Updated on 2024/06/24

写真a

 
SAMITSU, Sadaki
 
Affiliation
Faculty of Science and Engineering, Graduate School of Advanced Science and Engineering
Job title
Professor(non-tenure-track)

Research Experience

  • 2024.04
    -
    Now

    Waseda University   Department of Nanoscience and Nanoengineering, Graduate School of Advanced Science and Engineering, Faculty of Science and Engineering   Professor (without tenure)

  • 2023.04
    -
    Now

    National Institute for Materials Science   Research Center for Macromolecules and Biomaterials, Data-driven Polymer Design Group   Principal Researcher

  • 2021.04
    -
    2024.03

    Waseda University   Department of Nanoscience and Nanoengineering, Graduate School of Advanced Science, Faculty of Science and Engineering and Technology

  • 2020.04
    -
    2023.03

    National Institute for Materials Science   Research and Services Division of Materials Data and Integrated System (MaDIS), Data-driven Polymer Design Group   Principal Researcher

  • 2018.04
    -
    2020.03

    National Institute for Materials Science   Research and Services Division of Materials Data and Integrated System (MaDIS), Data-driven Polymer Design Group   Senior Researcher

  • 2017.04
    -
    2018.03

    National Institute for Materials Science   Research Center for Structural Materials, Adhesive Materials Group   Senior Researcher

  • 2014.04
    -
    2017.03

    National Institute for Materials Science   Research Center for Functional Materials, Separation Functional Materials Group

  • 2009.04
    -
    2014.03

    National Institute for Materials Science   Organic Nanomaterials Center, Functional Thin Films Group   Researcher

  • 2006.04
    -
    2009.03

    Kyoto University   Graduate School of Science, Department of Physics I   Postdoctoral Fellow

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Education Background

  • 2003.04
    -
    2006.03

    The University of Tokyo   Graduate School of Engineering   Department of Applied Physics  

  • 2001.04
    -
    2003.04

    The University of Tokyo   Graduate School of Frontier Sciences   Advanced Materials Science  

  • 1997.04
    -
    2001.03

    The University of Tokyo   School of Engineering   Department of Applied Physics  

Committee Memberships

  • 2023.07
    -
    Now

    The Society of Polymer Science, Japan  An editorial committee member

  • 2020.04
    -
    Now

    The Society of Polymer Science, Japan  A committee member of a research group on basic property of polymers

  • 2022.07
    -
    2023.06

    Cabinet Office, Secretariat of Science, Technology and Innovation Policy  Administrative Practice Trainee

  • 2020.06
    -
    2022.06

    The Society of Polymer Science, Japan  A event committee member

  • 2010.04
    -
    2014.03

    高分子学会 茨城地区「若手の会」交流会  世話人

Professional Memberships

  •  
     
     

    The Society of Polymer Science, Japan

  •  
     
     

    The Society of Fiber Science and Technology Japan

Research Areas

  • Polymer materials / Biophysics, chemical physics and soft matter physics

Research Interests

  • polymer

  • materials informatics

  • porous materials

  • phase separation

  • nano crystallization

  • sound absorption

  • thermal insulator

  • separation membrane

  • X-ray CT

  • refractive index

  • mechanical property

  • fracture behavior

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Awards

  • Publicity Commitee Award

    2018.05   The 67th SPSJ Annual Meeting  

  • Young Scientist Lecture Award

    2017.07   The 63th annual Kobe Polymer Research Symposium  

  • Poster Presentation Award

    2016.05   The 24th Polymer Material Forum  

  • NIMS President Award for Young Scientist

    2015.04   National Institute for Materials Science  

  • Young Scientist Prize (Silver Medal)

    2015.04   Minister of Education, Culture, Sports, Science and Technology (MEXT)  

  • IPC2014 Young Scientist Poster Award

    2014.12   The 10th SPSJ International Polymer Conference  

  • GSC Poster Award

    2014.05   The 3rd JACI/GSC Symposium  

  • Outstanding Poster Presentation Award

    2006.12   The 7th International Conference on Nano-Molecular Electronics  

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Papers

  • Biobased chitosan-derived self-nitrogen-doped porous carbon nanofibers containing nitrogen-doped zeolites for efficient removal of uremic toxins during hemodialysis.

    I-Hsuan Yang, László Szabó, Makoto Sasaki, Koichiro Uto, Joel Henzie, Feng-Huei Lin, Sadaki Samitsu, Mitsuhiro Ebara

    International journal of biological macromolecules   253 ( Pt 3 ) 126880 - 126880  2023.09  [International journal]

     View Summary

    Highly efficient adsorbents are needed to remove uremic toxins and reduce the economic and societal burden of the current dialysis treatments in resource-limited environments. In this study, nanostructured porous carbon nanofibers with nitrogen-doped zeolites (NZ-PCNF) were prepared, by electrospinning zeolites with chitosan-poly(ethylene oxide) blends, followed by a one-step carbonization process, without further activation steps or aggressive chemical additives for N-doping. The results showed that N-zeolites were successfully integrated into an ultrafine carbon nanofiber network, with a uniform nanofiber diameter of approximately 25 nm, hierarchical porous structure (micro- and mesopores), and high specific surface area (639.29 m2/g), facilitating uremic toxin diffusion and adsorption. The self-N-doped structure in the NZ-PCNF removed more creatinine (∼1.8 times) than the porous carbon nanofibers when using the same weight of precursor materials. Cytotoxicity and hemolysis tests were performed to verify the safety of NZ-PCNF. This study provides a novel strategy for transforming chitosan-based materials into state-of-the-art porous carbon nanofiber/zeolite self-N-doped composites, affording an efficient bioderived adsorbent for the removal of uremic toxins in patients with chronic kidney disease.

    DOI PubMed

    Scopus

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  • Hydrophilic amorphous crosslinked membranes with subnanometer pores prepared by plasma-enhanced chemical vapor deposition and their shape-selective alcohol permeation

    Sadaki Samitsu, Edhuan Ismail, Yoshihisa Fujii, Izumi Ichinose

    Journal of Membrane Science   680  2023.08

     View Summary

    High-density crosslinked polymer membranes several tens of nanometers thick were prepared by chemical vapor deposition (CVD) of propylamine (PA). Analysis by various methods showed that the densely crosslinked PA-CVD membranes had a composition of C3.0H4.7N0.8O0.4, and contained amine, imine, vinyl, and carbonyl functional groups. Positron annihilation lifetime spectroscopy and alcohol-retention studies showed that the crosslinked membranes had pore sizes of 0.3–0.7 nm. Their porosity was about 10%, as estimated from water-absorption experiments. By appropriate choice deposition conditions, the average pore diameter could be selected, and the porosity could be tuned in the range 1–18%. A membrane with 0.56 nm pores showed a significant difference in the retention factors of C3 and C4 alcohols, for example, showing a 77% retention of tert-butanol, three times that of n-butanol. The thickness of PA-CVD membranes could be reduced to 10 nm, and the membrane showed a high retention performance for divalent ions, a resistance to pressures of more than 40 bars, and a water flux of up to 170 L m−2 h−1. This comprehensive investigation of the effects of the CVD parameters will permit tuning of the thickness, pore size, porosity, and density of the hydrophilic crosslinked membranes.

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  • Exploring Potential of Adsorptive-Photocatalytic Molybdenum Disulphide/Polyacrylonitrile (MoS<inf>2</inf>/PAN) Nanofiber Coated Cellulose Acetate (CA) Membranes for Treatment of Wastewater

    Nur Shafiqah Jamaluddin, Nur Hashimah Alias, Juhana Jaafar, Nur Hidayati Othman, Samitsu Sadaki, Fauziah Marpani, Woei Jye Lau, Mohd Haiqal Abd Aziz

    Journal of Polymers and the Environment   30 ( 12 ) 5290 - 5300  2022.12

     View Summary

    Adsorptive-photocatalytic electrospun nanofiber membranes have received remarkable attention as they could provide an excellent solution for the effective treatment of wastewater. However, the mechanical properties of nanofiber have limited their use in pressure-driven filtration applications. In this study, dual-layered MoS2/PAN-CA adsorptive-photocatalytic-based membranes have been successfully fabricated using molybdenum disulphide/polyacrylonitrile (MoS2/PAN) nanofiber coated porous cellulose acetate (CA) membranes. The fabricated CA membranes were coated with electrospun MoS2/PAN nanofiber via the electrospinning technique. Subsequently, hot-pressed treatment was applied to the fabricated membrane to form a stronger attachment between the CA and MoS2/PAN nanofiber layers. The physicochemical properties of the fabricated membranes were characterised using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyzer (TGA), water contact angle (WAC), porosity analysis, and tensile strength test. In addition, the membrane separation performance of the fabricated nanofiber membranes was evaluated in terms of water flux and contaminant rejection using a self-assembled cross-flow filtration system. The MoS2/PAN-CA membrane demonstrated improved physicochemical and structural properties where WAC, porosity and mechanical strength increased up to 38% (44.0°), 25% (55%) and 26% (32.1 MPa), respectively, as compared to pristine CA membrane. Upon hot-pressed treatment at a temperature of 120 °C, pure water flux of MoS2/PAN-CA membrane improved by 28% to 36.3 Lm−2 h−1. These improved properties of dual-layered adsorptive-photocatalytic MoS2/PAN-CA membranes recommend it as a potential membrane material to treat various pollutants in water and wastewater.

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  • Visualization of Flow‐Induced Strain Using Structural Color in Channel‐Free Polydimethylsiloxane Devices

    Kota Shiba, Chao Zhuang, Kosuke Minami, Gaku Imamura, Ryo Tamura, Sadaki Samitsu, Takumi Idei, Genki Yoshikawa, Luyi Sun, David A. Weitz

    Advanced Science   10 ( 1 ) 2204310 - 2204310  2022.11  [International journal]

     View Summary

    Measuring flow of gases is of fundamental importance yet is typically done with complex equipment. There is, therefore, a longstanding need for a simple and inexpensive means of flow measurement. Here, gas flow is measured using an extremely simple device that consists of an Ar plasma-treated polydimethylsiloxane (PDMS) slab adhered on a glass substrate with a tight seal. This device does not even have a channel, instead, gas can flow between the PDMS and the glass by deforming the PDMS wall, in other words, by making an interstice as a temporary path for the flow. The formation of the temporary path results in a compressive bending stress at the inner wall of the path, which leads to the formation of well-ordered wrinkles, and hence, the emergence of structural color that changes the optical transmittance of the device. Although it is very simple, this setup works sufficiently well to measure arbitrary gases and analyzes their flow rates, densities, and viscosities based on the change in color. It is also demonstrated that this technique is applicable to the flow-induced display of a pattern such as a logo for advanced applications.

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  • Highly stretchable and self-healable polymer gels from physical entanglements of ultrahigh–molecular weight polymers

    Yuji Kamiyama, Ryota Tamate, Takashi Hiroi, Sadaki Samitsu, Kenta Fujii, Takeshi Ueki

    Science Advances   8 ( 42 ) eadd0226  2022.10  [International journal]

     View Summary

    Highly stretchable and self-healing polymer gels formed solely by physical entanglements of ultrahigh–molecular weight (UHMW) polymers were fabricated through a facile one-step process. Radical polymerization of vinyl monomers in ionic liquids under very low initiator concentration conditions produced UHMW polymers of more than 10 6 g/mol with nearly 100% yield, resulting in the formation of physically entangled transparent polymer gels. The UHMW gels showed excellent properties, such as high stretchability, high ionic conductivity, and recyclability. Furthermore, the UHMW gel exhibited room temperature self-healing ability without any external stimuli. The tensile experiments and molecular dynamics simulations indicate that the nonequilibrium state of the fractured surfaces and microscopic interactions between the polymer chains and solvents play a vital role in the self-healing ability. This study provides a physical approach for fabricating stretchable and self-healing polymer gels based on UHMW polymers.

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  • Fabrication of mesoporous crystalline microparticles of poly(ether sulfone) via solvent-induced crystallization

    Sadaki Samitsu

    Polymer   248  2022.05

     View Summary

    Mesoporous polymer microparticles are promising for energy, environmental, and biomedical applications. A linear polymer microparticle is desirable from the perspective of polymer recycling. In this study, mesoporous crystalline microparticles of a commercially available high-performance polymer, poly(ether sulfone) (PES), were prepared. Solvent-induced crystallization of PES in nitrobenzene resulted in nearly spherical microparticles with an average size of 5 μm and narrow size distribution. The microstructure and mesoporosity of the microparticles were characterized with scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and nitrogen adsorption/desorption, which gave a pore size distribution peaking at 7 nm with a porosity of 0.44. Fourier-transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis confirmed the cocrystal of PES and nitrobenzene. The formation mechanism of the PES microparticles was elucidated based on the theory of polymer spherulite formation. This study gives an insight on solvent-induced crystallization of rigid high-Tg polymers useful for the mesoporous polymer particle fabrication.

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  • Freeze-Burn: Fabrication of Porous Carbon Networks via Polymer-Templated Rapid Thermal Annealing

    James Nicolas Pagaduan, Sadaki Samitsu, Jordan Varma, Todd Emrick, Reika Katsumata

    ACS Applied Polymer Materials   4 ( 6 ) 4329 - 4338  2022.04

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  • Effective Immobilization of Monomeric Methylene Blue on Hydroxyapatite Nanoparticles by Controlling Inorganic–Organic Interfacial Interactions

    Iori Yamada, Takuya Kataoka, Ryota Ikeda, Sadaki Samitsu, Motohiro Tagaya

    Inorganic Chemistry   61 ( 12 ) 4865 - 4878  2022.03  [International journal]

     View Summary

    We successfully synthesized methylene blue (MB+)-immobilized hydroxyapatite (HM) nanoparticles by changing the initial P/Ca molar ratio. The immobilized amount of MB+ increased with increasing the initial P/Ca molar ratio from 0.6 to 4.0, and the HM had an elliptical shape (long length, 21-24 nm; short length, 11-13 nm) irrespective of the initial P/Ca molar ratio. Upon increasing the initial P/Ca molar ratio, the number of carbonate ions on the HM surface decreased, which would be owing to the electrostatic repulsion by the surface phosphate ions (i.e., P-O-), the surface P-OH mainly dissociated to form P-O-, and the electrostatic interaction of P-O- with MB+ enhanced. The bonding of MB+ with surface P-OH and Ca2+ sites of hydroxyapatite would be hydrogen-bonding and Lewis acid-base interactions, respectively. The optimum synthesis condition for MB+ immobilization at the monomer state was found to be the initial P/Ca molar ratio of 2.0. Here, the existence percentage of the MB+ monomer and the molecular occupancy of the surface carbonate ion at the initial P/Ca molar ratio of 2.0 were higher than those at 4.0 with no significant difference in the immobilized amount of MB+, indicating that MB+ at the initial P/Ca molar ratio of 4.0 is more aggregated than that at 2.0. These results suggested that a part of carbonate ions has a role as a spacer to suppress MB+ aggregation. Accordingly, the interfacial interactions between the MB+ monomer and the hydroxyapatite surface were clarified, which can effectively be controlled by the initial P/Ca molar ratio. These findings will provide fundamental and useful knowledge for the design of calcium phosphate-organic nanohybrids. We believe that these particles will be the base materials to realize diagnostic and/or therapeutic functions through the molecular state control by optimizing the synthesis conditions.

    DOI PubMed

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  • Calibration for a count rate-dependent time correlation function and a random noise reduction in pulsed dynamic light scattering.

    Takashi Hiroi, Sadaki Samitsu, Hideaki Kano, Kunie Ishioka

    Analytical sciences : the international journal of the Japan Society for Analytical Chemistry   38 ( 3 ) 607 - 611  2022.03  [International journal]

     View Summary

    A pulsed dynamic light scattering (DLS) system, which would be potentially applied to nonlinear DLS with molecular selectivity, was developed by combining a sub-nanosecond pulsed laser with a software-based detection system. The distortion of the time correlation function due to the clipping effect in the photon counting module, and the resulting underestimation of the particle size, were successfully calibrated based on a theoretical simulation. The effective removal of random noises was also demonstrated via time gating synchronized to the laser pulses.

