研究者データベース
| 中村 聡(ナカムラ サトシ) |
| 電子科学研究所 生命科学研究部門 |
| 特任助教 |
Last Updated :2024/05/09
研究活動情報
論文
- Satoshi Nakamura, Hiroshi Kakiuchida, Masahisa Okada, Atsushi HozumiAdvanced Functional Materials 2023年10月25日 [査読有り]
Abstract It is generally believed that water droplets on (super)hydrophilic surfaces is spread and strongly pin to the surface. The surface chemistry that achieves the paradoxical surface properties of being statically very hydrophilic, but exhibiting outstanding water sliding properties, has not yet established. Here, a facile approach to prepare such unusual surfaces based on a combination of a sol–gel process using an organosilane containing polyethylene glycol units and tetraethoxysilane, and subsequent alkali‐treatment is reported. The resulting sol–gel thin films are smooth, transparent, hydrophilic (static contact angle (CA) (θS) of ≈37°) and show a liquid‐like nature with both low CA hysteresis (≈4°) and sliding angle (α) for 10 µL water droplets (≈10°). Surprisingly, after alkali‐treatment for sufficient time, the surface becomes very hydrophilic (θS of ≈14°) while improving its dynamic wetting behaviors (CA hysteresis of ≈3° and α for 10 µL water droplet of ≈4°), such that even a mere 0.5 µL water drop can slide down smoothly without pinning and/or tailing. - Jasmine V Buddingh, Satoshi Nakamura, Guojun Liu, Atsushi HozumiLangmuir : the ACS journal of surfaces and colloids 2022年09月06日Accumulations of ice on modern infrastructures often cause severe consequences. As such, there is significant interest in developing functional coatings/surfaces that can prevent this. One such approach has been demonstrated with slippery liquid-infused porous surfaces (SLIPS) and organogels where the ice adhesion strength is reduced to the critical point (less than 10 kPa) where it can be removed by natural forces such as gravity, wind, vibrations, and so forth. However, both designs are limited by lubricant depletion. If lubricant release and reabsorption (syneresis) of organogels can be arbitrarily controlled by the surrounding temperature, the loss due to unfavorable evaporation and drainage of infused lubricants can be minimized and its durability can be extended. This study demonstrates the tunable thermo-responsive syneresis of transparent fluorinated organogels (F-ORGs) prepared from a commercial silicone elastomer and a lubricant mixture of fluorinated silicone oil and either poly(dimethylsiloxane) or poly(methylphenylsiloxane). By carefully tuning the ratio of the two lubricants in the mixture, the corresponding F-ORGs demonstrated arbitrarily tunable critical syneresis temperatures from -15 to 40 °C, below which the lubricant is released on the surface and above which the lubricant is re-absorbed. The resulting surfaces showed not only exceptionally long-lasting/repeatable low ice adhesion strengths (≤10 kPa over 50 icing/de-icing cycles) but also significant improvements in their repellency toward a variety of organic liquids. Compared to non-fluorinated organogels, F-ORGs could offer improved protection against outdoor pollutants to further enhance their practicality.
- Satoshi Nakamura, Yusuke Yamauchi, Atsushi HozumiLangmuir : the ACS journal of surfaces and colloids 38 24 7611 - 7617 2022年06月21日The development of self-healing systems for artificial superhydrophobic materials/surfaces based on the reconstruction of surface topologies rather than chemical makeup has been much less established. In this article, we report for the first time a simple and straightforward method for self-repairing surface dewettability over a long period of time by rapidly regenerating surface microstructures. We selected paraffin wax as a matrix for methyltrichlorosilane (MTCS) having strong reactivity with moisture/water and simply mixed them. When the as-prepared MTCS-loaded paraffin wax surfaces were exposed to air for a few hours, they spontaneously became highly hydrophobic with water contact angles of about 150° due to the formation of disordered surface microstructures. The use of paraffin wax with a few angstrom-scale space as a matrix was found to be more effective than the use of poly(dimethylsiloxane) with nanometer-size porosity in preventing both evaporation and degradation of MTCS's chemical reactivity for a long period. Therefore, for about 1 month, even after the surface microstructures were completely destroyed, surface dewettability could be self-repaired by rapidly regenerating surface morphologies. In addition, chemical damage by UV/ozone exposure could also be repeatably self-healed by the reconstruction of surface chemical makeup. We thus expect that this simple approach could provide future insights to impart the self-healing ability of manmade superhydrophobic materials/surfaces against chemical and physical damages.
