke Kuroda, Katsuhiko Sano, Katsuhiko Tsunashima, Seung-Hyo Lee, Myeong-Hoon Lee. Biofilm Formation of a Polymer Brush Coating with Ionic Liquids Compared to a Polymer Brush Coating with a Non-Ionic Liquid. Coatings. 2018; 8 (11):398.
Chicago/Turabian StyleHideyuki Kanematsu; Atsuya Oizumi; Takaya Sato; Toshio Kamijo; Saika Honma; Dana M. Barry; Nobumitsu Hirai; Akiko Ogawa; Takeshi Kogo; Daisuke Kuroda; Katsuhiko Sano; Katsuhiko Tsunashima; Seung-Hyo Lee; Myeong-Hoon Lee. 2018. "Biofilm Formation of a Polymer Brush Coating with Ionic Liquids Compared to a Polymer Brush Coating with a Non-Ionic Liquid." Coatings 8, no. 11: 398.
Since human body joints have a gel-like structure with low friction that persists for several decades, hydrogels have attracted much interest for developing low-friction materials. However, such advantages can hardly be realized in industrial usage because water in the gel evaporates easily and the gel deswells. The substitution of water with an ionic liquid (IL) is one of the effective ways to overcome this problem. In this study, we substituted water in a double network (DN) hydrogel with 3-ethyl-1-methyl-imidazolium ethylsulfate (EMI-EtSulf), a hydrophilic IL, via a simple solvent exchange method to obtain a DN ion gel. A compressive test and thermogravimetric analysis showed that the DN ion gel has a high compression fracture stress and improved thermal properties, with the difference in 10% loss of temperature being ΔT10 = 234 °C. A friction test conducted using a reciprocating tribometer showed that the friction of a glass ball/DN ion gel was relatively higher than that of a glass ball/DN hydrogel. Because the minimum coefficient of friction (COF) value increased after substitution, the increase in polymer adhesion caused by the electrostatic shielding of the surface moieties of glass and poly 2-acrylamidomethylpropanesulfonic acid (PAMPS) was considered the main contributor to the high friction. As the COF value decreased with increasing temperature, the DN ion gel can achieve low friction via the restriction of polymer adhesion at high temperatures, which is difficult in the DN hydrogel owing to drying.
Hiroyuki Arafune; Fumiya Muto; Toshio Kamijo; Saika Honma; Takashi Morinaga; Takaya Sato. Tribological Properties of Double-Network Gels Substituted by Ionic Liquids. Lubricants 2018, 6, 89 .
AMA StyleHiroyuki Arafune, Fumiya Muto, Toshio Kamijo, Saika Honma, Takashi Morinaga, Takaya Sato. Tribological Properties of Double-Network Gels Substituted by Ionic Liquids. Lubricants. 2018; 6 (4):89.
Chicago/Turabian StyleHiroyuki Arafune; Fumiya Muto; Toshio Kamijo; Saika Honma; Takashi Morinaga; Takaya Sato. 2018. "Tribological Properties of Double-Network Gels Substituted by Ionic Liquids." Lubricants 6, no. 4: 89.
Glutamate sensors were prepared using nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP)‐dependent glutamate dehydrogenase (GDH). Glutamate was determined from the anodic oxidation current of NADH and NADPH generated by the enzymatic reaction of GDH. These two types of GDH enzymes were deposited separately on carbon nanotube (CNT) and reduced graphene oxide (rGO)‐modified glassy carbon electrodes, in which CNT and rGO were used to improve the oxidation capacity of the electrodes. An anodic peak current in response to 1 mM glutamate of glutamate sensors comprising each of these four combinations were compared under the same conditions. The glutamate response was the highest when NAD‐dependent GDH was deposited on the rGO‐modified electrode.
Katsuhiko Sato; Toshio Kamijo; Shigehiro Takahashi; Takaya Sato. Comparison of NAD with NADP-dependent Glutamate Dehydrogenase, and CNT with rGO-modified Electrodes, for the Construction of Glutamate Sensors. Electroanalysis 2018, 30, 2237 -2240.
AMA StyleKatsuhiko Sato, Toshio Kamijo, Shigehiro Takahashi, Takaya Sato. Comparison of NAD with NADP-dependent Glutamate Dehydrogenase, and CNT with rGO-modified Electrodes, for the Construction of Glutamate Sensors. Electroanalysis. 2018; 30 (10):2237-2240.