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    1
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  • Coordination State Control of Citric Acid Molecules on Europium(III) Ion-Doped Hydroxyapatite Nanoparticles for Highly Efficient Photoluminescence toward Biomedical Applications

    Takuya Kataoka, Takumi Hashimoto, Sadaki Samitsu, Zizhen Liu, Motohiro Tagaya

    ACS Applied Nano Materials   5 ( 2 ) 2305 - 2315  2022.02

    DOI

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    10
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  • Investigation of local structures of silicon oxynitride glasses prepared from aerogels

    Sadaki Samitsu

    Journal of Sol-Gel Science and Technology    2022

    DOI

  • Efficient chromium (VI) removal from wastewater by adsorption-assisted photocatalysis using MXene

    Sadaki Samitsu

    Journal of Environmental Chemical Engineering    2022

    DOI

  • Solvent Effects during the Flash-Freezing Fabrication of Mesoporous Polystyrenes

    Sadaki Samitsu, Sirawit Pruksawan, Hideaki Yokoyama, Izumi Ichinose

    Macromolecules    2022

     View Summary

    A polymer solution can be flash-frozen to prepare homopolymers with mesoporous structures in a template-free manner. The flash-freezing method is derived from the ice-templating or freeze-casting method. Herein, we comprehensively investigated the effects of 13 good solvents for polystyrene as well as the polystyrene concentration on the fabrication process. Solvents with high boiling-point-to-melting-point ratios yielded uniformly sized mesoporous polystyrenes at polymer concentrations ≥20 wt %. Such solvents provided a high specific surface area (328 m2/g) and a large mesopore volume (1.78 g/cm3) at the optimal polystyrene concentration. Solvents with medium-boiling-point-to-melting-point ratios formed bimodal mesopores, while a low polystyrene concentration gave hierarchical structures composed of mesopores and macropores. These results provide an understanding of the mechanism associated with the formation of mesopores and enable control over the desired mesopore morphology.

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  • Nanostructural control of transparent hydroxyapatite nanoparticle films using a citric acid coordination technique

    Zizhen Liu, Takuya Kataoka, Sadaki Samitsu, Daisuke Kawagoe, Motohiro Tagaya

    Journal of Materials Chemistry B   10 ( 3 ) 396 - 405  2022  [International journal]

     View Summary

    Control of the nanospaces of the hydroxyapatite nanoparticle films was successfully achieved using the citric acid coordination technique in a very simple way, which will provide a convenient bioceramic film preparation process.

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    6
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  • Controllable inverse design of auxetic metamaterials using deep learning

    Xiaoyang Zheng, Ta-Te Chen, Xiaofeng Guo, Sadaki Samitsu, Ikumu Watanabe

    MATERIALS & DESIGN   211  2021.12  [Refereed]

     View Summary

    As typical mechanical metamaterials with negative Poisson's ratios, auxetic metamaterials exhibit coun-terintuitive auxetic behaviors that are highly dependent on their geometric arrangements. The realization of the geometric arrangement required to achieve a negative Poisson's ratio relies considerably on the experience of designers and trial-and-error approaches. This report proposes an inverse design method for auxetic metamaterials using deep learning, in which a batch of auxetic metamaterials with a user-defined Poisson's ratio and Young's modulus can be generated by a conditional generative adversarial network without prior knowledge. The network was trained based on supervised learning using a large number of geometrical patterns generated by Voronoi tessellation. The performance of the network was demonstrated by verifying the mechanical properties of the generated patterns using finite element method simulations and uniaxial compression tests. The successful realization of user-desired properties can potentially accelerate the inverse design and development of mechanical metamaterials. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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  • Synthesis and Characterization of Titanium Dioxide Hollow Nanofiber for Photocatalytic Degradation of Methylene Blue Dye.

    Nurul Natasha Mohammad Jafri, Juhana Jaafar, Nur Hashimah Alias, Sadaki Samitsu, Farhana Aziz, Wan Norharyati Wan Salleh, Mohd Zamri Mohd Yusop, Mohd Hafiz Dzarfan Othman, Mukhlis A Rahman, Ahmad Fauzi Ismail, Takeshi Matsuura, Arun M Isloor

    Membranes   11 ( 8 )  2021.07  [International journal]

     View Summary

    Environmental crisis and water contamination have led to worldwide exploration for advanced technologies for wastewater treatment, and one of them is photocatalytic degradation. A one-dimensional hollow nanofiber with enhanced photocatalytic properties is considered a promising material to be applied in the field. Therefore, we synthesized titanium dioxide hollow nanofibers (THNF) with extended surface area, light-harvesting properties and an anatase-rutile heterojunction via a template synthesis method and followed by a calcination process. The effect of calcination temperature on the formation and properties of THNF were determined and the possible mechanism of THNF formation was proposed. THNF nanofibers produced at 600 °C consisted of a mixture of 24.2% anatase and 75.8% rutile, with a specific surface area of 81.2776 m2/g. The hollow nanofibers also outperformed the other catalysts in terms of photocatalytic degradation of MB dye, at 85.5%. The optimum catalyst loading, dye concentration, pH, and H2O2 concentration were determined at 0.75 g/L, 10 ppm, pH 11, and 10 mM, respectively. The highest degradation of methylene blue dye achieved was 95.2% after 4 h of UV irradiation.

    DOI PubMed

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    22
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  • Liquid Marble Patchwork on Super-Repellent Surface

    Mizuki Tenjimbayashi, Sadaki Samitsu, Yuko Watanabe, Yasuyuki Nakamura, Masanobu Naito

    Advanced Functional Materials   31 ( 21 )  2021.05

     View Summary

    Liquid marble (LM) is a droplet that is wrapped by hydrophobic solid particles, which behave as a non-wetting soft solid. Based on these properties, LM can be applied in fluidics and soft device applications. A wide variety of functional particles have been synthesized to form functional LMs. However, the formation of multifunctional LMs by integrating several types of functional particles is challenging. Here, a general strategy for the flexible patterning of functional particles on droplet surfaces in a patchwork-like design is reported. It is shown that LMs can switch their macroscopic behavior between a stable and active state on super-repellent surfaces in situ by jamming/unjamming the surface particles. Active LMs hydrostatically coalesce to form a self-sorted particle pattern on the droplet surface. With the support of LM handling robotics, on-demand cyclic activation–manipulation–coalescence–stabilization protocols by LMs with different sizes and particle types result in the reliable design of multi-faced LMs. Based on this concept, a single bi-functional LM is designed from two mono-functional LMs as an advanced droplet carrier.

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  • Bottlebrush polymer-reinforced transparent multiphase plastics with enhanced thermal stability

    Yoshihiro Yamauchi, Sadaki Samitsu, Kenta Goto, Masayuki Takeuchi

    Chemical Communications   56 ( 93 ) 14641 - 14644  2020.12  [International journal]

     View Summary

    © 2020 The Royal Society of Chemistry. Bottlebrush polymers (BPs) are highly tunable with regard to their glass transition temperature, refractive index, and shape. Herein, well-defined BPs were implemented as soft fillers to toughen multiphase plastics without loss of transparency and thermal stability, providing superior fracture toughness than a conventional linear polymer (LP). This study discloses a novel application of BPs and paves the way toward their further development. This journal is

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  • Effects of carbonization conditions on the microporous structure and high-pressure methane adsorption behavior of glucose-derived graphene

    Faten Ermala Che Othman, Sadaki Samitsu, Norhaniza Yusof, Ahmad Fauzi Ismail

    Korean Journal of Chemical Engineering   37 ( 11 ) 2068 - 2074  2020.11

     View Summary

    © 2020, The Korean Institute of Chemical Engineers. A simple, promising, environmentally friendly, and high yield technique to synthesize high specific surface area (SSA) and porous graphene-like materials from glucose precursor through carbonization and controlled chemical iron chloride (FeCl3) activation was demonstrated. Designing this nanoporous graphene-based adsorbent with high SSA, abundant micropore volume, tunable pore size distribution, and high adsorption capacity, is crucial in order to deal with the demands of large-scale reversible natural gas storage applications. Raman spectroscopy, BET method of analysis, and N2 adsorption/desorption measurements at 196 °C were adopted to evaluate the structural and textural properties of the resultant glucose derived-graphene (gluGr) samples. The effects of different carbonization conditions, such as the inert environments (argon, helium, and argon) and temperatures (700, 800, 900, and 1,000 °C), have been studied. A glucose-derived graphene carbonized under nitrogen environment at 700 °C (NGr700) with highly interconnected network of micropores and mesopores and large SSA (767 m2/g) exhibited excellent methane (CH4) storage property with exceptionally high adsorption capacity, superior to other glucose-derived graphene (gluGr) samples. A maximum volumetric capacity up to 42.08 cm3/g was obtained from CH4 adsorption isotherm at 25 °C and 35 bar. Note that the adsorption performance of the CH4 is highly associated with the SSA and microporosity of the gluGr samples, especially NGr700 that was successfully synthesized by FeCl3 activation under N2 environment.

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  • Methane adsorption by porous graphene derived from rice husk ashes under various stabilization temperatures

    Faten Ermala Che Othman, Mohd Shafri Ismail, Norhaniza Yusof, Sadaki Samitsu, Mohd Zamri Yusop, Nur Fatihah Tajul Arifin, Nur Hashimah Alias, Juhana Jaafar, Farhana Aziz, Wan Norharyati Wan Salleh, Ahmad Fauzi Ismail

    CARBON LETTERS   30 ( 5 ) 535 - 543  2020.10

     View Summary

    The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 degrees C, 200 degrees C, 300 degrees C, and 400 degrees C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 degrees C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 degrees C (1556.3 m(2)/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7 degrees indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm(3)/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

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  • Highly Transparent Benzothiazole-Based Block and Random Copolymers with High Refractive Indices by RAFT Polymerization

    Yugo Sato, Shigeki Sobu, Kazuhiro Nakabayashi, Sadaki Samitsu, Hideharu Mori

    ACS APPLIED POLYMER MATERIALS   2 ( 8 ) 3205 - 3214  2020.08

     View Summary

    The development of thermally stable, highly transparent polymers with superior refractive indices and Abbe's numbers are important for the further development of next-generation technology such as miniaturized opto-integrated devices and advanced lenses. Highly transparent benzothiazole-based copolymers having either block or random sequences and high refractive indices were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The conventional free-radical and RAFT copolymerizations of 2-benzothiazolyl vinyl sulfide (BTVS) and 2-vinylnaphthalene (VNA) produced random copolymers with adjustable BTVS contents between 8 and 54%. Chain extending the macrochain transfer agent, which was prepared by the RAFT polymerization of BTVS, with VNA was well-controlled, enabling the synthesis of block copolymers with high BTVS contents (up to 70%) and reasonable polymer yields (up to 60%). The benzothiazole-based homopolymer, poly(BTVS), exhibited a high refractive index (1.7432) and a reasonable Abbe's number (17.0). Excellent transmittances (>93%) of 400 nm light were observed for both copolymers composed of BTVS and VNA, and high refractive indices of 1.7178-1.6672 were achieved. The resulting benzothiazole-based copolymers exhibited high refractive indices (>1.7), high transparencies, tunable low glass-transition temperatures (T-g = 75-150 degrees C), and high thermal stabilities (T-d5 > 240 degrees C) by adjusting the chemical structure, composition, and sequence of the comonomer. This report presents development of the first high-refractive-index polymers derived from S-vinyl sulfide derivatives with benzothiazole side chains, exhibiting the synergistic effects of combining aromatic naphthalene and heteroaromatic benzothiazole units.

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  • Fabrication of porous (Ba,Sr)(Co,Fe)O3-delta (BSCF) ceramics using gelatinization and retrogradation phenomena of starch as pore-forming agent

    Kento Ishii, Makoto Shimizu, Haruki Sameshima, Sadaki Samitsu, Takamasa Ishigaki, Tetsuo Uchikoshi

    CERAMICS INTERNATIONAL   46 ( 9 ) 13047 - 13053  2020.06

     View Summary

    Porous (Ba,Sr)(Co,Fe)O3-delta (BSCF) ceramics with high open porosity and good electrical conductivity was fabricated using Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF), which shows a high mixed ionic-electronic conductivity. In general, during the fabrication of porous ceramics by the sacrificial template method using pore former particles, closed pores are easily formed unless sufficient pore former particles are added. In this study, we have devised a method using the gelatinization-retrogradation phenomena of starch for producing a porous body with an excellent percolated pore network structure. By dispersing BSCF and starch in an aqueous slurry (0-50% by weight) and heating, gelatinization of the starch occurred and the starch particles adhered to each other. Furthermore, in order to retain the percolated structure, the water solvent was removed by freeze-drying without heating to obtain a dried green body. The sintering behavior of the porous BSCF bodies prepared under various conditions was characterized by microstructural observations and relative density measurements. By optimizing the process conditions of the gelatinization and retrogradation, a porous body having an open porosity of 48.3%, and with 99% of the total pores open, was obtained. The matrix was also well connected and showed a sufficiently high conductivity which was similar to the porous bodies made by the traditional sacrificial template method.

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  • Toughening Effect of Rodlike Cellulose Nanocrystals in Epoxy Adhesive

    Sirawit Pruksawan, Sadaki Samitsu, Yoshihisa Fujii, Naoya Torikai, Masanobu Naito

    ACS APPLIED POLYMER MATERIALS   2 ( 3 ) 1234 - 1243  2020.03

     View Summary

    Epoxy structural adhesives have been used extensively in the automotive and aerospace industries to bond assembly parts. Much effort has been devoted to enhancing the mechanical properties of epoxy resin by incorporating fillers. Among a variety of fillers investigated for this purpose, nanocelluloses are regarded as a promising type of emerging green filler material because of their excellent mechanical and physicochemical properties. Indeed, nanocelluloses have been used as a filler for polymer nanocomposites. However, the toughening and reinforcing effects of nanocelluloses on rigid epoxy adhesives have not yet been fully revealed, particularly from the perspective of adhesive bonded joints. Here we report that epoxy adhesive containing cellulose nanocrystal (CNC) aggregates produced using a solvent-free ball milling method achieves drastically improved adhesive strength and fracture toughness compared with that of the reference adhesive without CNCs. The epoxy adhesive containing CNC aggregates exhibited an excellent adhesive strength of 29 MPa and a fracture toughness of 389 J/m(2), which were 125% and 378% greater than those of epoxy adhesive without CNCs, respectively.

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  • Efficient removal of partially hydrolysed polyacrylamide in polymer-flooding produced water using photocatalytic graphitic carbon nitride nanofibres

    Nur Hashimah Alias, Juhana Jaafar, Sadaki Samitsu, A. F. Ismail, M. H. D. Othman, Mukhlis A. Rahman, Nur Hidayati Othman, N. Yusof, F. Aziz, T. A. T. Mohd

    ARABIAN JOURNAL OF CHEMISTRY   13 ( 2 ) 4341 - 4349  2020.02

     View Summary

    In this work, graphitic carbon nitride (GCN) photocatalyst-incorporated polyacrylonitrile (PAN) nanofibres (GCN/PAN nanofibres) were successfully prepared using electrospinning technique. The physicochemical properties of the fabricated GCN/PAN nanofibres were analysed using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental analyser, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-vis-NIR spectroscopy. The photocatalytic degradation by GCN/PAN nanofibres exhibited 90.2% photodegradation of partially hydrolysed polyacrylonitrile (HPAM) after 180 min under UV light irradiation in a suspension photocatalytic reactor. The results suggest that the photodegradation of HPAM contaminant by GCN/PAN nanofibres was due to the synergetic effects of HPAM adsorption by the PAN nanofibres and HPAM photodegradation by the GCN. This study provides an insight into the removal of HPAM from polymer-flooding produced water (PFPW) through photocatalytic degradation of liquid-permeable self-supporting nanofibre mats as a potentially promising material to be used in industrial applications. (C) 2019 Production and hosting by Elsevier B.V. on behalf of King Saud University.

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    26
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  • Mechanistic insight of the formation of visible-light responsive nanosheet graphitic carbon nitride embedded polyacrylonitrile nanofibres for wastewater treatment

    Nur Hashimah Alias, Juhana Jaafar, Sadaki Samitsu, A. F. Ismail, Mohamad Azuwa Mohamed, M. H. D. Othman, Mukhlis A. Rahman, Nur Hidayati Othman, N. A. M. Nor, N. Yusof, F. Aziz

    JOURNAL OF WATER PROCESS ENGINEERING   33  2020.02

     View Summary

    Effective capture and in situ photodegradation of methylene blue (MB) dye is a promising technique to purify wastewater containing MB. With recently elicited ripples of discovery on graphitic carbon nitride (g-C3N4), this study investigates the performance of g-C3N4 on photodegradation of MB. In this study, polyacrylonitrile (PAN) nanofibres embedded with g-C3N4 photocatalyst was successfully prepared using electrospinning technique which produced liquid-permeable self-supporting photocatalytic nanofibre mats that can be handled easily. Different configurations of g-C3N4 were synthesised, bulk g-C3N4 (bg-C3N4) and nanosheets g-C3N4 (nsg-C3N4) from urea using a green facile template-free method. Effective photocatalytic activity of the g-C3N4 nanofibres was confirmed by 97.3% degradation of MB under visible light irradiation. Photodegradation of MB in aqueous solution by g-C3N4 nanofibres predominantly attributed to the synergetic effects of MB adsorption by PAN nanofibres and photocatalytic degradation of MB by g-C3N4 photocatalyst. This present work not only presents the simplest ecofriendly and economical approach to fabricate g-C3N4 nanofibre photocatalyst, but also paves new opportunities for this advanced photocatalyst as great potential in environmental remediation for treatment of industrial MB wastewater.