- Satoshi Nakamura, Hideyuki Mitomo, Shigeaki Suzuki, Yu Torii, Yu Sekizawa, Yusuke Yonamine, Kuniharu IjiroCHEMISTRY LETTERS 51 5 529 - 532 2022年05月Assemblies of cationic gold nanorods (AuNRs) via electrostatic interactions with double-stranded (ds) DNA were investigated in solution and after evaporation as a cast-film. Interestingly, moderately positively charged AuNRs assembled with dsDNA provided a monolayer sheet with an ordered alignment resembling a two-dimensional (2D) smectic structure during solvent evaporation.
- Masaki Matsuzaki, Yusuke Yamauchi, Satoshi Nakamura, Tomoya Sato, Chihiro Urata, Atsushi HozumiMOLECULAR CRYSTALS AND LIQUID CRYSTALS 728 1 1 - 9 2021年10月We have developed functional films capable of retaining anticorrosive properties even after severe mechanical damage which directly exposes the metal surface to corrosive environments. It was found that functional films prepared by simply dispersing mesoporous silica-nanocontainers loaded with a corrosion inhibitor, tolyltriazole, in a commercially available aqueous polyurethane solution could effectively prevent the corrosion of copper substrates. Even after cutting of the films and submersion in aqueous sodium chloride, no serious oxidation of the damaged areas was observed for up to four months. The transparency of the resulting polyurethane films remained almost unchanged with or without the addition of MPS-NCs/TTA.
- Satoshi Nakamura, Javier A. Luna, Hiroshi Kakiuchida, Atsushi HozumiLANGMUIR 37 40 11771 - 11780 2021年10月Surface modifications for easy removal of liquids and solids from various metal surfaces are much less established than for silicon (Si) or glass substrates. Trimethylsiloxy-terminated polymethylhydrosiloxane (PMHS) is very promising because it can be directly immobilized covalently to a wide variety of metal surfaces by simply heating neat PMHS liquid, resulting in a film showing excellent dynamic omniphobicity. However, such PMHS films are easily degraded by hydrolytic attack in an aqueous environment. In this study, we have successfully improved the hydrolytic stability of the PMHS-covered ultrasmooth metal (Ti, Al, Cr, Ni, and Cu) surfaces by end-capping of the residual Si-H groups of the PMHS films with vinyl-terminated organosilanes, for example, trimethylvinylsilane (TMVS), through a platinum-catalyzed hydrosilylation reaction. The resulting TMVS-capped PMHS film surfaces showed significantly greater stability even after submersion in water for 6 days, with their excellent dynamic dewetting behavior toward water, toluene, n-hexadecane, and ethanol changing little. In addition, they also showed reasonable anti-icing (icephobic) properties with low ice-adhesion strength of less than 50 kPa even after 20 cycles of testing at -15 degrees C.
- Satoshi Nakamura, Hideyuki Mitomo, Kuniharu IjiroCHEMISTRY LETTERS 50 2 361 - 370 2021年02月Inorganic nanoparticles are an attractive material that shows unique properties that differ from their bulk counterparts. Assembly of nanoparticles with soft materials is an effective approach to leverage their unusual properties for the fabrication of functional devices. Among the various soft materials, polymer brushes are expected to offer exciting opportunities due to their unique conformational properties. Here, we review research progress in the assembly and active control of gold nanoparticles with polymer brushes as a scaffold.