Chicago/Turabian StyleKatsuhiko Sato; Toshio Kamijo; Shigehiro Takahashi; Takaya Sato. 2018. "Comparison of NAD with NADP-dependent Glutamate Dehydrogenase, and CNT with rGO-modified Electrodes, for the Construction of Glutamate Sensors." Electroanalysis 30, no. 10: 2237-2240.
A type of polymer brush, made from an ionic liquid, was prepared and used to investigate the behavior and tendency of biofilm formation. The polymer brush specimens were immersed into the wells of microtiter plates filled with culture liquids containing bacteria. Two different combinations of bacteria and liquid cultures were used for this experiment. One was LB liquid medium with E-coli and the other was Heart Infusion liquid medium with S.epidermidis. After the specimens were immersed for a certain amount of time, they were removed from the test wells and evaluated for biofilm formation. The evaluation methods used were Raman Spectroscopy and crystal violet staining. Polymer brush specimens generally showed biofilm formations for specimens tested in both bacterial cases. However, both of these biofilms could be removed, when the specimens were immersed in water for a couple of hours. Probably the use of special polymer brushes will be valuable in the future, for controlling biofilm and related contaminants on a variety of materials and components.
Hideyuki Kanematsu; Atsuya Oizumi; Takaya Sato; Toshio Kamijo; Saika Honma; Dana M. Barry; Nobumitsu Hirai; Akiko Ogawa; Takeshi Kogo; Daisuke Kuroda; Katsuhiko Tsunashima. Polymer Brush Made by Ionic Liquids and the Inhibition Effects for Biofilm Formation. ECS Transactions 2018, 85, 1089 -1095.
AMA StyleHideyuki Kanematsu, Atsuya Oizumi, Takaya Sato, Toshio Kamijo, Saika Honma, Dana M. Barry, Nobumitsu Hirai, Akiko Ogawa, Takeshi Kogo, Daisuke Kuroda, Katsuhiko Tsunashima. Polymer Brush Made by Ionic Liquids and the Inhibition Effects for Biofilm Formation. ECS Transactions. 2018; 85 (13):1089-1095.
Chicago/Turabian StyleHideyuki Kanematsu; Atsuya Oizumi; Takaya Sato; Toshio Kamijo; Saika Honma; Dana M. Barry; Nobumitsu Hirai; Akiko Ogawa; Takeshi Kogo; Daisuke Kuroda; Katsuhiko Tsunashima. 2018. "Polymer Brush Made by Ionic Liquids and the Inhibition Effects for Biofilm Formation." ECS Transactions 85, no. 13: 1089-1095.
Among the possible solutions for achieving low friction, polymer brushes that are grafted onto surfaces are good candidates. The tribological characterization of such layers becomes more difficult when the friction is lower: the signal-to-noise ratio of the friction force that is measured with conventional tribometers impedes the precise quantification. Therefore, we have applied a new technique that has been developed at the Laboratory of Tribology and System Dynamics (LTDS), called the ‘oscillating relaxation tribometer’. The advantage of this original technique is that it characterizes low friction with unequalled sensitivity. The lower the friction, the better the precision, and it permits obtaining the ‘friction law’ directly from robust and rapid experimental tests. In this study, the samples that have been used are the ionic liquid-type polymer brushes (ILPBs) with different thicknesses, which have been grafted onto silicon wafers and steel coupons. The counter-face is a mirror-polished steel ball. We show that (i) a thick ILPB layer on silicon is very resistant to high contact pressure, up to 555 MPa; (ii) the friction behavior that is obtained is close to that of a Newtonian viscous one, even under maximum normal loads; (iii) poorer results are obtained for the thinner sample; and (iv) the repetition, up to 5000 oscillations on the same surface, does not affect the friction damping of the contact, which demonstrates that this film provides a favorable resistance to friction under severe contact conditions. In addition, the feasibility of grafting onto steel surfaces is demonstrated. The results are then discussed, with respect to friction and dissipation.
Michel Belin; Hiroyuki Arafune; Toshio Kamijo; Joël Perret-Liaudet; Takashi Morinaga; Saika Honma; Takaya Sato. Low Friction, Lubricity, and Durability of Polymer Brush Coatings, Characterized Using the Relaxation Tribometer Technique †. Lubricants 2018, 6, 52 .
AMA StyleMichel Belin, Hiroyuki Arafune, Toshio Kamijo, Joël Perret-Liaudet, Takashi Morinaga, Saika Honma, Takaya Sato. Low Friction, Lubricity, and Durability of Polymer Brush Coatings, Characterized Using the Relaxation Tribometer Technique †. Lubricants. 2018; 6 (2):52.