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  • Highly Luminescent Hydroxyapatite Nanoparticles Hybridized with Citric Acid for Their Bifunctional Cell-Labeling and Cytostatic Suppression Properties

    Takuya Kataoka, Sadaki Samitsu, Mitsuhiro Okuda, Daisuke Kawagoe, Motohiro Tagaya

    ACS APPLIED NANO MATERIALS   3 ( 1 ) 241 - 256  2020.01

     View Summary

    We successfully prepared hybrid nanoparticles (NPs) with photofunctional interfaces between the citric acid (Cit) molecules and europium(III) ion (Eu3+)-doped hydroxyapatite (HA) (Eu:HA) to provide bifunctional cell-labeling and cytostatic suppression. In particular, the Eu:HA NPs were synthesized in the presence of Cit, and the Cit molecules were hybridized with the Eu:HA NPs (Cit/Eu:HA). The physicochemical properties based on the interfacial Eu:HA-Cit interactions in the NPs were elucidated. The atomic structures on the Eu:HA NP surface layers were disordered by increasing the liquid-solid interfaces by the interactions between the Cit molecules and the Ca site of Eu:HA NPs. It was suggested that the Cit molecules that interacted with the Eu:HA NP surfaces sterically hindered the NP growth by the inorganic-organic interactions. Moreover, it was demonstrated that the interactions of Cit as an organic molecule and Eu:HA as an inorganic matrix were important for achieving the efficient photoluminescence properties. Thus, the efficient luminescence ability including the internal efficiency for cancer cell labeling was achieved, and simultaneously, the Cit molecular effect on the suppression of the cancer cell line growth was investigated. As a result, the luminescence enhancement with the hybridization was successfully elucidated. In particular, the low symmetry of the coordination structure for the Eu3+ ion at the Ca(I) site provided the enhanced luminescence efficiency. Furthermore, the folate N-hydroxysuccinimidyl ester (FA-NHS) was immobilized on the Cit/Eu:HA NPs to enhance the uptake efficiency of the NPs into the cancer cells. Then, the cytocompatibility and the cell-labeling property were evaluated to investigate the effect of the NPs on the cancer cell growth suppression by the Cit molecules. Cancer cell growth suppression was successfully achieved by the interactions with the Cit/Eu:HA NPs. Furthermore, the Cit/Eu:HA NPs reacted with the cells to exhibit red-color luminescence from the cells while suppressing cancer cell growth, indicating the bifunction of cell-labeling and cytostatic suppression in one particle. The hybridized Cit molecules could significantly contribute to the tumorized cell (sphere) growth suppression. In particular, the Cit/Eu:HA NPs were effectively reacted with the spheres after a culture time of 60 h, and the luminescent labeling with following the cellular shapes could be achieved 1 h after NP addition, indicating the rapid labeling process with cytostatic suppression for interacting with the spheres.

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    20
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  • Prediction and optimization of epoxy adhesive strength from a small dataset through active learning

    Sirawit Pruksawan, Guillaume Lambard, Sadaki Samitsu, Keitaro Sodeyama, Masanobu Naito

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   20 ( 1 ) 1010 - 1021  2019.12  [Refereed]  [International journal]

     View Summary

    Machine learning is emerging as a powerful tool for the discovery of novel high-performance functional materials. However, experimental datasets in the polymer-science field are typically limited and they are expensive to build. Their size (< 100 samples) limits the development of chemical intuition from experimentalists, as it constrains the use of machine-learning algorithms for extracting relevant information. We tackle this issue to predict and optimize adhesive materials by combining laboratory experimental design, an active learning pipeline and Bayesian optimization. We start from an initial dataset of 32 adhesive samples that were prepared from various molecular-weight bisphenol A-based epoxy resins and polyetheramine curing agents, mixing ratios and curing temperatures, and our data-driven method allows us to propose an optimal preparation of an adhesive material with a very high adhesive joint strength measured at 35.8???1.1?MPa after three active learning cycles (five proposed preparations per cycle). A Gradient boosting machine learning model was used for the successive prediction of the adhesive joint strength in the active learning pipeline, and the model achieved a respectable accuracy with a coefficient of determination, root mean square error and mean absolute error of 0.85, 4.0?MPa and 3.0?MPa, respectively. This study demonstrates the important impact of active learning to accelerate the design and development of tailored highly functional materials from very small datasets.

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    63
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  • Durable and Flexible Superhydrophobic Materials: Abrasion/Scratching/Slicing/Droplet Impacting/Bending/Twisting-Tolerant Composite with Porcupinefish-Like Structure

    Yoshihiro Yamauchi, Mizuki Tenjimbayashi, Sadaki Samitsu, Masanobu Naito

    ACS APPLIED MATERIALS & INTERFACES   11 ( 35 ) 32381 - 32389  2019.09  [Refereed]  [International journal]

     View Summary

    Superhydrophobic materials with micro/nanotextured surface have attracted tremendous attention owing to their potential applications such as self-cleaning, antifouling, anti-icing, and corrosion prevention. Such a micro/nanotextured surface is a key for high water repellency. However, such a texture is fragile and readily damaged when the material is deformed, scratched, or sliced off. Thus, it is challenging to develop superhydrophobic materials that can sustain high water repellency after experiencing such a mechanical deformation and damage. Here we report abrasion/ scratching/slicing/droplet impacting/bending/twisting-tolerant superhydrophobic flexible materials with porcupinefish-like structure by using a composite of micrometer-scale tetrapod-shaped ZnO and poly(dimethylsiloxane). Owing to the geometry of the tetrapod and elasticity of poly(dimethylsiloxane), the composite material exhibits stable water repellency after 1000 abrasion and 1000 bending cycles, or even after their surfaces were sliced off many times. The material maintains superhydrophobicity even under a mechanically deformed state such as bending and twisting. The materials can be painted on a variety of substrates and molded into desired shapes and used in a myriad of applications that require superhydrophobicity.

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  • Simultaneous Detection and Repair of Wetting Defects in Superhydrophobic Coatings via Cassie-Wenzel Transitions of Liquid Marbles

    Mizuki Tenjimbayashi, Sadaki Samitsu, Masanobu Naito

    ADVANCED FUNCTIONAL MATERIALS   29 ( 26 )  2019.06  [Refereed]

     View Summary

    Superhydrophobic materials that prevent unwanted liquid adhesion can easily lose this property because of limited mechanical durability despite topological/chemical control and/or robust material selection. Here, long-lasting superhydrophobic coatings with a system to effectively detect and repair damaged areas with "liquid marble," a droplet covered with hydrophobic nanoparticles, are reported. The particles prevent direct contact between the droplet and the substrate (Cassie state). However, they can adhere to the non-superhydrophobic damaged area in response to the substrate wettability via an external force or an increase in liquid volume via penetration of the outer nanoparticle layer (Wenzel state). This Cassie-Wenzel transition thus induces self-assembly of the nanoparticles onto the non-superhydrophobic area in response to the wettability, restoring superhydrophobicity.

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  • Photocatalytic nanofiber-coated alumina hollow fiber membranes for highly efficient oilfield produced water treatment

    Nur Hashimah Alias, Juhana Jaafar, Sadaki Samitsu, T. Matsuura, A. F. Ismail, M. H. D. Othman, Mukhlis A. Rahman, Nur Hidayati Othman, Norfazliana Abdullah, Syafikah Huda Paiman, N. Yusof, F. Aziz

    CHEMICAL ENGINEERING JOURNAL   360   1437 - 1446  2019.03  [Refereed]

     View Summary

    Cost-effective purification technology of oilfield produced water (OPW) is becoming a global challenge for future petroleum exploration and production industry. Energy-efficient operation of membrane separation is potentially promising. However, severe fouling problem of oil droplets demands new robust and fouling-resistant membranes with high permeability and rejection efficiency. Here, we propose a photocatalytic nanofiber-coated inorganic hollow fiber membrane suitable for OPW treatment. The membrane was fabricated by coating polyacrylonitrile (PAN) nanofiber incorporated with graphitic carbon nitride (GCN) photocatalyst on an alumina (Al2O3) hollow fiber membrane. While the highly porous coating made of smooth hydrophilic nanofibers facilitated water permeation, the coating effectively captured oil droplets in its opening, resulting in a better rejection efficiency of oil contaminants. Its sparse mesh morphology prevented oil contaminants to form dense fouling film on the membrane surface and maintained high permeate flux even after 180 min filtration. The best permeate flux of 640 L.m(-2).h(-1) and oil rejection percentage of 99% were recorded for 180 min crossflow filtration of OPW at 2 bar along with the highest pure water flux of 816 L.m(-2).h(-1). The photocatalytic activity of GCN enabled the coating to degrade the captured oil contaminants under UV irradiation, demonstrating permeate flux of 577 L.m(-2).h(-1) and oil rejection of 97% after three cycles of 180 min filtration. The excellent fouling resistance and cleaning performances of the membrane are considerably beneficial for a long-term repeated filtration operation. This work will motivate researchers to develop nanofiber-coated hollow fiber membranes for future membrane separation technology.

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  • Homogeneously Dispersed Polyrotaxane in Epoxy Adhesive and Its Improvement in the Fracture Toughness

    Sirawit Pruksawan, Sadaki Samitsu, Hideaki Yokoyama, Masanobu Naito

    MACROMOLECULES   52 ( 6 ) 2464 - 2475  2019.03  [Refereed]

     View Summary

    Polyrotaxanes (PRs), a new class of supra-molecular polymers, have recently attracted considerable attention in materials science because of their unique structure and intriguing effects on material properties. Here, we report that a PR is capable of toughening a rigid epoxy adhesive without phase separation morphology, unlike the interface-mediated toughening mechanisms established in conventional epoxy resins. A PR bearing polycaprolactone graft chains on wheel-like molecules was dispersed homogeneously in an epoxy adhesive via intermolecular hydrogen bonding. The PR-incorporating epoxy adhesive exhibited simultaneous increase in adhesive strength, fracture displacement, and fracture toughness while retaining its high glass transition temperature and tensile modulus. Morphological, thermal, and mechanical characterizations suggested that the toughening mechanism originates from the PR supramolecular structure, allowing the wheel-like molecules to rotate around and slide along the polymer main chain. The study revealed the fracture behavior of PR-containing epoxy adhesives, which may be beneficial for practical applications of network polymers.

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  • Fabrication of mesoporous nanofiber networks by phase separation–based methods

    Samitsu, S.

    Nanofiber Membranes for Medical, Environmental, and Energy Applications    2019

  • Thermo-resettable cross-linked polymers for reusable/removable adhesives

    Sandip Das, Sadaki Samitsu, Yasuyuki Nakamura, Yoshihiro Yamauchi, Debabrata Payra, Kazuaki Kato, Masanobu Naito

    POLYMER CHEMISTRY   9 ( 47 )  2018.12  [Refereed]

     View Summary

    Resettable thermosetting adhesive systems have been explored with the help of a thermo-reversible Diels-Alder (DA) reaction between a furan-bearing random copolymer and bismaleimide as a dynamic bond cross-linkage. The obtained adhesive materials exhibited good lap shear strength in the cross-linked state of up to approximate to 8 MPa. In addition, the bonding/debonding state of the adhesives could be reset by an appropriate choice of thermal treatment.

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  • Natural Polyphenol Surfactants: Solvent-Mediated Spherical Nanocontainers and Their Stimuli-Responsive Release of Molecular Payloads

    Debabrata Payra, Yoshihiro Yamauchi, Sadaki Samitsu, Masanobu Naito

    CHEMISTRY OF MATERIALS   30 ( 21 ) 8025 - 8033  2018.11  [Refereed]

     View Summary

    The self-assembly of amphiphilic building blocks represents an elegant strategy to produce (nano)structures with unique functionalities and is often investigated for a wide range of applications in biology and materials science. Herein, we report micro- to nanoscale vesicular assembly made of naturally abundant dendritic polyphenols, tannic acid (TA). Rich content in several plant parts, nontoxicity, and the inherent ability of diverse molecular interactions including H-bonding, pi-pi interactions, and metal coordination make such polyphenols a promising class of natural building blocks for supra molecular assembly and precursors for natural surfactants. The facile modification of hydrophilic TA by introducing n-alkyl chains produced TA-based multiarm surfactants, which facilitates molecular assembly in water. Systematic manipulations of processing parameters including amphiphile concentration, cosolvent ratio, and mixing rate enabled us to achieve well-defined and size-tunable spherical vesicles in the range 0.1-1.0 mu m; these were enclosed by a molecularly thin periphery of ca. 3-5 nm. Further, both hydrophilic and hydrophobic guest molecules could be encapsulated noncovalently into the vesicle, implying the presence of hydrophilic interior and hydrophobic alkyl-chain-dominated periphery in such vesicular assembly. Next, controlled disassembly of such vesicles was thoroughly examined and demonstrated high potential as nanocarriers of guest molecules. Moreover, the presence of nonsubstituted aromatic hydroxyls due to partial modification of polyphenols offered radical scavenging or antioxidant properties of the vesicles. The present report heralds a new direction of utilizing chemically modified low-cost TA as diverse supramolecular tectons, nanocarriers, and functional natural additives in a wide range of practical applications.

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    10
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  • Scattering-angle-dependent Christiansen color spectra data of poly(vinyl chloride) (PVC) suspended in styrene liquid and a comprehensive data list of wavelength-dependent refractive indices of PVC

    Sadaki Samitsu, Hideki T. Miyazaki, Hiroyo Segawa

    DATA IN BRIEF   20   1099 - 1104  2018.10  [Refereed]  [International journal]

     View Summary

    This paper reports transmission and scattering spectra of poly (vinyl chloride) (PVC) in styrene liquid, which is derived from Christiansen effect. The spectra were measured by varying scattering angles. Further discussion on Christiansen color was provided in the paper entitled "Transmitting and scattering colors of porous particles of poly(vinyl chloride) based on Christiansen effect." (Samitsu et al., 2018) [11. The paper additionally provides refractive indices of PVC reported in literatures because Christiansen effect has close relationship with wavelength-dependent refractive index, i.e. optical dispersion. The values have considerable range probably depending on samples and determination methods for refractive index. The comprehensive data list is therefore potentially useful for studying refractive index of polymers. (C) 2018 The Authors. Published by Elsevier Inc.

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  • Photocatalytic degradation of oilfield produced water using graphitic carbon nitride embedded in electrospun polyacrylonitrile nanofibers

    Nur Hashimah Alias, Juhana Jaafar, Sadaki Samitsu, Norhaniza Yusof, Mohd Hafiz Dzarfan Othman, Mukhlis A. Rahman, Ahmad Fauzi Ismail, Farhana Aziz, Wan Norharyati Wan Salleh, Nur Hidayati Othman

    CHEMOSPHERE   204   79 - 86  2018.08  [Refereed]  [International journal]

     View Summary

    Separation and purification of oilfield produced water (OPW) is a major environmental challenge due to the co-production of the OPW during petroleum exploration and production operations. Effective capture of oil contaminant and its in-situ photodegradation is one of the promising methods to purify the OPW. Based on the photocatalytic capability of graphitic carbon nitride (GCN) which was recently rediscovered, photodegradation capability of GCN for OPW was investigated in this study. GCN was synthesized by calcination of urea and further exfoliated into nanosheets. The GCNs were incorporated into polyacrylonitrile nanofibers using electrospinning, which gave a liquid-permeable self-supporting photocatalytic nanofiber mat that can be handled by hand. The photocatalytic nanofiber demonstrated 85.4% degradation of OPW under visible light irradiation, and improved the degradation to 96.6% under UV light. Effective photodegradation of the photocatalytic nanofiber for OPW originates from synergetic effects of oil adsorption by PAN nanofibers and oil photodegradation by GCNs. This study provides an insight for industrial application on purification of OPW through photocatalytic degradation under solar irradiation. (C) 2018 Elsevier Ltd. All rights reserved.

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    56
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  • Transmitting and scattering colors of porous particles of poly(vinyl chloride) based on Christiansen effect

    Sadaki Samitsu, Hideki T. Miyazaki, Hiroyo Segawa

    POLYMER   147   237 - 246  2018.07  [Refereed]

     View Summary

    Porous poly (vinyl chloride) (PVC) particles immersed in organic liquids exhibited bright colors when the refractive indices (RIs) of the liquids were close to the RI of PVC. The particles can separate white light into complementary transmitting and scattering colors. Unlike conventional structural colors resulting from interference of light, the colors, which are independent of the periodic microstructures, were systematically tuned by varying the wavelength-dependent RIs of liquids and covered the entire visible range from 320 to 780 nm. Numerical calculation based on the Mie scattering theory successfully reproduced their transmission spectra, validating the Christiansen effect of these materials. The RI determined by this effect was higher than that of the film sample and representative values in literature. The study reveals new and undiscovered RI-related features of polymers and demonstrates that the Christiansen effect will provide a simple but valuable method to study the dispersion state of polymer particles in liquids. (C) 2018 Elsevier Ltd. All rights reserved.