- Satoshi Nakamura, Javier A. Luna, Atsushi HozumiJournal of Photopolymer Science and Technology 34 6 639 - 650 2021年
- Satoshi Nakamura, Richard J. Archer, Gary J. Dunderdale, Atsushi HozumiJOURNAL OF HAZARDOUS MATERIALS 398 2020年11月From a viewpoint of reducing the burden on both human health and the environment, alternative surface modification techniques for preparing highly water-repellent surfaces without the use of environmentally da-maging perfluorocarbons are highly desirable. Among them, the development of hydrophilic surfaces showing superior water sliding/removal properties has been scarcely reported. In this study, we have successfully de-monstrated the fabrication of smooth, transparent, and hydrophilic pegylated organosilanes (PEGn-Si, CH3O-(C2H4O)n-C3H6-Si(OCH3)(3) where n = 3, 6-9, 9-12)-derived hybrid films showing excellent water sliding/re-moval properties using a simple sol-gel reaction of PEGn-Si and tetraethoxysilane (TEOS, Si(OC2H5)(4)). The final static/dynamic surface wetting properties of the samples were found to be significantly influenced by both the PEG chain length and their mixing ratios. The use of PEGn-Si with the longest PEG chain (n = 9-12) was found to be effective for improving water sliding/removal properties. Small volume water droplets (5 mu L) on the PEG(9-12-) Si/TEOS hybrid film (static water contact angle (CA) of similar to 40 degrees) ata 90 degrees-inclined surface could slide atan average speed of 3.4 mm/sec without pinning and tailing, which was about twice as fast as that on the PEG(6-9)-Si/TEOS hybrid film surface (1.5 mm/sec, static water CA of similar to 40 degrees), in spite of having similar static hydrophilic nature.
- Yu Sekizawa, Hideyuki Mitomo, Mizuki Nihei, Satoshi Nakamura, Yusuke Yonamine, Akinori Kuzuya, Takehiko Wada, Kuniharu IjiroNANOSCALE ADVANCES 2 9 3798 - 3803 2020年09月Nanoparticles exhibit a number of unique properties such as localized surface plasmon resonance (LSPR). As this LSPR is sensitive to geometrical or spatial conditions, the arrangement of nanoparticles, in particular the active arrangement of plasmonic structures, is an important issue. In this study, gold nanorod (GNR) arrays were prepared by GNR attachment on anionic polymer (DNA) brushes via electrostatic interactions and their stimuli-responsive changes in orientationwere investigated. As a result, the orientation of GNR arrays on DNA brushes reversibly changed by the modulation of electrostatic interactions between GNRs and polymers via changes in the solution pH. As these extensive GNR arrays are prepared via easy bottom-up processes, GNR surface properties are easily tuned by simple modification, and DNAs could be replaced with various synthetic polymers, we believe that this study will lead to the development of nextgeneration materials and devices with actively tunable structures.
- Satoshi Nakamura, Brandon Becher-Nienhaus, Takayuki Miyamae, Atsushi HozumiJournal of nanoscience and nanotechnology 20 8 5211 - 5216 2020年08月01日Studies on hydrophilic surfaces showing excellent water sliding properties are very rare, despite the numerous practical advantages they offer. One of the authors has recently developed a smooth, transparent and sufficiently-thick hydrophilic film with low contact angle hysteresis (5°) and small water tilt angles (6 ± 2°) through a simple sol-gel reaction of 2-[methoxy (ethyleneoxy)10propyl]trimethoxysilane (PEG-M) and tetraethoxysilane (TEOS). However, the origins of these unusual water sliding properties have not been clearly identified. As such, the impact of the addition of TEOS acting as a "nanospacer" or the identity of PEG terminal functional groups on the final static/dynamic wetting properties needs to be explored. In this study, we investigated the orientational/conformational states of PEG chains in PEG-M/TEOS and [hydroxy(ethyleneoxy)8-12propyl]triethoxysilane (PEG-OH)/TEOS hybrid films under wet and dry conditions using sum-frequency generation (SFG) spectroscopy. We found that PEG-M/TEOS hybrid film surfaces had no marked differences in the conformational states of PEG chains under wet or dry conditions, resulting in excellent water sliding properties as there was no energy barrier for water droplet motion. In contrast, PEG chains were completely disordered after contact with water in the PEG-OH/TEOS hybrid films due to hydration effects. This large conformational change between the liquid/solid and gas/solid interface at the three-phase contact line resulted in an unfavorable energetic barrier for water droplet motion, leading to the poor water sliding properties. TEOS did not physically work as a "nanospacer," but chemically worked as a binder to endow practically useful properties, such as good adhesion and versatility in substrates used, to our hybrid films.