Chicago/Turabian StyleMichel Belin; Hiroyuki Arafune; Toshio Kamijo; Joël Perret-Liaudet; Takashi Morinaga; Saika Honma; Takaya Sato. 2018. "Low Friction, Lubricity, and Durability of Polymer Brush Coatings, Characterized Using the Relaxation Tribometer Technique †." Lubricants 6, no. 2: 52.
Using ultra-small angle X-ray scattering (USAXS), we analyzed the higher-order structures of nanoparticles with a concentrated brush of an ionic liquid (IL)-type polymer (concentrated-polymer-brush-modified silica particle; PSiP) in an IL and the structure of the swollen shell layer of PSiP. Homogeneous mixtures of PSiP and IL were successfully prepared by the solvent-casting method involving the slow evaporation of a volatile solvent, which enabled a systematic study over an exceptionally wide range of compositions. Different diffraction patterns as a function of PSiP concentration were observed in the USAXS images of the mixtures. At suitably low PSiP concentrations, the USAXS intensity profile was analyzed using the Percus–Yevick model by matching the contrast between the shell layer and IL, and the swollen structure of the shell and “effective diameter” of the PSiP were evaluated. This result confirms that under sufficiently low pressures below and near the liquid/crystal-threshold concentration, the studied PSiP can be well described using the “hard sphere” model in colloidal science. Above the threshold concentration, the PSiP forms higher-order structures. The analysis of diffraction patterns revealed structural changes from disorder to random hexagonal-closed-packing and then face-centered-cubic as the PSiP concentration increased. These results are discussed in terms of thermodynamically stable “hard” and/or “semi-soft” colloidal crystals, wherein the swollen layer of the concentrated polymer brush and its structure play an important role.
Yohei Nakanishi; Ryohei Ishige; Hiroki Ogawa; Keita Sakakibara; Kohji Ohno; Takashi Morinaga; Takaya Sato; Toshiji Kanaya; Yoshinobu Tsujii. USAXS analysis of concentration-dependent self-assembling of polymer-brush-modified nanoparticles in ionic liquid: [I] concentrated-brush regime. The Journal of Chemical Physics 2018, 148, 124902 .
AMA StyleYohei Nakanishi, Ryohei Ishige, Hiroki Ogawa, Keita Sakakibara, Kohji Ohno, Takashi Morinaga, Takaya Sato, Toshiji Kanaya, Yoshinobu Tsujii. USAXS analysis of concentration-dependent self-assembling of polymer-brush-modified nanoparticles in ionic liquid: [I] concentrated-brush regime. The Journal of Chemical Physics. 2018; 148 (12):124902.
Chicago/Turabian StyleYohei Nakanishi; Ryohei Ishige; Hiroki Ogawa; Keita Sakakibara; Kohji Ohno; Takashi Morinaga; Takaya Sato; Toshiji Kanaya; Yoshinobu Tsujii. 2018. "USAXS analysis of concentration-dependent self-assembling of polymer-brush-modified nanoparticles in ionic liquid: [I] concentrated-brush regime." The Journal of Chemical Physics 148, no. 12: 124902.
Hidemitsu Furukawa, Takaya Sato, and co-workers describe a highly robust and low frictional double-network ion gel in article number 1700074. Ionic liquids (ILs) provide robustness on lubricant gels. Double network hydrogels with high toughness and low friction have prevented their industrial usage by water evaporation. The combination of ILs and its compatible polymers result in an ion gel with high compression strength (30 MPa) and stability under high temperature (80 °C) or vacuum (2.2 × 10−4 Pa).
Hiroyuki Arafune; Saika Honma; Takashi Morinaga; Toshio Kamijo; Miki Miura; Hidemitsu Furukawa; Takaya Sato. Tribology: Highly Robust and Low Frictional Double-Network Ion Gel (Adv. Mater. Interfaces 9/2017). Advanced Materials Interfaces 2017, 4, 1 .
AMA StyleHiroyuki Arafune, Saika Honma, Takashi Morinaga, Toshio Kamijo, Miki Miura, Hidemitsu Furukawa, Takaya Sato. Tribology: Highly Robust and Low Frictional Double-Network Ion Gel (Adv. Mater. Interfaces 9/2017). Advanced Materials Interfaces. 2017; 4 (9):1.