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    12
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  • 相分離による汎用高分子のナノ多孔化技術と応用

    佐光 貞樹

    工業材料   66 ( 3 ) 16 - 20  2018.03

     View Summary

    高分子多孔質体は、空孔・空隙がもたらす高い比表面積や表面・界面構造に裏付けされた特異な化学的、物理的性質によって、物性機能の多様性の広がりが生みだす。本稿では、微細なメソ細孔を形成する新たな相分離技術として我々が開発してきた、「急速凍結ナノ結晶化法」を紹介する。

  • Thermally Stable Mesoporous Poly(ether sulfone) Monoliths with Nanofiber Network Structures

    Sadaki Samitsu

    MACROMOLECULES   51 ( 1 ) 151 - 160  2018.01  [Refereed]

     View Summary

    The facile fabrication of mesoporous materials using commodity polymers and improvements in the thermal and mechanical stabilities of the mesopores remain challenging. Herein, we report thermally stable, mechanically robust mesoporous monoliths made of commercially available poly(ether sulfone) (PES). A PES solution dissolved in N,N-dimethylformamide spontaneously formed a physical gel upon cooling to moderate temperature and/or mixing with benzene due to partial crystallization of PES. Mesoporous monoliths obtained from this gel had a reticular structure composed of nanofibers with an average diameter of 18 nm in conjunction with a high specific surface area of 206 m(2)/g. The dense reticular structure showed a large total pore volume of 2.95 cm(3)/g, including a significant mesopore volume of 0.52 cm(3)/g. The nanofiber structure together with the high glass transition temperature of PES significantly enhanced the thermal stability of the mesopores, 80% of which were maintained even after aging at 150 degrees C for 600 h.

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    18
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  • Synthesis of silica glasses doped with SiAlON phosphors by supercritical drying

    Hiroyo Segawa, Sadaki Samitsu, Naoto Hirosaki

    INTERNATIONAL JOURNAL OF APPLIED GLASS SCIENCE   8 ( 2 ) 247 - 252  2017.06  [Refereed]

     View Summary

    Silica gels and glasses doped with SiAlON phosphors have been synthesized by the sol-gel method. Only after half a day of supercritical drying, the dried gels with many mesopores and high surface-specific area were obtained. The chromaticity of the gels can be controlled to vary widely from blue to yellow by changing the heating temperature, SiAlON concentration, and sample thickness. The thermal dependence of photoluminescence of the glass is similar to that of SiAlON powder.

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  • Be a Treasure Hunter

    佐光 貞樹

    高分子   64 ( 8 ) 503 - 503  2015.08

     View Summary

    “Research activity is like treasure hunting”, is a quote from my supervisor that was the starting point of my research career. Development of new materials for practical applications is really a tough challenge. This is a short story of how I gained scientific knowledge and learned new research techniques, and an account of what I want to become in the future.

  • Nanoprecipitation for Ultrafiltration Membranes

    Qifeng Wang, Sadaki Samitsu, Yoshihisa Fujii, Chiaki Yoshikawa, Toyohide Miyazaki, Hidekuni Banno, Izumi Ichinose

    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS   53 ( 9 ) 615 - 620  2015.05  [Refereed]

     View Summary

    Polymer nanoparticles are readily obtainable by rapidly mixing a dilute polymer solution and a poor solvent. The nanoparticles of poly(vinylphenol), poly(vinylidene fluoride), and emeraldine base polyaniline prepared by nanoprecipitation become sticky when their diameters decrease down to a few tens of nanometers, and such polymer nanoparticles spontaneously assemble into rigid fractal networks of the nanoparticles. By filtering these fibrous nanoparticle networks on a microfiltration membrane, ultrafiltration membranes with a thin free-standing filter cake layer made of nanoparticles are obtainable. The nanoparticle membranes are robust at least up to the applied pressure of 2 MPa and can separate 99% of 10 nm Au nanoparticles from the aqueous dispersion at the flux of more than 1835 L m(-2) h(-1) even at very low pressure difference of 0.08 MPa. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 615-620

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  • Hydrophilic polymer nanofibre networks for rapid removal of aromatic compounds from water

    Mohan Raj Krishnan, Sadaki Samitsu, Yoshihisa Fujii, Izumi Ichinose

    CHEMICAL COMMUNICATIONS   50 ( 66 ) 9393 - 9396  2014.08  [Refereed]  [International journal]

     View Summary

    Hydrophobic mesoporous polymer nanofibre networks were converted to hydrophilic ones by a mild sulfonation reaction. The resultant mesoporous polystyrene with a large free surface area effectively captured water-soluble dye molecules and allowed aromatic compounds to rapidly permeate into the internal binding sites.

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  • Fabrication of nanoporous engineering plastics and its application to oil adsorbents

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    日本プラスチック工業連盟誌 プラスチックス   65 ( 5 ) 68 - 72  2014.05

     View Summary

    相分離による多孔体形成技術は、高分子材料の高付加価値化のためのキーテクノロジーである。本稿では、高分子溶液の急速冷却をコアとする新たな多孔体形成技術「ナノ結晶化相分離法」と分離機能材料としての高分子メソ多孔体の可能性を紹介する。

    CiNii

  • Living supramolecular polymerization realized through a biomimetic approach

    Soichiro Ogi, Kazunori Sugiyasu, Swarup Manna, Sadaki Samitsu, Masayuki Takeuchi

    NATURE CHEMISTRY   6 ( 3 ) 188 - 195  2014.03  [Refereed]

     View Summary

    Various conventional reactions in polymer chemistry have been translated to the supramolecular domain, yet it has remained challenging to devise living supramolecular polymerization. To achieve this, self-organization occurring far from thermodynamic equilibrium-ubiquitously observed in nature-must take place. Prion infection is one example that can be observed in biological systems. Here, we present an 'artificial infection' process in which porphyrin-based monomers assemble into nanoparticles, and are then converted into nanofibres in the presence of an aliquot of the nanofibre, which acts as a 'pathogen'. We have investigated the assembly phenomenon using isodesmic and cooperative models and found that it occurs through a delicate interplay of these two aggregation pathways. Using this understanding of the mechanism taking place, we have designed a living supramolecular polymerization of the porphyrin-based monomers. Despite the fact that the polymerization is non-covalent, the reaction kinetics are analogous to that of conventional chain growth polymerization, and the supramolecular polymers were synthesized with controlled length and narrow polydispersity.

    DOI

  • Mesoporous materials created from engineering plastics

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    月刊 MATERIALSTAGE   13 ( 12 ) 67 - 70  2014.03

     View Summary

    高分子溶液の急速冷却をコアとする多孔体形成技術(ナノ結晶化相分離法)を開発し、300 m2/gを超える大きな比表面積を持った高分子メソ多孔体を製造することに成功した。高分子メソ多孔体では、直径が約10 nmのナノファイバーが無数に分岐して連結した3次元の緻密なネットワーク構造が形成されている。この特徴的なナノ構造の結果、多孔体の内部に連通したナノ細孔が形成され、液体や気体の浸透や拡散性が大幅に向上することが分かった。

    CiNii

  • Living supramolecular polymerization realized through a biomimetic approach

    Soichiro Ogi, Kazunori Sugiyasu, Swarup Manna, Sadaki Samitsu, Masayuki Takeuchi

    Nature Chemistry   6 ( 3 ) 188 - 195  2014.02  [Refereed]  [International journal]

     View Summary

    Various conventional reactions in polymer chemistry have been translated to the supramolecular domain, yet it has remained challenging to devise living supramolecular polymerization. To achieve this, self-organization occurring far from thermodynamic equilibrium-ubiquitously observed in nature-must take place. Prion infection is one example that can be observed in biological systems. Here, we present an 'artificial infection' process in which porphyrin-based monomers assemble into nanoparticles, and are then converted into nanofibres in the presence of an aliquot of the nanofibre, which acts as a 'pathogen'. We have investigated the assembly phenomenon using isodesmic and cooperative models and found that it occurs through a delicate interplay of these two aggregation pathways. Using this understanding of the mechanism taking place, we have designed a living supramolecular polymerization of the porphyrin-based monomers. Despite the fact that the polymerization is non-covalent, the reaction kinetics are analogous to that of conventional chain growth polymerization, and the supramolecular polymers were synthesized with controlled length and narrow polydispersity.

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  • Effective Surface Functionalization of Carbon Fibers for Fiber/Polymer Composites with Tailor-Made Interfaces

    Kota Shiba, Motohiro Tagaya, Sadaki Samitsu, Satoshi Motozuka

    CHEMPLUSCHEM   79 ( 2 ) 197 - 210  2014.02  [Refereed]  [International journal]

     View Summary

    Composites between carbon fibers (CFs) and heterogeneous materials have been widely studied and their fabrication techniques have been developed. However, their hydrophobic surfaces make it difficult to disperse CFs into hydrophilic resins, which results in weak junctions with ceramics. To develop high-strength composite fibers, it is important to design interfacial chemical bonds. Thus, surface-modification techniques of CFs have recently become the main focus and their interfaces have been characterized by various analytical methods. In this Minireview, various techniques that modify the CF surface by coating with inorganic polymers (metal oxide compounds) are highlighted, and the applications of novel nanocomposite fibers are also described. Furthermore, interfacial bonds between CFs and polymer resins are reviewed and discussed in terms of CF-reinforced plastics and their future prospects.

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  • Effective Surface Functionalization of Carbon Fibers for Fiber/Polymer Composites with Tailor-Made Interfaces.

    Kota Shiba, Motohiro Tagaya, Sadaki Samitsu, Satoshi Motozuka

    ChemPlusChem   79 ( 2 ) 197 - 210  2014.02  [International journal]

     View Summary

    Composites between carbon fibers (CFs) and heterogeneous materials have been widely studied and their fabrication techniques have been developed. However, their hydrophobic surfaces make it difficult to disperse CFs into hydrophilic resins, which results in weak junctions with ceramics. To develop high-strength composite fibers, it is important to design interfacial chemical bonds. Thus, surface-modification techniques of CFs have recently become the main focus and their interfaces have been characterized by various analytical methods. In this Minireview, various techniques that modify the CF surface by coating with inorganic polymers (metal oxide compounds) are highlighted, and the applications of novel nanocomposite fibers are also described. Furthermore, interfacial bonds between CFs and polymer resins are reviewed and discussed in terms of CF-reinforced plastics and their future prospects.

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    25
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  • DLC Filtration Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    NEW DIAMOND誌   30 ( 1 ) 35 - 37  2014.01  [Refereed]

     View Summary

    DLC膜は,硬度,平滑性,耐摩耗性などの機械特性だけでなく,ガスバリヤ性や抗血栓性などの優れた性質が見出されており,工作機器,飲料水ボトル,医療機器などに幅広く応用されている.本稿では,DLC膜の多孔化という視点に立ち,耐有機溶媒性のナノろ過膜としての応用について紹介した.

    CiNii

  • Ultrathin free-standing membranes from metal hydroxide nanostrands

    Santanu Karan, Qifeng Wang, Sadaki Samitsu, Yoshihisa Fujii, Izumi Ichinose

    JOURNAL OF MEMBRANE SCIENCE   448   270 - 291  2013.12  [Refereed]

     View Summary

    Under certain conditions, metal hydroxides may adopt a unique crystalline morphology known as nanostrands. These extremely fine nanofibers, no more than 2.5 nm in diameter and a few micrometers in length, form spontaneously in aqueous solutions of certain transition metal ions (Cd2+, Cu2+ and Zn2+). They typically possess a significant quantity of positive charges, a property which renders them highly dispersible in water, much like organic polyelectrolytes. Various composite fibers are obtainable from combinations of metal hydroxide nanostrands and negatively charged compounds, and these fibers may be converted into ultrathin free-standing membranes with a variety of useful applications. In addition, the nanostrands themselves can be formed into uniform nanofibrous sheet structures through a filtration process. These sheets are useful as sacrificial layers in the fabrication of free-standing polymer and nanoparticle membranes and are also stable substrates for the plasma deposition of metals and diamond-like carbon (DLC). DLC membranes exhibit surprisingly high permeation with organic solvents, and they are also expected to be useful in industry as filtration membranes for organic solvent and water contaminated with oil. This article reviews the initial work associated with the discovery of metal hydroxide nanostrands, fundamental properties and various applications to separation technology. (C) 2013 Elsevier B.V. All rights reserved.

    DOI

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  • Enhanced ethanol-gas sensing performance of Ce-doped SnO2 hollow nanofibers prepared by electrospinning

    Panneerselvam Mohanapriya, Hiroyo Segawa, Ken Watanabe, Kenji Watanabe, Sadaki Samitsu, T. S. Natarajan, N. Victor Jaya, Naoki Ohashi

    SENSORS AND ACTUATORS B-CHEMICAL   188   872 - 878  2013.11  [Refereed]

     View Summary

    Tin oxide (SnO2) hollow nanofibers doped with cerium oxide (CeOx) were synthesized to study the impact of CeO2 additives on their chemical sensing response. X-ray diffraction analysis and Raman scattering spectroscopic analysis showed that crystallization of CeO2 in the fiber composites was observed only when the Ce concentration was greater than 6 mol%. Also, maximum sensing response to ethanol was seen in the fiber composites with 6 mol% addition of Ce. Accordingly, we have discussed the possible explanations for this, including the role of crystalline CeO2 as a surface catalyst, and the role of hydrogen liberated during the dehydrogenation reaction of ethanol diffusing into the SnO2 lattice. The results obtained in this study indicate that SnO2-CeO2 nanofiber composites are potential candidates for use as high-sensitivity gas sensors. (C) 2013 Elsevier B.V. All rights reserved.

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  • Future Prospects of Porous Diamond-Like Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    膜   38 ( 5 ) 200 - 206  2013.10  [Refereed]

     View Summary

    日本膜学会からの依頼があり、多孔性ダイヤモンド状カーボン膜の将来展望について、関連する分離膜の技術動向と資源・エネルギー関連の環境保全問題を議論しながら解説した。

    DOI CiNii

  • Flash freezing route to mesoporous polymer nanofibre networks

    Sadaki Samitsu, Rui Zhang, Xinsheng Peng, Mohan Raj Krishnan, Yoshihisa Fujii, Izumi Ichinose

    NATURE COMMUNICATIONS   4 ( 1 ) 2653 - 2653  2013.10  [Refereed]  [International journal]

     View Summary

    There are increasing requirements worldwide for advanced separation materials with applications in environmental protection processes. Various mesoporous polymeric materials have been developed and they are considered as potential candidates. It is still challenging, however, to develop economically viable and durable separation materials from low-cost, mass-produced materials. Here we report the fabrication of a nanofibrous network structure from common polymers, based on a microphase separation technique from frozen polymer solutions. The resulting polymer nanofibre networks exhibit large free surface areas, exceeding 300 m(2) g(-1), as well as small pore radii as low as 1.9 nm. These mesoporous polymer materials are able to rapidly adsorb and desorb a large amount of carbon dioxide and are also capable of condensing organic vapours. Furthermore, the nanofibres made of engineering plastics with high glass transition temperatures over 200 degrees C exhibit surprisingly high, temperature-dependent adsorption of organic solvents from aqueous solution.

    DOI PubMed

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    74
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  • Effective Functionalization of Disordered Oxide Lattices on Iron Particle Surfaces Using Mechanochemical Reactions

    Satoshi Motozuka, Motohiro Tagaya, Hiroshi Nishiyama, Masami Nishikawa, Toshiyuki Ikoma, Tomohiko Yoshioka, Sadaki Samitsu, Junzo Tanaka

    JOURNAL OF PHYSICAL CHEMISTRY C   117 ( 19 ) 9908 - 9919  2013.05  [Refereed]

     View Summary

    The mechanochemical surface functionalization of iron oxides with disordered lattices on bare iron (Fe) particles was investigated using simple milling processes to clarify the formation mechanism of the oxide layer and investigate the near-surface models with different states. The homogeneous alpha-Fe particles at On bate Iron surface the milling equilibrium were first prepared under an argon atmosphere. After the subsequent milling reaction of the particles with oxygen molecules, the surface analyses by X-ray diffraction and Raman and X-ray photoelectron spectroscopies revealed that the near-surface layers consisted of two iron oxide phases (alpha-Fe2O3 and Fe3O4) through oxygen atom diffusion, and the alpha-Fe2O3. was dominantly grown on the near surface. During the initial reaction, the signals from an electron spin resonance suggested the dangling bond formation on alpha-Fe2O3. The oxygen atoms effectively induce disordered lattices in the local area to form oxidized Fe3+ clusters, and the geometric distortion formed the dangling bonds, which were theoretically supported by a molecular orbital calculation to elucidate the increase in the unpaired electron sites on the alpha-Fe2O3.,Therefore, the defective Fe3+ ions induced by the lattice mismatching between the clusters and bare alpha-Fe are found to form the disordered lattice that contains the oxygen atoms with unpaired electrons, which are successfully induced by the near-surface strain based on the simple mechanochemical reactions. The patterns of surface activation of the Fe particle surfaces by oxidization will be capable of novel chemical reactions by selective oxygen insertion as well as deep oxidation.