- Satoshi Nakamura, Hideyuki Mitomo, Yusuke Yonamine, Kuniharu IjiroCHEMISTRY LETTERS 49 7 749 - 752 2020年07月In this study, we demonstrate that the plasmonic properties of gold nanorods (GNRs) electrostatically adsorbed on a DNA brush substrate are reversibly controlled by changes in NaCl concentration. This plasmonic change results from GNR assembly/disassembly in a DNA brush layer. In addition, we show that this active plasmonic system exhibits intense and switchable chiroptical properties.
- Satoshi Nakamura, Hideyuki Mitomo, Yu Sekizawa, Takeshi Higuchi, Yasutaka Matsuo, Hiroshi Jinnai, Kuniharu IjiroLangmuir : the ACS journal of surfaces and colloids 36 13 3590 - 3599 2020年04月07日The development of a strategy for the assembly of nanoscale building blocks, in particular, anisotropic nanoparticles, into desired structures is important for the construction of functional materials and devices. However, control over the orientation of rod-shaped nanoparticles on a substrate for integration into solid-state devices remains challenging. Here, we report a strategy for the fabrication of finely aligned gold nanorod (GNR) arrays using polymer (DNA) brushes as a nanoscale template. The gold nanorods modified with cationic surface ligands were electrostatically adsorbed onto the DNA brush substrates under various conditions. The orientational behavior of the GNRs was examined by spectral analyses and transmission electron microtomography (TEMT). As a result, we found several important factors, such as moderate interaction between GNRs and polymers and polymer densities on the substrate, related to the vertical alignment of GNRs on the substrates. We also developed a purification method to remove the undesired adsorption of GNRs onto the arrays. Finally, we have succeeded in the fabrication of extensive vertical GNR arrays of high quality via the easy bottom-up process.
- Satoshi Nakamura, Hideyuki Mitomo, Miho Aizawa, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Andrew Pike, Masayuki Naya, Atsushi Shishido, Kuniharu IjiroACS omega 4 15 16701 - 16701 2019年10月08日[This corrects the article DOI: 10.1021/acsomega.7b00303.].
- Hideyuki Mitomo, Satoshi Nakamura, Yasunobu Suzuki, Yasutaka Matsuo, Kenichi Niikura, Kuniharu IjiroJOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY 17 12 8995 - 9001 2017年12月In this study, we have prepared double-stranded DNA brushes on glass or quartz substrates through the immobilization of biotinylated oligo-DNA, followed by hybridization and polymerization of the DNA by a surface-initiated enzymatic polymerization method. The density of the DNA brush was calculated based on UV spectra and agarose gel electrophoresis. Prepared DNA brushes showed a relatively high density of DNA chains (over 1500 chains/mu m(2)) independent of the length of the DNA. Atomic force microscopy of the 2D-patterned DNA brushes indicated dynamic changes in height under various salt concentrations. These results provided insight into the conformation of DNA brushes.
- Satoshi Nakamura, Hideyuki Mitomo, Miho Aizawa, Takeharu Tani, Yasutaka Matsuo, Kenichi Niikura, Andrew Pike, Masayuki Naya, Atsushi Shishido, Kuniharu IjiroACS omega 2 5 2208 - 2213 2017年05月31日Control over the orientation of metal nanorods is important for both fundamental and applied research. We show that gold nanorods (GNRs) can be aligned in a single direction by adsorbing positively charged GNRs onto a double-strand DNA-grafted substrate through electrostatic interaction. The ordered structure can be optimized by controlling the density of the positive charges on the surface of the GNRs. We found, in agreement with the results of theoretical simulation, that the resultant structure exhibits plasmonic properties that are dependent on the GNR orientation relative to the direction of an oscillating electric field. Our approach provides new insights into the polymer-assisted self-assembly of rod-shaped nanoparticles utilizing electrostatic interactions.