Chicago/Turabian StyleHiroyuki Arafune; Saika Honma; Takashi Morinaga; Toshio Kamijo; Miki Miura; Hidemitsu Furukawa; Takaya Sato. 2017. "Tribology: Highly Robust and Low Frictional Double-Network Ion Gel (Adv. Mater. Interfaces 9/2017)." Advanced Materials Interfaces 4, no. 9: 1.
Reducing friction is important to improve the lifetime and energy efficiency of mechanical systems. Since human joints with gel-like structure possess a coefficient of friction as low as 10–3, gel materials are recognized as a useful example for designing low frictional materials. Ion gels incorporating ionic liquids (ILs) as swelling agent is expected to be stable gel lubricant since high thermal stability and negligible volatility of ILs can maintain swelled state of gels even under harsh conditions. In this study, we newly synthesized a double network (DN) ion gel composed of an ionic liquid, N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis (trifluoromethylsulfonyl)imide (DEME-TFSI) and an ionic liquid polymer composed of the derivative of DEME-TFSI, poly (N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis (trifluoromethylsulfonyl)imide) as a first network and neutral poly(methyl methacrylate) as a second network. The obtained DN ion gel showed high compression strength and it was thermally stable until 300 °C. The stable COF after repeated measurements at high temperature or vacuum conditions showed the durability of DN ion gels even under harsh conditions. The results obtained in this study shed light on the fabrication of lubricant gels with high mechanical strength and robustness, which are expected to be new candidates for enegy conservation.
Hiroyuki Arafune; Saika Honma; Takashi Morinaga; Toshio Kamijo; Miki Miura; Hidemitsu Furukawa; Takaya Sato. Highly Robust and Low Frictional Double-Network Ion Gel. Advanced Materials Interfaces 2017, 4, 1 .
AMA StyleHiroyuki Arafune, Saika Honma, Takashi Morinaga, Toshio Kamijo, Miki Miura, Hidemitsu Furukawa, Takaya Sato. Highly Robust and Low Frictional Double-Network Ion Gel. Advanced Materials Interfaces. 2017; 4 (9):1.
Chicago/Turabian StyleHiroyuki Arafune; Saika Honma; Takashi Morinaga; Toshio Kamijo; Miki Miura; Hidemitsu Furukawa; Takaya Sato. 2017. "Highly Robust and Low Frictional Double-Network Ion Gel." Advanced Materials Interfaces 4, no. 9: 1.
In this article, we propose a versatile method to prepare epoxy resin-based monolith membrane without any surface skin layer through polymerization induced spinodal type phase separation using a poly(vinyl alcohol) sacrificial film, where the monolith is a porous material with a bicontinuous skeletal structure. In this article, we propose a versatile method to prepare epoxy resin-based monolith membrane without any surface skin layer through polymerization induced spinodal type phase separation using a poly(vinyl alcohol) sacrificial film, where the monolith is a porous material with a bicontinuous skeletal structure. The resulting monolith membranes exhibit well-defined pore sizes, and high mechanical strength, thermal stability, and ionic conductivity in liquid electrolytes. A block copolymer has been applied to control the pore size to be at the mesoscale, and surface skinless freestanding monolith membrane have been developed. To improve the mechanical properties, cellulose nanofibers are introduced as a reinforcing filler. The monolith membranes are thermally resistant at least up to 200 °C. The ionic conductivity of the monolith membranes (0.71 mS cm −1 at 25 °C) is comparable to those of commonly used polyolefin separators. The results that are presented here demonstrate that polymer monolith membranes have bright prospects as novel separators for lithium ion batteries, fuel cells, etc.
Keita Sakakibara; Hideki Kagata; Norio Ishizuka; Takaya Sato; Yoshinobu Tsujii. Fabrication of surface skinless membranes of epoxy resin-based mesoporous monoliths toward advanced separators for lithium ion batteries. Journal of Materials Chemistry A 2017, 5, 6866 -6873.
AMA StyleKeita Sakakibara, Hideki Kagata, Norio Ishizuka, Takaya Sato, Yoshinobu Tsujii. Fabrication of surface skinless membranes of epoxy resin-based mesoporous monoliths toward advanced separators for lithium ion batteries. Journal of Materials Chemistry A. 2017; 5 (15):6866-6873.
Chicago/Turabian StyleKeita Sakakibara; Hideki Kagata; Norio Ishizuka; Takaya Sato; Yoshinobu Tsujii. 2017. "Fabrication of surface skinless membranes of epoxy resin-based mesoporous monoliths toward advanced separators for lithium ion batteries." Journal of Materials Chemistry A 5, no. 15: 6866-6873.