    DOI

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    14
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  • PB01 Gold nano particle manipulation by the interference fringe of UV laser

    Morita Tomoyuki, Tsujii Tetsuo, Samitsu Sadaki, Ishii Yoko, Takanishi Yoichi, Yamamoto Jun

    Proceedings of Japanese Liquid Crystal Society Annual meeting   2013   _PB01 - 1_-_PB01-2  2013

     View Summary

    Orientational order parameter decreases by mixing the fluorescent molecules which is bigger than nematic molecules. Thus, we can manipulate the fluorescent molecules into certain space where orientational order was decreased by photoisomerization of azobenzene. We call this operation "Molecular Manipulation." When the gold nano particles substitute for the fluorescent molecules, they gather into the higher ordered region. We try to manipulate them and make a photonic regular arrangement using the interference fringe of UV laser.

    DOI CiNii

  • Ultrafast Viscous Permeation of Organic Solvents Through Diamond-Like Carbon Nanosheets

    Santanu Karan, Sadaki Samitsu, Xinsheng Peng, Keiji Kurashima, Izumi Ichinose

    SCIENCE   335 ( 6067 ) 444 - 447  2012.01  [Refereed]  [International journal]

     View Summary

    Chemical, petrochemical, energy, and environment-related industries strongly require high-performance nanofiltration membranes applicable to organic solvents. To achieve high solvent permeability, filtration membranes must be as thin as possible, while retaining mechanical strength and solvent resistance. Here, we report on the preparation of ultrathin free-standing amorphous carbon membranes with Young's moduli of 90 to 170 gigapascals. The membranes can separate organic dyes at a rate three orders of magnitude greater than that of commercially available membranes. Permeation experiments revealed that the hard carbon layer has hydrophobic pores of similar to 1 nanometer, which allow the ultrafast viscous permeation of organic solvents through the membrane.

    DOI PubMed

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    321
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  • Conducting Polymer Electronics with Fibrillar Structure

    下村武史, 佐光 貞樹

    高分子   60 ( 7 ) 461 - 462  2011.07

     View Summary

    Conducting polymers can self-assemble into nanofibrous structure by pi-pi interaction between polymer backbones. A nematic liquid crystal solvent offers the large-scale alignment of the nanofibers. A well-organized nanofibrous structure of the conducting polymers gives high field-effect mobility irrespective of alkyl side chain length, addressing the importance of self-assembled nanostructures of polymers.

    CiNii

  • Ultrafiltration Membranes Composed of Highly Cross-Linked Cationic Polymer Gel: the Network Structure and Superior Separation Performance

    Qifeng Wang, Sadaki Samitsu, Izumi Ichinose

    ADVANCED MATERIALS   23 ( 17 ) 2004 - 2008  2011.05  [Refereed]  [International journal]

     View Summary

    Ultrafiltration membranes with a thickness of several tens of nanometers are prepared from cross-linked poly(4-vinylpyridine) gel using a flat and smooth sacrificial layer of metal hydroxide nanostrands. The membranes have a network structure with pores sizes of approximately 2.0 +/- 1.0 nm and can separate small proteins and organic dyes at a surprisingly high filtration rate.

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    40
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  • Ultrathin freestanding nanoporous membranes prepared from polystyrene nanoparticles

    Qiugen Zhang, Sandeep Ghosh, Sadaki Samitsu, Xinsheng Peng, Izumi Ichinose

    JOURNAL OF MATERIALS CHEMISTRY   21 ( 6 ) 1684 - 1688  2011  [Refereed]

     View Summary

    Freestanding cross-linked polystyrene nanoparticle membranes with a thickness of 80 nm and precisely controlled pores were prepared by filtering polystyrene nanoparticles on a microfiltration membrane by using a sacrificial layer of metal hydroxide nanostrands. The membranes could quickly separate small proteins and gold nanoparticles, showing surprisingly sharp cut-off properties.

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  • Molecular manipulator driven by spatial variation of liquid-crystalline order

    Sadaki Samitsu, Yoichi Takanishi, Jun Yamamoto

    NATURE MATERIALS   9 ( 10 ) 816 - 820  2010.10  [Refereed]  [International journal]

     View Summary

    Collective long-range interactions between micrometre-sized impurities in liquid crystals result from the elastic distortion of the liquid-crystalline order1-8. For substantially smaller polymeric impurities, what is relevant is not the elastic interaction between them but the coupling between the scalar nematic order parameter S and the polymer concentration phi. This coupling originates from local molecular interactions, but becomes long ranged because the total polymer concentration is conserved over the whole sample. Here, we propose a new mechanism by which the spatial variation of S generates a force, mediated by the coupling between S and phi, that transports nanoscale polymeric impurities. We have designed a prototype of a molecular manipulator that moves molecules along spatial variations of the scalar order parameter, modulated in a controlled manner by spot illumination of an azobenzene-doped nematic phase with ultraviolet light. We also demonstrate the use of the manipulator for the measurement of the anisotropic diffusion constant of a polymer in the nematic phase. The manipulator can control the spatial variation of the polymer concentration, thus showing promise for use in the design of hybrid soft materials.

    DOI PubMed

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  • Field-Effect Carrier Transport in Poly(3-alkylthiophene) Nanofiber Networks and Isolated Nanofibers

    Sadaki Samitsu, Takeshi Shimomura, Seiji Heike, Tomihiro Hashizume, Kohzo Ito

    MACROMOLECULES   43 ( 19 ) 7891 - 7894  2010.10  [Refereed]

     View Summary

    We report field-effect carrier transport of poly(3-alkylthiophene) nanofiber devices, focusing on the effect of the alkyl side chain length. In contrast to thin film devices reported previously, nanofiber devices with both network and single nanofiber geometry give mobilities above 0.01 cm2/Vs, little influenced by alkyl chain length. These high mobilities result from the well-organized microstructure of the nanofiber, regardless of the alkyl chain length.

    DOI

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  • Self-Assembly and One-Dimensional Alignment of a Conducting Polymer Nanofiber in a Nematic Liquid Crystal

    Sadaki Samitsu, Yoichi Takanishi, Jun Yamamoto

    MACROMOLECULES   42 ( 13 ) 4366 - 4368  2009.07  [Refereed]

     View Summary

    We have developed a whisker method using a nematic liquid crystal solvent and achieved large-scale onedimensional alignment of conducting polymer nanofibers. The polymer chains crystallized nearly one-dimensionally and self-assembled into nanofibers consisting of stacked polymers that preserved their alignment. Anisotropic crystallization in a nematic liquid crystal enabled us to obtain macroscopic alignment of conducting polymer nanofibers normal to the director. AFM images revealed several nanofibers 10 nm in height aligned normal to the director and bundled into a one-dimensional fibrillar structure 100 nm in height. The unidirectional alignment of the nanofibers enabled the emission of polarized fluorescence under illumination by unpolarized light.

    DOI

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    40
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  • Effective Production of Poly(3-alkylthiophene) Nanofibers by means of Whisker Method using Anisole Solvent: Structural, Optical, and Electrical Properties

    Sadaki Samitsu, Takeshi Shimomura, Seiji Heike, Tomihiro Hashizume, Kohzo Ito

    MACROMOLECULES   41 ( 21 ) 8000 - 8010  2008.11  [Refereed]

     View Summary

    The whisker method using anisole solvent was developed for effective production of high-aspect-ratio poly (3-alkylthiophene) (P3AT) nanofibers, and alkyl chain length dependence on nanofiber formation and their properties were fully investigated. The nanofibers have an anisotropic cross section of 3-4 nm height and 24-27 nm width, which slightly increase with the alkyl chain length, and the aspect ratio reaches 100-1000. The nanofibers consist of more than 104 parallel stacks of the extended polymer backbones along the nanofiber long axis and of 2-3 laminated layers of the polymer backbones separated by alkyl side chains. The nanofiber formation originates from quasi-one-dimensional crystallization of P3ATs induced by both an attractive pi-pi* interaction between polymer backbones and the crystallization of alkyl side chains. Carrier transport properties of a AuCl3-doped nanotiber network and single nanofibers, both of which are explained by a quasi-one-dimensional variable-range hopping (VRH) model irrespective of alkyl chain length, indicate that the origin of the random potential that localizes the carriers should be attributed not to the bridges between nanotibers but to some factor involved in a single nanofiber.

    DOI

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  • Synthesis of a molecular tube in dimethyl sulfoxide and its inclusion complexation behavior with poly(ethylene oxide-ran-propylene oxide)

    Sadaki Samitsu, Jun Araki, Takeshi Shimomura, Kohzo Ito

    MACROMOLECULES   41 ( 14 ) 5385 - 5392  2008.07  [Refereed]

     View Summary

    A molecular tube was synthesized by cross-linking alpha-cyclodextrins (alpha-CDs) of a polyrotaxane with epichlorohydrin in dimethyl sulfoxide (DMSO). The obtained molecular tube was characterized with H-1 and C-13 NMR, size-exclusion chromatography, and UV-vis absorption titration with iodine. The use of DMSO afforded greater cross-linking efficiency than that with the conventional aqueous NaOH. The inclusion-dissociation behavior of the molecular tube and alpha-CD with poly[(ethylene oxide)-ran-(propylene oxide)] (PEOrPO) having a central azobenzene moiety was investigated using induced circular dichroism measurements. The PEOrPO with azobenzene was included in the tube cavity, resulting in the exhibition of induced circular dichroism. This result suggests the stable inclusion of propyrene oxide units with a molecular tube for the first time. Higher temperature and higher molecular weight of PEOrPO yielded lesser amounts of the inclusion complexes with the molecular tube. The enthalpy change of inclusion complexation of the molecular tube with the PEOrPO-Az was calculated to be -3.6 kJ mol(-1) per PO unit, which is similar to that with a linear alkyl chain.

    DOI

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    11
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  • Nanofiber preparation by whisker method using solvent-soluble conducting polymers

    Sadaki Samitsu, Takeshi Shimomura, Kohzo Ito

    THIN SOLID FILMS   516 ( 9 ) 2478 - 2486  2008.03  [Refereed]

     View Summary

    We prepared conducting polymer nanofibers by means of whisker formation in a solution by using solvent-soluble conducting polymers with alkyl or alkoxy side chains. A morphological characterization using an atomic force microscope indicated that they have one-dimensional nanofibrillar structures with typical heights of 3-10 nm. The conductivity of a single poly(3-hexylthiophene) (P3HT) nanofiber was measured using 300-nm-spacing Pt electrodes and the conductivity of 0.25 S/cm at 290 K was achieved by chemical doping using nitrosoniurn tetrafluoroborate. Considering the temperature dependence of the conductivity, the carrier transport in the single nanofiber was explained by a quasi-one-dimensional variable range-hopping model. (c) 2007 Elsevier B.V All rights reserved.

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  • New solvent for polyrotaxane. II. Dissolution behavior of polyrotaxane in ionic liquids and preparation of ionic liquid-containing slide-ring gels

    Sadaki Samitsu, Jun Araki, Toshiyuki Kataoka, Kohzo Ito

    JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS   44 ( 14 ) 1985 - 1994  2006.07  [Refereed]

     View Summary

    The dissolution behavior of polyrotaxanes, consisting of a-cyclodextrin and poly(ethylene glycol), with different molecular weights (2000 and 35,000) was investigated. Halogen-containing ionic liquids, such as chlorides or bromides, were found to be good solvents for polyrotaxanes, regardless of their cations. Dissolution required a high temperature (above 90 degrees C), while intensive heating over 105 degrees C seemed to cause decomposition of the polyrotaxane. The discovery of new solvents for polyrotaxane was applied in the preparation of ionic liquid-containing slide-ring gels (SR gels), that is supramolecular networks of polyrotaxane swollen with ionic liquids, using a devised "non-drying" technique accompanied by solvent exchange. Significant swelling of the SR gels with the ionic liquids was confirmed by dynamic mechanical measurements. (c) 2006 Wiley Periodicals, Inc.

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  • Conducting Nanofiber

    SHIMOMURA Takeshi, SAMITSU Sadaki

    Kobunshi   55 ( 3 ) 134 - 137  2006.03

    DOI CiNii

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Books and Other Publications

  • ナノファイバーの製造・加工技術と応用事例

    Sadaki Samitsu( Part: Contributor, 第6章第1節 相分離法によるメソ多孔性の高分子ナノファイバーネットワークの製造 pp.149-159)

    Technical Information Institute co. ltd  2019.10 ISBN: 9784861047657

  • Nanofiber Membranes for Medical, Environmental, and Energy Applications

    Sadaki Samitsu( Part: Contributor, 13.Fabrication of Mesoporous Nanofiber Networks by Phase Separation-Based Methods pp.274-289)

    CRC Press  2019.08 ISBN: 9780815387039

  • 多孔質フィルム/膜の製造技術

    Sadaki Samitsu( Part: Contributor, 第1章第2節ナノ結晶化相分離法による高分子メソ多孔体の作製. pp.13-32)

    S&T Publishing  2016.06 ISBN: 9784907002565

  • 粉体・微粒子分析テクニック事例集

    Sadaki Samitsu( Part: Contributor, 第1章第2節 マイクロ・ナノ粒子のガス吸着法による比表面積評価 pp.30-31)

    Technical Information Institute co. ltd  2015.11 ISBN: 9784861046049

  • PEDOTの材料物性とデバイス応用

    下村 武史, 佐光 貞樹, 伊藤 耕三( Part: Contributor, 第6章9節 PEDOTナノファイバー pp.370-374)

    S&T Publishing  2012.03 ISBN: 9784864280389

     View Summary

    分子コーミング法を用いて作製したPEDOT / PSSナノファイバー1本の導電率測定に取り組んだ。PEDOT/PSS水溶液の入ったシリンジを制御し、微小電極端子にかかるように電極基板上に水滴を滴下した後、ゆっくり吸い上げることで、電極上にPEDOT/PSSナノファイバーを作製した。AFM技術を適用することで、ナノファイバー1本の導電性を評価することができる。微小電極端子間にかかる3本のPEDOT/PSSナノファイバーをAFMの探針を押し当てて順番に1本ずつ切断し、それぞれのPEDOT/PSSナノファイバー切断前後での電流電圧特性の変化から、切断したナノファイバーの導電率を見積もった。

Presentations

  • Porous structure fabrication of commercially-available polymers and their applications

    Sadaki Samitsu  [Invited]

    Presentation date: 2020.10

  • Fabrication of porous polymers and their structural analysis

    Sadaki Samitsu  [Invited]

    Presentation date: 2020.10

  • 高分子材料のナノ多孔化技術と構造解析~高付加価値をめざすこれからのプロセスと細孔評価技術~

    Sadaki Samitsu  [Invited]

    Presentation date: 2019.04

  • 相分離法によるメソ多孔性の高分子ナノファイバーネットワークの製造

    Sadaki Samitsu  [Invited]

    Presentation date: 2019.04

  • Phase separation-based fabrication methods of nanoporous commodity polymers and their applications

    佐光 貞樹

    高分子同友会勉強会 

    Presentation date: 2018.09

     View Summary

    微多孔質高分子は、セパレーター・分離膜・吸着材・緩衝材といった付加価値の高い製品になる。素材・形状・用途によって多彩な手法が活用されているが、簡便・低コストで適用範囲が広い相分離は工業プロセスの主流である。本講演では、汎用高分子の相分離を用いたナノ多孔化技術の最新動向と展望について紹介する。

  • Homogeneously Dispersed Polyrotaxane in Epoxy Adhesive and Its Improvement in the Fracture Toughness

    プルクサワン シラウィット, 佐光 貞樹, 内藤 昌信

    Tsukuba Global Science Week 2018 

    Presentation date: 2018.09

     View Summary

    Epoxy adhesives are one of the indispensable materials for construction of airplanes and automobiles due to their strong adhesive properties, high thermal and chemical stability. However, their lower fracture toughness often involves brittle fracture under practical conditions, which limits its practical application severely. Conventionally, molecular modifiers, such as liquid plasticizers or rubbery polymers, were incorporated in epoxy adhesives, which provide flexibility to a rigid epoxy polymer network. However, the adhesive strength and/or thermal stability are often sacrificed. The lower thermal stability also leads to a degradation in adhesive performance at high temperature.To overcome this obstacle, we developed an epoxy adhesive modified with polyrotaxane (PR), which enables us t

  • Transmitting and scattering colors of porous particles of poly(vinyl chloride) based on Christiansen effect

    佐光 貞樹, 宮崎 英樹, 瀬川 浩代

    第67回高分子討論会 

    Presentation date: 2018.09

     View Summary

    多孔質の塩化ビニルの粉体に屈折率の近いスチレンモノマーを含浸させるとオレンジ色に発色することを見出した。この発色現象は、傾きの異なる屈折率の波長分散が特定の波長で交差するために生じ、クリスチャンセン効果で説明できる。

  • Structural colorization of poly(vinyl chloride) powder

    佐光 貞樹

    近畿化学協会 2018年度第1回 重合工学部会 

    Presentation date: 2018.06

     View Summary

    光の吸収によらず、屈折率の空間変化によって生じる呈色現象は構造色と呼ばれる。構造色は色素や顔料による着色とは異なる色彩を表し、新しい応用利用が検討されている。本研究では、多孔質のポリ塩化ビニル粉末が特定の液体を吸収することで構造色が現れることを見出した。本発表では、この透過性のある構造色の発色原理と応用可能性を説明する。

  • Solvent-induced crystallization of polymers

    佐光 貞樹

    つくばソフトマター2018 

    Presentation date: 2018.06

     View Summary

    高分子の結晶化機構は、材料強度や耐熱性を向上させるための重要な因子である。工業的に用いられている高分子のうちで結晶性を示すものは未だ限られており、結晶性を制御するために高分子の結晶化機構をさらに深く理解し自在に制御する方法論を検討する必要がある。本研究では、溶媒分子によって誘起される高分子の結晶化機構を検討した例を発表する。

  • A thermally-stable mesoporous monolith made of engineering plastics

    佐光 貞樹

    第67回高分子学会年次大会 

    Presentation date: 2018.05

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    We report thermally-stable, mechanically-robust mesoporous monoliths made of commercially-available poly(ether sulfone) (PES). A PES solution dissolved in N,N-dimethylformamide spontaneously formed a physical gel upon cooling to moderate temperature and/or mixing with benzene due to partial crystallization of PES. Mesoporous monoliths obtained from this gel had a reticular structure composed of nanofibers with an average diameter of 18 nm. The dense reticular structure showed a significant mesopore volume of 0.52 cm3/g. The nanofiber structure together with the high glass transition temperature of PES significantly enhanced the thermal stability of the mesopores, 80% of which were maintained even after aging at 150 。&#65533;C for 600 hours.

  • Flash-freezing Nanocrystallization as a Fabrication Method of Mesoporous Polymers

    SAMITSU, Sadaki

    NIMS WEEK 2017 

    Presentation date: 2017.10

     View Summary

    Here we report new type of phase separation in a polymer solution: nanocrystallization phase separation. We found that flash freezing of a high-concentration polymer solution results in the uniform bicontinuous microstructure of solvent nanocrystals and nanofibrous polymer networks. Since the solvent nanocrystals act as a uniform template of nanopores, solvent extraction by an excess poor solvent successfully gave mesoporous polymers with large specific surface areas as well as sharp pore size distributions in 5 to 20 nanometer size.

  • Improvement of Adhesive Strength and Ductility of Epoxy Resin Modified with Polyrotaxane

    プルクサワン シラウィット, 佐光 貞樹, 内藤 昌信

    NIMS WEEK 2017 

    Presentation date: 2017.10

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    Epoxy-based adhesives are one of the indispensable materials for construction of airplanes and automobiles due to their strong adhesive properties. However, the main limitations of epoxy-based adhesives are their low fracture toughness and they are easy to fracture with thermal stress. Conventionally, incorporation of rubber modifiers in epoxy-based resins has been a material design strategy to toughen the epoxy&#8211;based adhesives. However, addition of the rubber modifiers significantly reduces strength, modulus, and glass transition temperature of the adhesives. To overcome this obstacle, PR with polycaprolactone graft chains on the ring molecules was incorporated into conventional epoxy-based adhesive to improve adhesive properties. We found that the PR showed good miscibility in ep

  • Improvement of Adhesive Strength and Ductility of Epoxy Resin Modified with Polyrotaxane

    プルクサワン シラウィット, 佐光 貞樹, 内藤 昌信

    Tsukuba Global Science Week 2017 

    Presentation date: 2017.09

     View Summary

    Epoxy-based adhesives are one of the indispensable materials for construction of airplanes and automobiles due to their strong adhesive properties, high thermal and chemical stability. However, the main limitations of epoxy-based adhesives are their low fracture toughness and they are easy to fracture with thermal stress. Conventionally, incorporation of rubber modifiers in epoxy-based resins has been a material design strategy to toughen the epoxy&#8211;based adhesives. However, addition of the rubber modifiers significantly reduces strength, modulus, and glass transition temperature of the epoxy-based adhesives.To overcome this obstacle, we developed an epoxy-based adhesive modified with polyrotaxane (PR). PR is a new class of polymer, which consists with a linear polymer and ring molec

  • Mesoporous polymers fabricated with phase separation of commodity polymers

    佐光 貞樹

    17-3ポリマーフロンティア21 

    Presentation date: 2017.09

     View Summary

    汎用高分子の多孔化技術は高付加価値製品の作製法として工業的に利用されている。本発表では、急速凍結ナノ結晶化法という新しい相分離技術と、それによって実現される汎用高分子メソ多孔体の特性と機能を紹介する。

  • Separation functional materials realized with new fabrication methodologies of nanoporous polymers

    佐光 貞樹

    第63回高分子研究発表会 

    Presentation date: 2017.07

     View Summary

    ナノメートルサイズの細孔を有する高分子多孔体は、分離技術の高効率化を実現するキーマテリアルである。分子選択的な物質透過や優れた吸着特性により水処理膜・ガスフィルター・吸着材に利用される。本発表では高分子材料における微細孔の形成機構を探究し開発した新たなナノ多孔化技術を紹介する。

  • Mesoporous polymers fabricated with phase separation method and their separation applications

    佐光 貞樹

    第66回高分子学会年次大会 

    Presentation date: 2017.05

     View Summary

    本発表では、微細なメソ細孔を形成する新たな相分離技術として、我々が開発した「急速凍結ナノ結晶化法」を紹介する。この手法では、汎用高分子の溶液を急冷して低温で溶媒分子を結晶化させるだけでメソ細孔を試料全体に形成することができる。この手法はテンプレートを用いない簡便な工程でスケールアップに適している。結晶化というロバストな動作原理に基づくので多様な系への拡張も期待できる。3次元の連通メソ細孔と200 m2/gを超える大きな比表面積を持つメソ多孔体は分離機能材料として有望である。

  • Solvent crystallization and phase separation behavior in polymer solutions

    佐光 貞樹

    つくばソフトマター研究会2017 

    Presentation date: 2017.05

     View Summary

    高分子溶液中での溶媒分子の結晶化挙動に関する研究例はあまり多くない。我々は、急速凍結過程により溶媒分子の結晶化挙動を制御して高分子メソ多孔体を形成する手法を報告してきた。本研究では、高分子溶液中での溶媒分子の結晶化挙動を基礎科学的に考察した結果と今後の展望を発表する。

  • Nanocrystallization phase separation: new route for mesoporous polymers

    SAMITSU, Sadaki

    NU-NIMS Materials Genome Workshop 

    Presentation date: 2017.03

     View Summary

    We will present recent progress on fabrication of mesoporous polymers using phase separation method. In particular, we will focus on our new concept of nanoporous polymer fabrication based on flash freezing nanocrystallization method.

  • Fabrication and applications of nanoporous polymers using phase separation method - to focus on nanocrystal-templated method

    佐光 貞樹

    高分子・フィルム多孔化技術の基礎から応用まで 

    Presentation date: 2017.02

     View Summary

    相分離現象は高分子膜・多孔体の作製法として広く利用されています。本講演では、多孔化技術における相分離の活用例を紹介し、特に講演者が開発したナノ結晶化相分離法を中心に解説します。独自の着眼点により溶媒結晶サイズを劇的に微細化し、簡便な工程で汎用高分子のナノ多孔化を実現することができます。

  • Sub-Nanoporous Carbon Thin Films Grown by Plasma-Enhanced Chemical Vapor Deposition Method

    SAMITSU, Sadaki, ICHINOSE, Izumi

    2016 MRS Fall Meeting 

    Presentation date: 2016.11

     View Summary

    A sub-nanoporous carbon thin film has been considered as a promising candidate for a next- generation robust reverse osmosis (RO) membrane. We focused on fabrication of carbon thin films using plasma-enhanced chemical vapor deposition (PECVD) method. Here we present how we can introduce sub-nanometer pores in a carbon thin film and control its size and porosity by tuning plasma parameters.

  • Structural color of poly(vinyl chloride) powders

    佐光 貞樹

    第65回高分子討論会 

    Presentation date: 2016.09

     View Summary

    市販ポリ塩化ビニルのパウダーを汎用溶媒に浸漬することで、屈折率を適切に選択することにより構造発色を発現できることを見出した。構造発色の要因を明らかにする。

  • Plasma-enhanced chemical vapor deposition for fabrication of carbon-based reverse osmosis membranes

    佐光 貞樹, 一ノ瀬 泉

    第65回高分子討論会 

    Presentation date: 2016.09

     View Summary

    カーボン薄膜にサブナノ孔を形成するためのプラズマ励起CVD法と作製した親水性カーボン逆浸透膜の分離特性について報告する。

  • Composition and Temperature Sensitive Conducting Gel

    ゴスワミ レッカ, 樋口 倫太郎, 新ヶ谷 義隆, 佐光 貞樹, 中山 知信

    JSAP Autumn Meeting 

    Presentation date: 2016.09

     View Summary

    A viscoelastic gel is formed in a surfactant and doped polyaniline mixture. An incorporation of doped polyaniline enhances the rheological properties like viscosity, elasticity and relaxation time of surfactant mixtures as confirmed by rheological measurements. The rheological property of viscoelastic gel with and without polyaniline is dependent on concentration of components, temperature. Additionally, polyaniline-incorporated viscoelastic gel shows interesting conducting properties. Measurements show that the conductivity is sensitive to temperature, concentration of components.

  • New concepts on creating nanopores: mesoporous polymers and carbon-based reverse-osmosis membranes

    SAMITSU, Sadaki

    Japan-Taiwan Joint Seminar EEYC 2016 

    Presentation date: 2016.06

     View Summary

    Nanoporous polymers have been industrially used in valuable products such as large-scale separator sheet of Li-ion batteries, hollow fiber membranes for medical usage, and high-performance membrane and adsorbent for gas and water purification. New development of fabrication methodology of nanoporous polymers is therefore a key challenge that will make it possible to launch new applications. Here we will present new concepts of nanoporous polymer fabrication. One is phase separation method using nanocrystallization of solvent molecules, which provides mesoporous polymers of commodity polymers. The other is precisely-controlled plasma-enhanced chemical vapor deposition method by which we could fabricate hydrophilic carbon-based reverse-osmosis membranes for water desalination.

  • Hydrophilic Carbon-based Reverse Osmosis Membranes fabricated with Plasma-Enhanced Chemical Vapor Deposition Method

    佐光 貞樹, 一ノ瀬 泉

    第65回 高分子学会年次大会 

    Presentation date: 2016.05

     View Summary

    プラズマ励起化学蒸着法でモノマーを重合し、カーボン骨格を持つサブナノ多孔性の逆浸透膜を作製する。カーボン逆浸透膜の化学構造、細孔構造、力学特性、透過特性を多角的に評価した結果を発表する。

  • Separation Properties of Nitrogen-containing Hydrophilic Carbon-based Reverse Osmosis Membranes Prepared by Using Amine Monomer

    佐光 貞樹, 一ノ瀬 泉

    第65回 高分子学会年次大会 

    Presentation date: 2016.05

     View Summary

    本発表では、分子構造の異なるアミンモノマーを用いてPECVD法によるカーボン逆浸透膜の作製検討を行ない、モノマーの分子構造と得られた逆浸透膜の分離特性の関係について報告する。

  • Carbon-based Reverse Osmosis Membranes Prepared by Plasma-Enhanced Chemical Vapor Deposition Method

    佐光 貞樹, 一ノ瀬 泉

    アクア・イノベーション拠点(COI) 第3回シンポジウム 

    Presentation date: 2016.02

     View Summary

    アクアCOI拠点事業に参画して進めてきたカーボン逆浸透膜の研究開発の成果をポスター発表で報告する。カーボン逆浸透膜の基本プロトコルの確立し、プラズマCVD法の成膜条件を検討してカーボン薄膜内のサブナノ孔の形成、カーボン逆浸透膜の組成制御と薄膜化を行なうことで性能向上を実現し、フェーズI目標値(透過流束2.5L/m2h、MgCl2阻止率90%以上かつNaCl阻止率50%以上)を達成した。

  • Flash freezing method for mesoporous polymer fabrication

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    第24回ポリマー材料フォーラム 

    Presentation date: 2015.11

     View Summary

    高分子の濃厚溶液を急速凍結した後、低温で冷結晶化することで、高分子メソ多孔体を作製する手法を報告する。得られた高分子メソ多孔体の機能材料応用に関する研究成果も合わせて発表する。

  • Reverse Osmosis Membranes Prepared by Plasma-Enhanced Chemical Vapor Deposition Method

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    第64回高分子討論会 

    Presentation date: 2015.09

     View Summary

    Reverse osmosis membranes were prepared on porous polymer supports using a plasma-enhanced CVD method. The membranes showed high salt rejection of more than 95 % for both aqueous solutions of magnesium chloride and sodium chloride. Pore size distribution of the membrane was evaluated by a positron annihilation life time measurement. Average radius of the pore size distribution was larger than that of water molecule and smaller than that of hydrated sodium ion.

  • Fabrication Methodology of Mesoporous Polymers Using Nanocrystallization Phase Separation

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    第64回高分子討論会 

    Presentation date: 2015.09

     View Summary

    Mesoporous polymer materials were prepared by using nanocrystallization phase separation method. In the method, a high-concentration polymer solution is rapidly frozen through a flash freezing route and then cold crystallization of solvent molecules occurs at a low temperature. Solvent extraction gives mesoporous polymers, which is useful for advanced liquid and gas separation applications.

  • 3D-TEM of a Newly Developed Polysulfone Nanoporous Polymer

    HASEGAWA, Akira, SAMITSU, Sadaki, ICHINOSE, Izumi

    NIMS Conference 2015 

    Presentation date: 2015.07

     View Summary

    A nanoporous polysulfone material has been developed recently, which featured with superior separation properties. 3D TEM was carried out to characterize the material. TEM specimens were prepared with a cryo-ultra-microtome after the piece was embedded in resin, or cut with a cryo-FIB directly without embedding. The TEM observation was carried out with a TEM, JEM-2100F. The nanopores were confirmed to be interconnected randomly in the polymer with tomogram and 3D visualization. The ratios of pore to mass and surface to mass were analyzed quantitatively from the slice images of the tomogram. They agreed closely with those obtained from gas absorption measurements.

  • Quantitative Analysis of a Newly Developed Polysulfone Nanoporous Polymer by Transmission Electron Microcopy Tomography

    HASEGAWA, Akira, SAMITSU, Sadaki, ICHINOSE, Izumi

    2015 International Conference on Nanospace Materials 

    Presentation date: 2015.06

     View Summary

    We fabricated nanoporous polymers with an interconnected fiber network structure.1,2 Confirmation of the internal fiber network structure is very important in point of view of application. The present work aims to quantitatively evaluate the porosity of the materials, the connection of nanopores, and the specific surface by means of 3-dimensional (3D) transmission electron microscopy (TEM) in order to understand the superior performance of these materials.The nanopores were confirmed to be interconnected randomly in the polymer with tomogram and 3D visualization. The ratios of pore to mass and surface to mass were analyzed quantitatively from the slice images of the tomogram. They agreed closely with those obtained from gas absorption measurements.

  • Separation Properties of Nanoporous Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    平成27年度繊維学会年次大会 

    Presentation date: 2015.06

     View Summary

    化学的に安定なダイヤモンド状カーボン(DLC)超薄膜に着目し、ナノ細孔を有する超薄膜の分離特性について検討した結果について紹介する。

  • Nanocrystallization phase separation: fabrication methodology of mesoporous polymers

    SAMITSU, Sadaki, FUJII, Yoshihisa, ICHINOSE, Izumi

    Frontiers in Polymer Science 2015 

    Presentation date: 2015.05

     View Summary

    Here we report new type of phase separation in a polymer solution: nanocrystallization phase separation. We found that flash freezing of a high-concentration polymer solution results in the uniform bicontinuous microstructure of solvent nanocrystals and nanofibrous polymer networks.

  • Separation Properties of Porous Diamond-Like Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    平成26年度東北地区先端高分子セミナー 

    Presentation date: 2015.03

     View Summary

    化学的にも熱的も安定なカーボン膜に着目し、ロバストなろ過フィルターとしての応用を目指している。本研究では、多孔性ダイヤモンド状カーボン膜の分離特性と力学特性について検討した。

  • Mesoporous polymers for gas and liquid separation applications

    SAMITSU, Sadaki, FUJII, Yoshihisa, ICHINOSE, Izumi

    Hybrid Materials 2015 

    Presentation date: 2015.03

     View Summary

    Well-defined nanoscale channels formed by the network of mesopores make possible selective permeation and superior adsorption, and therefore, mesoporous polymers processed in the form of membranes and adsorbents are very useful for advanced separation technologies. Here we report new type of phase separation in a polymer solution: nanocrystallization phase separation. We found that flash freezing of a high-concentration polymer solution results in the uniform bicontinuous microstructure of solvent nanocrystals and nanofibrous polymer networks.

  • Nanocrystallization Phase Separation: New Route on Fabrication Methodology of Mesoporous Polymers

    SAMITSU, Sadaki, KRISHNAN, Mohan Raj, FUJII, Yoshihisa, ICHINOSE, Izumi

    The 10th SPSJ International Polymer Conference (IPC2014) 

    Presentation date: 2014.12

     View Summary

    Phase separation of polymer solutions has been industrially used to fabricate porous polymer materials (membranes and absorbents). Despite the long-term history over 50 years, direct fabrication of mesopores without block-copolymer is still challenging. Here we propose a novel mechanism of phase separation in polymer solutions, which is related to crystallization of solvent molecules. Dispersed polymer chains significantly disturb the crystallization of the solvent molecules and therefore reduce the crystal size of the solvent molecules to be down to ten nanometers or so. Based on this concept, we have successfully fabricated mesoporous polymers consisting of three-dimensional network of ultrafine polymer nanofibers.