This chapter provides an overview of the fundamental concepts concerning the synthesis and properties of a “concentrated” polymer brush (CPB) followed by our recent research topics regarding self-organization of CPB-modified nanoparticles, their application to solid electrolytes along with ionic liquids, and then their practical use in various electrochemical devices including a lithium ion battery, an electric double-layer capacitor, a dye-sensitized solar cell, and a polymer electrolyte fuel cell. A CPB is one type of polymer brushes, and its controlled synthesis and hence systematic study were achieved by living radical polymerization (LRP) or reversible-deactivation radical polymerization. Since the graft chains of CPB have a highly elongated and oriented conformation in a good solvent, and hence potentially, the CPB exhibits favorable characteristics on their own. However, the LRP method has a limitation in the range of the controllable molecular weight of thereby synthesized polymers and hence the thickness of CPBs, i.e., on the order of 100 nm, limiting their use for a wider range of applications. In order to overcome this issue, CPBs have recently been successfully built up to a new hierarchical nano-system via self-ordering, as building blocks, nanoparticles/rods/sheets with CPBs on their surfaces. Among others, we here focus on the science and technology of CPB from the viewpoint of above-mentioned applications, otherwise difficult to achieve high performance.
Yoshinobu Tsujii; Yohei Nakanishi; Ryohei Ishige; Kohji Ohno; Takashi Morinaga; Takaya Sato. Development of Novel Nano-systems for Electrochemical Devices by Hierarchizing Concentrated Polymer Brushes. Intelligent Nanosystems for Energy, Information and Biological Technologies 2016, 195 -215.
AMA StyleYoshinobu Tsujii, Yohei Nakanishi, Ryohei Ishige, Kohji Ohno, Takashi Morinaga, Takaya Sato. Development of Novel Nano-systems for Electrochemical Devices by Hierarchizing Concentrated Polymer Brushes. Intelligent Nanosystems for Energy, Information and Biological Technologies. 2016; ():195-215.
Chicago/Turabian StyleYoshinobu Tsujii; Yohei Nakanishi; Ryohei Ishige; Kohji Ohno; Takashi Morinaga; Takaya Sato. 2016. "Development of Novel Nano-systems for Electrochemical Devices by Hierarchizing Concentrated Polymer Brushes." Intelligent Nanosystems for Energy, Information and Biological Technologies , no. : 195-215.
A polymerizable ionic liquid, N,N-diethyl-N-(2-methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEMM-TFSI), was polymerized via copper-mediated atom transfer radical polymerization (ATRP). The polymerization proceeded in a living manner producing well-defined poly(DEMM-TFSI) of target molecular weight up to about 400 K (including a polycation and an counter anion). The accurate molecular weight as determined by a GPC analysis combined with a light scattering measurement, and the molecular weight values obtained exhibited good agreement with the theoretical values calculated from the initial molar ratio of DEMM-TFSI and the monomer conversion. Surface-initiated ATRP on the surface of monodisperse silica particles (SiPs) with various diameters was successfully performed, producing SiPs grafted with well-defined poly(DEMM-TFSI) with a graft density as high as 0.15 chains/nm2. Since the composite film made from the silica-particle-decorated polymer brush and ionic liquid shows a relatively high ionic conductivity, we have evaluated the relationship between the grafted brush chain length and the ionic conductivity.
Takashi Morinaga; Saika Honma; Takeo Ishizuka; Toshio Kamijo; Takaya Sato; Yoshinobu Tsujii. Synthesis of Monodisperse Silica Particles Grafted with Concentrated Ionic Liquid-Type Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization for Use as a Solid State Polymer Electrolyte. Polymers 2016, 8, 146 .
AMA StyleTakashi Morinaga, Saika Honma, Takeo Ishizuka, Toshio Kamijo, Takaya Sato, Yoshinobu Tsujii. Synthesis of Monodisperse Silica Particles Grafted with Concentrated Ionic Liquid-Type Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization for Use as a Solid State Polymer Electrolyte. Polymers. 2016; 8 (4):146.
Chicago/Turabian StyleTakashi Morinaga; Saika Honma; Takeo Ishizuka; Toshio Kamijo; Takaya Sato; Yoshinobu Tsujii. 2016. "Synthesis of Monodisperse Silica Particles Grafted with Concentrated Ionic Liquid-Type Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization for Use as a Solid State Polymer Electrolyte." Polymers 8, no. 4: 146.