  • Nanoporous Carbon Membranes for the Purification of Oil-Contaminated Water

    FUJII, Yoshihisa, SAMITSU, Sadaki, ICHINOSE, Izumi

    2014 MRS Fall Meeting & Exhibit 

    Presentation date: 2014.11

     View Summary

    It is not easy to solve the ongoing issues of worldwide environmental pollution. In both the chemical and petrochemical industries, the nanofiltration of organic solvents may make a significant contribution to improved energy efficiency in the production process. Polymer-based membranes are widely used for gas separation, filtration, desalination of seawater, wastewater treatment, etc. Chemical, petrochemical, energy and environment-related industries, however, strongly require highly durable membranes applicable under extreme conditions, since the present polymeric membranes gradually or sometimes rapidly deteriorate with time due to undesired swelling, clogging, and chemical reactions. In our poster presentation, new porous diamond-like carbon (DLC) membranes will be discussed.

  • Mechanical Properties of Nano Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    第62回レオロジー討論会 

    Presentation date: 2014.10

     View Summary

    ナノカーボン膜の力学特性が及ぼす表面形態について議論する

  • Mesoporous Nanofiber Networks of Nanoparticle/Polymer Hybrids

    佐光 貞樹, クリスナン モハン ラジ, 藤井 義久, 一ノ瀬 泉

    第63回高分子討論会 

    Presentation date: 2014.09

     View Summary

    本発表では、ナノ結晶化相分離法を、ナノ粒子を添加した高分子複合系に拡張し、無機/有機ハイブリッド型高分子メソ多孔体の創製を試みた。

  • 複相ガラス中のナノ構造形成 に関するシミュレーション解析

    下野 昌人, 佐光 貞樹, 小野寺 秀博

    日本金属学会2014年秋期大会 

    Presentation date: 2014.09

     View Summary

    ポーラス材料の表面積を増やして特性を高めるために、急冷凝固および加熱処理によって起こる自発的なナノ構造形成を活かす手法が注目されている。構造形成のメカニズムを理解するために、お互いに強く結合する溶質元素ABをそれらと弱い結合を持つ溶媒元素Cに溶解させた擬二元型モデルに対し、液相からの急冷凝固およびガラス相からの加熱など種々の熱処理に対してMDシミュレーションを実施し、生成した凝固組織の幾何学的特徴を比較することでナノ構造形成制御のための指導原理を探る。

  • Separation Properties of Nanoporous Thin Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    第63回高分子討論会 

    Presentation date: 2014.09

     View Summary

    The solvent&#8211;resistant nanofiltration membranes with superior permeability characteristics could be very attractive for various applications such as oily wastewater purifications, but existing solvent&#8211;resistant nanofiltration membranes tend to have very low permeability due to the large thickness of separation function layer. In this study, we prepared the nanoporous carbon membranes on the basis of porous diamond-like carbon (DLC) deposition technique.

  • Nanocrystallization Phase Separation - Kinetics on Solid-Liquid Phase Separation of Polymer Solutions

    佐光 貞樹

    第13回 関東ソフトマター研究会 

    Presentation date: 2014.08

     View Summary

    高分子溶液の固液相分離現象を研究した。急速冷却過程を使用すると、溶液中で溶媒分子がナノスケールの結晶を形成し、溶媒分子のナノ結晶相と高分子の濃厚相に相分離することを見出した。

  • Fabrication of Mesoporous Polymer Nanofibre Network: Functionalization and Their Application in Removal of Aromatic Compounds from Water

    KRISHNAN, Mohan Raj, SAMITSU, Sadaki, FUJII, Yoshihisa, ICHINOSE, Izumi

    NIMS Conference 2014 

    Presentation date: 2014.07

     View Summary

    Recently, we have reported a flash freezing route to the fabrication of mesoporous polymer nanofibre networks by modified phase separation technique1. This method is based on nano-crystallization of solvent molecules under deep frozen conditions and subsequent spatially restricted phase separation. The specific surface area of mesoporous polystyrene nanofibre network fabricated by this modified phase separation technique is exceeding to 300m2/g with the average fiber diameter of 16nm. The resulting mesoporous polymers with large free surface areas would be ideal adsorbents for oil-contaminated water if the pores are converted to partially hydrophilic by controlled chemical functionalization. The controlled sulfonation of inner surfaces of the polystyrene mesopores and significant adsorptio

  • Mechanical Properties of Nanoporous Thin Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    平成26年度繊維学会年次大会 

    Presentation date: 2014.06

     View Summary

    化学的に安定なダイヤモンド状カーボン(DLC)超薄膜に着目し、ナノ細孔を有する超薄膜の力学物性について検討した結果について紹介する。

  • Fabrication of mesoporous polymer materials with the nanocrystallization of solvent molecules and their applications

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    平成26年度繊維学会年次大会 

    Presentation date: 2014.06

     View Summary

    高分子の濃厚溶液を急冷した時に、低温でナノ結晶化した溶媒相と高分子相にミクロ相分離が形成することを見出した。この発見を利用した、汎用高分子のメソ多孔体作製技術と多孔体の応用例を発表する。

  • Thermal Properties of Nanoporous Thin Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    第63回高分子学会年次大会 

    Presentation date: 2014.05

     View Summary

    化学的に安定なダイヤモンド状カーボン(DLC)を用いて作製したナノ細孔を有するカーボン超薄膜の熱物性について紹介する。

  • Solvent effect on pore size control of mesoporous polymer nanofiber networks

    佐光 貞樹, クリスナン モハン ラジ, 藤井 義久, 一ノ瀬 泉

    第63回高分子学会年次大会 

    Presentation date: 2014.05

     View Summary

    高分子溶液を急冷することで、高分子メソ多孔体を作製する手法に関する研究発表を行なう。特に本発表では、使用する溶媒分子の種類が得られる高分子多孔体の細孔サイズに与える効果について報告する。

  • Oil adsorbents of mesoporous polymers

    佐光 貞樹, 藤井 義久, 一ノ瀬 泉

    第3回 JACI/GSCシンポジウム 

    Presentation date: 2014.05

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    高分子溶液の急速冷却をコアとする多孔体形成技術(ナノ結晶化相分離法)を開発し、大きな比表面積を持った高分子メソ多孔体を製造することに成功した。高分子メソ多孔体は、水中に溶解したオイル分子に対して優れた分離性能を示す。

  • ダイヤモンド状カーボンでできた高性能ろ過フィルター

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    「ナノ界面技術の基盤構築」第3回公開シンポジウム 

    Presentation date: 2013.12

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    ダイヤモンド状カーボン膜を介した液体の透過挙動に関してポスター発表を行う。合わせて、高分子メソ多孔体の展示を行う。

  • Fabrication of Mesoporous Polymer Materials through Solvent Nano-crystallization

    SAMITSU, Sadaki, ICHINOSE, Izumi

    The 15th International Conference on Biomedical Engineering 

    Presentation date: 2013.12

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    Here we propose a novel mechanism of phase separation in polymer solutions, which is related to crystallization of solvent molecules. Dispersed polymer chains significantly disturb the crystallization of the solvent molecules and therefore reduce the crystal size of the solvent molecules to be down to ten nanometers or so. Based on this concept, we have successfully fabricated mesoporous polymers consisting of three-dimensional network of ultrafine polymer nanofibers.

  • Porous Diamond-Like Carbon Membranes

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    第11回環境研究シンポジウム 

    Presentation date: 2013.11

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    耐有機溶媒性のろ過フィルターは、オイルサンド開発における排水処理、化学工業における溶媒の再利用、あるいはRO膜のプレフィルターとして期待されている。化学的に安定な高性能ろ過フィルターを開発することで、酸やアルカリ、有機溶媒を含んだ汚染水の効率的な浄化が可能となる。

  • Porous Diamond-Like Carbon Membranes

    FUJII, Yoshihisa, SAMITSU, Sadaki, ICHINOSE, Izumi

    第13回 NIMSフォーラム 

    Presentation date: 2013.10

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    化学的に安定かつ、極薄になっても十分な力学的強度をもつ材料として、ダイヤモンド状カーボン(Diamond-Like Carbon, DLC)を選択し、その製膜条件を探索する過程で、サブナノメートルの細孔を介して、従来の1000倍の速度で有機分子を分離できる超高性能ろ過フィルターを開発することに成功した。

  • Fabrication of mesopore and macropore for porous polymer materials

    佐光 貞樹, クリスナン モハン ラジ, 藤井 義久, 一ノ瀬 泉

    第28回茨城地区「若手の会」交流会 

    Presentation date: 2013.10

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    本発表では、マクロ孔の造孔剤として無機粒子を添加した高分子/無機微粒子の混合溶液を使用し、高分子多孔体においてナノからマクロまでの幅広い階層的な細孔構造を制御する手法を報告する。

  • mesoporous polymer Nanofiber with mesoporous structure

    佐光 貞樹, クリスナン モハン ラジ, 一ノ瀬 泉

    第62回高分子討論会 

    Presentation date: 2013.09

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    高分子多孔体の細孔構造は、物質透過・吸着・分離特性といった高分子物性と密接に関係しており、その制御法は、高分子材料の性能向上を実現するために重要な役割を果たす。本研究では、マクロ孔やメソ孔といった幅広い階層的な細孔構造を精密に制御する手法を報告する。

  • Mechanical and Physical Properties of Ultrathin Naoporous Carbon Film

    藤井 義久, 佐光 貞樹, 一ノ瀬 泉

    第62回高分子討論会 

    Presentation date: 2013.09

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    種々の条件で作製したカーボン薄膜の物性評価を行った。作製条件によるカーボン薄膜の構造と物性の関係について紹介する。

  • Solid-liquid phase separation and vitrification of polymer solutions

    佐光 貞樹

    つくばソフトマター研究会2013 

    Presentation date: 2013.03

     View Summary

    我々は、溶媒分子の長距離の拡散を抑制する観点から、高分子溶液を急冷により凍結し、ガラス状態でのゆるやかな温度昇温により溶媒分子の冷結晶化を誘起させた。これにより、高分子の驚くほど緻密なミクロ相分離を実現し、低温下で溶媒を除去することで数10 nmの連続的な細孔を持つナノ多孔体を形成することに成功した。

  • Mesoporous Nanofiber Networks Created from Nano-crystallization of Polymer Solution

    SAMITSU, Sadaki

    Fourth International Symposium for Young Organic Chemists 

    Presentation date: 2013.03

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    Phase separation of polymer solutions has been used as a main route in industry to fabricate porous polymer materials (membranes and absorbents). Despite the long-term history (over 50 years), direct fabrication of mesopores without block-copolymer is still challenging. Here we propose a novel mechanism of phase separation in polymer solutions, which is related to crystallization of solvent molecules. Dispersed polymer chains significantly disturb the crystallization of the solvent molecules and therefore reduce the crystal size of the solvent molecules to be down to ten nanometers or so. Based on this concept, we have successfully fabricated mesoporous polymers consisting of three-dimensional network of ultrafine polymer nanofibers. We have also revealed physico-chemical properties of pol

  • ナノポーラスポリマーのTEMトモグラフィー観察

    長谷川 明, 小川展弘, 佐光 貞樹, 一ノ瀬 泉

    先端計測シンポジウム 

    Presentation date: 2013.02

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    ナノポーラス材料は、有害ガス分離・吸着などに利用できるので、盛んに研究されている。我々はネットワーク状ナノファイバー構造を有するナノポーラスポリマー材料を製作した1)。SEM観察、ガス吸着測定などにより、比表面積が大きいことがわかった。一方、内部空孔の連結状態の確認、空孔率の直接的な測定の評価はこの材料の応用の面において、重要である。本発表は透過電子顕微鏡トモグラフィー法を用いて、直接構造観察、空孔率、比表面積の定量解析を試みた。

  • Nanocrystallization in polymer solutions, fabrication of mesoporous materials and their functions

    佐光 貞樹

    2012 高分子・ハイブリッド材料研究センター 若手フォーラム 

    Presentation date: 2012.12

     View Summary

    我々は、溶媒分子の長距離の拡散を抑制する観点から、高分子溶液を急冷により凍結し、ガラス状態でのゆるやかな温度昇温により溶媒分子の冷結晶化を誘起させた。これにより、高分子の驚くほど緻密なミクロ相分離を実現し、低温下で溶媒を除去することで数10 nmの連続的な細孔を持つナノ多孔体を形成することに成功した。

  • Mesoporous materials fabricated by nano-crystallization of polymer solutions

    佐光 貞樹

    第27回茨城地区「若手の会」交流会 

    Presentation date: 2012.11

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    我々は、溶媒分子の長距離の拡散を抑制する観点から、高分子溶液を急冷により凍結し、ガラス状態でのゆるやかな温度昇温により溶媒分子の冷結晶化を誘起させた。これにより、高分子の驚くほど緻密なミクロ相分離を実現し、低温下で溶媒を除去することで数10 nmの連続的な細孔を持つナノ多孔体を形成することに成功した。

  • Quantitative analysis of porosity of nanoporous polymer with TEM tomography

    HASEGAWA, Akira, Nobuhiro Ogawa, SAMITSU, Sadaki, ICHINOSE, Izumi

    IUMRS-ICEM 2012 

    Presentation date: 2012.09

     View Summary

    We fabricated nanoporous polymers with an interconnected fiber network structure. The nanoporous polymers have very large ratio of surface to mass confirmed by SEM observation and gas absorption measurements. The present work aims to quantitatively evaluate the porosity of the materials by means of 3-dimensional transmission electron microscopy (TEM) in order to understand the superior performance of these materials. The pores of the nanoporous polymers were observed by TEM clearly. Slice images were obtained from the resulted tomogram. The ratios of pore to mass and surface to mass were analyzed quantitatively from the slice images. The details of the analysis and the results will be discussed.

  • Mesoporous nanofiber networks fabricated by nanocrystallized phase separation of polymer solution

    佐光 貞樹, クリスナン モハン ラジ, 一ノ瀬 泉

    第61回高分子討論会 

    Presentation date: 2012.09

     View Summary

    我々の最近の研究から、高分子鎖の存在により溶媒分子の結晶化挙動がナノレベルまで空間的に微細化されることが明らかになりつつある。このような溶媒分子のナノ結晶化現象は、高分子のナノ相分離構造を生み出す駆動力としても有効に機能し、高分子材料の産業応用上も非常に重要である。Here we present a new mechanism of phase separation in polymer solution, which allows us to fabricate nanoscale network of polymer nanofibers. A polymer network significantly disturbs crystallization of solvent molecules and therefore reduces the crystal size of solvent molecules to be down to ten nanometers. The mechanism will be important in polymer industry as well as polymer science because it has a potential for large-scale fabrication of separation membrane with nanopores.