To evaluate the friction properties of new lubrication systems, two types of ammonium-based ionic liquids (ILs), N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate ([DEME][BF4]) and N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide ([DEME][TFSI]), to evaluate the friction properties of lubrication systems were investigated by the resonance shear measurements (RSM) and reciprocating type tribotests between silica (glass) surfaces. RSM revealed that an ILs layer of ca. 2 nm in thickness was maintained between the silica surfaces under an applied load of 0.40 mN~1.2 mN, where the friction of the system, the relative intensity was lower for [DEME][BF4], 0.12, than that of [DEME][TFSI], 0.18. On the other hand, the friction coefficients μk obtained from the tribotests of [DEME][BF4] were lower than that of [DEME][TFSI] for sliding velocitties in the range of 5.0×10(-4) m s(-1) to 3.0 ×10(-2) m s(-1) under applied loads of 196 mN-980 mN. The friction coefficients obtained by the tirbotests are discussed with reference to the RSM results.
Toshio Kamijo; Hiroyuki Arafune; Takashi Morinaga; Saika Honma; Takaya Sato; Masaya Hino; Masashi Mizukami; Kazue Kurihara. Lubrication Properties of Ammonium-Based Ionic Liquids Confined between Silica Surfaces Using Resonance Shear Measurements. Langmuir 2015, 31, 13265 -13270.
AMA StyleToshio Kamijo, Hiroyuki Arafune, Takashi Morinaga, Saika Honma, Takaya Sato, Masaya Hino, Masashi Mizukami, Kazue Kurihara. Lubrication Properties of Ammonium-Based Ionic Liquids Confined between Silica Surfaces Using Resonance Shear Measurements. Langmuir. 2015; 31 (49):13265-13270.
Chicago/Turabian StyleToshio Kamijo; Hiroyuki Arafune; Takashi Morinaga; Saika Honma; Takaya Sato; Masaya Hino; Masashi Mizukami; Kazue Kurihara. 2015. "Lubrication Properties of Ammonium-Based Ionic Liquids Confined between Silica Surfaces Using Resonance Shear Measurements." Langmuir 31, no. 49: 13265-13270.
Nonvolatile liquids and smooth surfaces are shown to preserve polymer brushes by Y. Tsujii, T. Sato and co-workers in article number 1500187. The development of a robust low friction system has been intensively investigated to improve the lifetime and energy efficiency of mechanical systems. A smooth glass material is applied onto ionic liquid polymer brushes, resulting in low frictional properties (μmin ≈ 10−3), high load bearing (14.7 N), and repeatable measurements (4000 cycles) on the macroscale.
Hiroyuki Arafune; Toshio Kamijo; Takashi Morinaga; Saika Honma; Takaya Sato; Yoshinobu Tsujii. Polymer Brushes: A Robust Lubrication System Using an Ionic Liquid Polymer Brush (Adv. Mater. Interfaces 15/2015). Advanced Materials Interfaces 2015, 2, 1 .
AMA StyleHiroyuki Arafune, Toshio Kamijo, Takashi Morinaga, Saika Honma, Takaya Sato, Yoshinobu Tsujii. Polymer Brushes: A Robust Lubrication System Using an Ionic Liquid Polymer Brush (Adv. Mater. Interfaces 15/2015). Advanced Materials Interfaces. 2015; 2 (15):1.
Chicago/Turabian StyleHiroyuki Arafune; Toshio Kamijo; Takashi Morinaga; Saika Honma; Takaya Sato; Yoshinobu Tsujii. 2015. "Polymer Brushes: A Robust Lubrication System Using an Ionic Liquid Polymer Brush (Adv. Mater. Interfaces 15/2015)." Advanced Materials Interfaces 2, no. 15: 1.
Hiroyuki Arafune; Toshio Kamijo; Takashi Morinaga; Saika Honma; Takaya Sato; Yoshinobu Tsujii. A Robust Lubrication System Using an Ionic Liquid Polymer Brush. Advanced Materials Interfaces 2015, 2, 1 .
AMA StyleHiroyuki Arafune, Toshio Kamijo, Takashi Morinaga, Saika Honma, Takaya Sato, Yoshinobu Tsujii. A Robust Lubrication System Using an Ionic Liquid Polymer Brush. Advanced Materials Interfaces. 2015; 2 (15):1.
Chicago/Turabian StyleHiroyuki Arafune; Toshio Kamijo; Takashi Morinaga; Saika Honma; Takaya Sato; Yoshinobu Tsujii. 2015. "A Robust Lubrication System Using an Ionic Liquid Polymer Brush." Advanced Materials Interfaces 2, no. 15: 1.