  • Observation of nano-porous polymer with TEM tomography

    長谷川 明, 小川 展弘, 佐光 貞樹, 一ノ瀬 泉

    日本顕微鏡学会第68回学術講演会 

    Presentation date: 2012.05

     View Summary

    ネットワーク状ナノファイバー構造を有するナノポーラスポリマー材料を製作した。SEM観察、ガス吸着測定などにより、比表面積が大きいことがわかった。一方、内部空孔の連結状態の確認、空孔率の直接的な測定の評価はこの材料の応用の面において、重要である。本発表は透過電子顕微鏡トモグラフィー法を用いて、直接構造観察、空孔率、比表面積の定量解析を試みた。材料片は樹脂に包埋し、クライオウルトラミクロトームにより厚さ約300 nmの切片を作製した。切片はオスミウム蒸気で染色後、JEM-2100Fで観察した。電子線トモグラフィーは傾斜ステップ1°或いは2°で実施し、傾斜角度範囲を最大−70°~+70°に設定した。TEM画像では、試料ブロック内の空孔が鮮明に観察された。再構成した断層像により、ブロック内の空孔率及び比表面積を定量解析に試みた。発表では、解析方法及び結果を詳細に報告する。

  • Polymer Nanofiber Networks as nanoporous and high-surface-area material

    佐光 貞樹, 一ノ瀬 泉

    第26回茨城地区「「若手の会」交流会 

    Presentation date: 2011.11

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    ポリスチレン(PS)やポリスルホン(PSF)を含む様々な非晶性汎用高分子に対して、直径が約10 nm程度の極細のファイバーからなる「ネットワーク状のナノ相分離構造」をグラムスケールで形成することに成功した。このネットワーク状高分子ナノファイバーは、200 m2/gを越える比表面積を有しており、また、緻密なナノファイバー構造により、5&#8212;20nm程度のナノ細孔を持ち、メソ細孔材料として、分離機能をもつ吸着材、医療用途で用いられる徐放剤などの応用が期待できる。今回、非晶性のナノファイバーネットワークが示す特異なガス吸収特性の検討を行なった。表面近傍での吸収過程を利用しているため、CO2の飽和吸着量の90%までが1分以内で吸着し、減圧することで素早く脱着する。即ち、高速かつ可逆的な吸脱着が可能になった。

  • Nanoscale phase separation of polymer solution driven by crystallization of solvent molecules

    佐光 貞樹, 一ノ瀬 泉

    第60回高分子討論会 

    Presentation date: 2011.09

     View Summary

    高分子濃厚溶液について、ソフトマター物理学の立場から再考してみたい。従来の高分子理論では、高分子の運動性は数多く議論されてきたが、溶媒分子は高分子を分散させる平均場として扱われてきたため、溶媒分子の特性を直接的に扱った検討例は少ない。一方で、複数成分の混合系であることに着目すると、溶媒分子は高分子鎖の運動と強く結合しているため、高分子鎖の遅い運動性は溶媒分子の運動性にも強く影響し、溶媒分子の結晶化や溶液のガラス化挙動が変化することは容易に想像できる。実際、我々の最近の実験から、高分子鎖の存在により溶媒分子の結晶化挙動がナノレベルまで空間的に微細化されることが明らかになりつつある。このような溶媒分子のナノ結晶化現象は、高分子のナノ相分離構造を生み出す駆動力としても有効に機能し、ナノ細孔を持つ分離膜の工業的製法として高分子材料の産業応用上も非常に重要である。

  • Micro-Phase Separation of Polymers by Nano-Clustered Solvents

    佐光 貞樹, 一ノ瀬 泉

    第63回コロイドおよび界面化学討論会 

    Presentation date: 2011.09

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    我々は、ポリスチレンやポリスルホン(PSF)を含む様々な汎用高分子に対して、その濃厚溶液を急冷して得たガラス状態から溶媒置換により良溶媒を除去することで、直径10 nm程度のファイバーが得られることを見出した。本発表では、ポリマーの濃厚溶液中で形成される高分子鎖の3次元ネットワークを、溶媒分子を閉じ込めるソフトなナノ空間として考えてみたい。

  • Gas separation application of polymer nanofiber network

    佐光 貞樹, 一ノ瀬 泉

    第72回応用物理学会学術講演会 

    Presentation date: 2011.09

     View Summary

    ガスの分離・貯蔵技術は次世代社会のインフラを支える基盤技術になる。物理・化学吸収法に代わるコンパクトで省エネルギーなガス分離手法として、有望な圧力スウィング法に着目する。圧力で駆動されるナノ細孔へのガス分子の吸脱着を利用するガス分離技術で、ゼオライトや活性炭などサブナノメートルサイズの細孔を多数持つ無機多孔質材料が吸着剤として用いられてきた。一方、本発表では、圧力変化によりガス分子がやわらかい高分子材料の内部まで浸透する現象を利用した新しいガス分離のコンセプトを提案する。ネットワーク状高分子ナノファイバーは、高分子表面近傍での吸収挙動を利用してガスを分離するため、ガスの選択性と吸収容量が高分子への溶解度(親和性)で決定されるという点で、従来の多孔質物質の細孔への吸着法とは原理的に異なる。水分子など細孔に凝縮しやすいガス成分が共存する場合のガス分離材料として将来性が期待される。

  • Characterization on surface properties of polymer nanofiber network

    佐光 貞樹, クリスナン モハン ラジ, 一ノ瀬 泉

    第60回高分子学会年次大会 

    Presentation date: 2011.05

     View Summary

    我々は、直径が15 nm程度まで微細化された高分子ナノファイバーの3次元ネットワーク構造からなるバルク高分子多孔体の創製に成功した。この本発表では、示差走査熱量計、固体NMR、ガス吸着測定などの評価手法を適用することにより、高分子ナノファイバーの表面物性を明らかにした。

  • Fabrication of Polymer Nanofiber Networks and their Surface Function

    佐光 貞樹, 張 鋭, 彭 新生, 一ノ瀬 泉

    第60回高分子学会年次大会 

    Presentation date: 2011.05

     View Summary

    高分子濃厚溶液を急冷して得たガラス状態から、溶媒分子の冷結晶化を利用することで、溶媒凍結状態で相分離を誘起した。凍結状態を維持できる低温で、液体状態の貧溶媒を大量に導入して溶媒交換を実施し、良溶媒を除去することで、高分子ナノ相分離構造を固定化し、直径が10 nm程度の極細のファイバーからなるネットワーク状構造体を得ることに成功した。本研究では、溶媒分子の運動性を凍結したガラス状態から相分離させるため、緻密なナノ構造を得られることが新しい着目点である。得られた極細ネットワーク状高分子ナノファイバー材料は、200 m2/gを越える比表面積を示しており、高分子の表面領域に限定されていた特異な物性をバルクの材料物性として発現できる可能性がある。当日の発表では、高分子表面のガスや蒸気の吸収特性に着目して報告する予定である。

  • Separation Performance of Polystyrene Nanofiber Network in Aqueous Solution System

    クリスナン モハン ラジ, 佐光 貞樹, 一ノ瀬 泉

    第60回高分子学会年次大会 

    Presentation date: 2011.05

     View Summary

    Polymer nanofiber network with a large specific surface area is useful for the purification of contaminated water. Here we report surface modification of polymer nanofibers and their separation performance of hazardous organic compounds dissolved in water.

  • Fabrication of polymer nanofiber networks and their surface functionality

    佐光 貞樹

    つくばソフトマター研究会2011 

    Presentation date: 2011.03

     View Summary

    高分子濃厚溶液を急冷して得たガラス状態から、溶媒分子の冷結晶化を利用することで、溶媒凍結状態で相分離を誘起した。凍結状態を維持できる低温で、液体状態の貧溶媒を大量に導入して溶媒交換を実施し、良溶媒を除去することで、高分子ナノ相分離構造を固定化し、直径が10 nm程度の極細のファイバーからなるネットワーク状構造体を得ることに成功した。従来の研究では、溶媒分子が運動性を保持した状態で相分離が進行するため、最終的な相分離構造はマイクロメートルスケール以上まで粗大化してしまうが、本研究では、溶媒分子の運動性を凍結したガラス状態から相分離させるため、緻密なナノ構造を得られることが新しい着目点である。得られた極細ネットワーク状高分子ナノファイバー材料は、200 m2/gを越える比表面積を示しており、高分子の表面領域に限定されていた特異な物性をバルクの材料物性として発現できる可能性がある。

  • Fabrication of conductive polymer nanofibers and their carrirer transprot properties

    佐光 貞樹

    10-2高分子基礎物性研究会 

    Presentation date: 2011.03

     View Summary

    高分子系有機材料を半導体層として用いた電界効果トランジスタは軽量で柔軟な大面積デバイスを低価格で作製できるという利点が挙げられており注目を集めている。塗布法を使用することで素子作製プロセスが簡便に行えるという特徴を生かすことができる反面、ペンタセンなどの低分子系に比べて移動度が一桁程度低い値に留まっているのが現状である。最近の研究から塗布した高分子の表面形態がデバイス特性に大きな影響を与えているという報告が相次ぎ、高移動度を実現するために有機材料の探索やデバイス作製条件の最適化で精力的な研究が行われている。本研究では代表的な有機高分子系材料として使用されているポリ(3-アルキルチオフェン)を用いてナノファイバーを作製し、ナノファイバー薄膜のトランジスタ特性を測定することで高分子の形態との関係を明らかにし、ナノファイバーを用いた高分子系有機トランジスタの新しいデバイス構造を提案した。

  • Fabrication of Ultrafine Polymer Nanofiber Networks and their Application to Gas Separation

    SAMITSU, Sadaki, ICHINOSE, Izumi

    9th Japan-France Workshop on Nanomaterials 

    Presentation date: 2010.11

     View Summary

    Rapid freezing of a polymer solution gave a glassy state of the solution. Solvent molecules frozen at the glassy solution were sufficiently exchanged with a poor solvent under a low temperature that held the solution to be frozen state. This process successfully results in formation of network structure of polymer nanofibers. The average diameter of the nanofibers is as thin as ca. 15 nm. We further investigated the potential of the nanofiber network in gas separation applications and found that the nanofiber network gave rubber-like gas absorption in spite of glassy nature of the initial polymer. These unique properties of the nanofiber network probably result from its small diameter and high surface area.

  • Gas separation applications of polymer nanfiber networks

    佐光 貞樹, 一ノ瀬 泉

    第24回日本吸着学会研究発表会 

    Presentation date: 2010.11

     View Summary

    ガスの分離・貯蔵技術は次世代社会のインフラを支える基盤技術になる可能性がある。物理・化学吸収法に代わるコンパクトで省エネルギーなガス分離手法として、有望な圧力スウィング法に着目する。圧力で駆動されるナノ細孔へのガス分子の吸脱着を利用するガス分離技術で、ゼオライトや活性炭などサブナノメートルサイズの細孔を多数持つ無機多孔質材料が吸着剤として用いられてきた。一方、本発表では、圧力変化によりガス分子がやわらかい高分子材料の内部まで浸透する現象を利用した新しいガス分離のコンセプトを提案する。ネットワーク状高分子ナノファイバーは、高分子表面近傍での吸収挙動を利用してガスを分離するため、ガスの選択性と吸収容量が高分子への溶解度(親和性)で決定されるという点で、従来の多孔質物質の細孔への吸着法とは原理的に異なる。水分子など細孔に凝縮しやすいガス成分が共存する場合のガス分離材料として将来性が期待される。

  • Fabrication of conducting polymer nanofibers and their field-effect transistor characteristics

    佐光 貞樹

    第25回茨城地区「若手の会」交流会 

    Presentation date: 2010.10

     View Summary

    高分子系有機材料を半導体層として用いた電界効果トランジスタは軽量で柔軟な大面積デバイスを低価格で作製できるという利点が挙げられており注目を集めている。塗布法を使用することで素子作製プロセスが簡便に行えるという特徴を生かすことができる反面、ペンタセンなどの低分子系に比べて移動度が一桁程度低い値に留まっているのが現状である。最近の研究から塗布した高分子の表面形態がデバイス特性に大きな影響を与えているという報告が相次ぎ、高移動度を実現するために有機材料の探索やデバイス作製条件の最適化で精力的な研究が行われている。本研究では代表的な有機高分子系材料として使用されているポリ(3-アルキルチオフェン)を用いてナノファイバーを作製し、ナノファイバー薄膜のトランジスタ特性を測定することで高分子の形態との関係を明らかにし、ナノファイバーを用いた高分子系有機トランジスタの新しいデバイス構造を提案する。

  • Polymer nanostructure fabricated by phase separation through glassy state of a polymer solution

    佐光 貞樹, 一ノ瀬 泉

    日本物理学会 2010年秋季大会 

    Presentation date: 2010.09

     View Summary

    高分子濃厚溶液を液体窒素中で急冷し、溶液全体が凍結したガラス状態を得た。低温で凍結状態を維持したまま、液体状態の貧溶媒を導入して溶媒交換により良溶媒を除去することで、高分子のナノ相分離構造を形成することに成功した。従来の高分子溶液の相分離現象では、溶媒分子が運動性を維持した液体状態で相分離が進行するが、本研究では、溶媒分子の運動性を凍結した状態で相分離が発現する点が全く異なる。

  • Fabrication of Polymer Nanofiber Networks and the Gas Separation

    佐光 貞樹, 張 鋭, 彭 新生, 一ノ瀬 泉

    第59回高分子討論会 

    Presentation date: 2010.09

     View Summary

    高分子濃厚溶液を液体窒素中で急冷し、溶液全体が凍結したガラス状態を得た。低温で凍結状態を維持したまま、液体状態の貧溶媒を大量に導入して溶媒交換を実施し、良溶媒を除去することで、直径が10nm程度の極細のファイバーからなる高分子ナノ相分離構造を形成することに成功した。従来の研究では、溶媒分子が運動性を保持した状態で相分離が進行するため、最終的な相分離構造はマイクロメートルスケール以上まで粗大化してしまうが、本研究では、溶媒分子の運動性を凍結した状態で相分離させるため、緻密なナノ構造を得られることが新しい点である。得られたネットワーク状高分子ナノファイバーは、200m2/gを越える比表面積を示しており、高分子の表面領域に限定されていた特異な物性をバルクの材料物性として発現できる可能性がある。当日の発表では、高分子表面のガス吸収特性に着目して報告する予定である。

  • Molecular Manipulator Driven by Spatial Variation of Liquid Crystalline Order

    佐光 貞樹, 高西 陽一, 山本 潤

    第59回高分子討論会 

    Presentation date: 2010.09

     View Summary

    液晶・ソフトマター混合系において、液晶相の配向方向との結合に着目した研究が数多くある一方、液晶相の秩序度との結合に着目した研究はほとんどなかった。九大の菊池らによって見いだされた高分子安定化ブルー相[1]にヒントを得て、我々は液晶秩序の空間勾配に着目し、人為的に生成した液晶秩序度により混合物の濃度を自在に制御する、新しい分子マニュピレータの原理の提案と実証の研究を行なった。液晶秩序は不純物分子をできるだけ秩序度の低い領域に局在させようとする力の“場”を生み出すはずである。液晶秩序度の空間勾配を人為的に作り出すことで、不純物分子の輸送を制御する分子マニュピレーションの新しい原理を発案し、モデル実験を行ってこの相互作用の存在を実証した。この分子マニピュレーターは液晶秩序度の空間勾配という”場”を制御することにより、分子の輸送を制御する点において、レーザーピンセットなどの従来法とは異なる原理に基づ

  • Molecular manipulator driven by spatial variation of scalar order parameter

    佐光 貞樹

    つくばソフトマター研究会 2010 

    Presentation date: 2010.02

     View Summary

    我々は、液晶秩序の空間勾配に着目し、人為的に生成した液晶秩序度により混合物の濃度を自在に制御する、新しい分子マニュピレータの原理の提案と実証の研究を行った。混合された分子は液晶秩序に対して不純物として作用するため、その近傍の液晶秩序を著しく乱す。このため液晶秩序は、不純物分子をできるだけ秩序度の低い領域に局在させようとする力の“場”を生み出すはずである。そこで我々は、液晶秩序度の空間勾配を人為的に作り出すことで、不純物分子の輸送を制御する分子マニュピレーションの新しい原理を発案し、モデル実験を行ってこの相互作用の存在を実証する。

  • Molecular manipulator driven by spatial variation using azobenzene

    佐光 貞樹

    液晶学会合同フォーラム講演会 

    Presentation date: 2009.11

     View Summary

    我々は、液晶秩序の空間勾配に着目し、人為的に生成した液晶秩序度により混合物の濃度を自在に制御する、新しい分子マニュピレータの原理の提案と実証の研究を行った。混合された分子は液晶秩序に対して不純物として作用するため、その近傍の液晶秩序を著しく乱す。このため液晶秩序は、不純物分子をできるだけ秩序度の低い領域に局在させようとする力の“場”を生み出すはずである。そこで我々は、液晶秩序度の空間勾配を人為的に作り出すことで、不純物分子の輸送を制御する分子マニュピレーションの新しい原理を発案し、モデル実験を行ってこの相互作用の存在を実証する。この分子マニピュレーションは液晶秩序度の空間勾配という”場”を制御することにより、分子の輸送を制御する点において、レーザーピンセットなどのように、プローブと対象の直接的な相互作用に基づく従来法とは異なる原理に基づくマニピュレーション法である。

  • Molecular manipulator driven by spatial variation of order paramter

    佐光 貞樹

    第24回茨城地区「若手の会」交流会 

    Presentation date: 2009.10

     View Summary

    我々は、液晶秩序の空間勾配に着目し、人為的に生成した液晶秩序度により混合物の濃度を自在に制御する、新しい分子マニュピレータの原理の提案と実証の研究を行った。混合された分子は液晶秩序に対して不純物として作用するため、その近傍の液晶秩序を著しく乱す。このため液晶秩序は、不純物分子をできるだけ秩序度の低い領域に局在させようとする力の“場”を生み出すはずである。そこで我々は、液晶秩序度の空間勾配を人為的に作り出すことで、不純物分子の輸送を制御する分子マニュピレーションの新しい原理を発案し、モデル実験を行ってこの相互作用の存在を実証する。この分子マニピュレーションは液晶秩序度の空間勾配という”場”を制御することにより、分子の輸送を制御する点において、レーザーピンセットなどのように、プローブと対象の直接的な相互作用に基づく従来法とは異なる原理に基づくマニピュレーション法である。

  • Molecular manipulator driven by spatial variation of order paramter

    佐光 貞樹

    伊藤耕三研究室セミナー 

    Presentation date: 2009.10

     View Summary

    液晶・ソフトマター混合系では、これまで液晶相の配向方向と混合物の自由度との結合に着目した研究は数多くありますが、液晶相の秩序度との結合に着目した研究はほとんどありませんでした。ここでは、液晶秩序の空間勾配に着目し、人為的に生成した液晶秩序度により混合物の濃度を自在に制御する、新しい分子マニュピレータの原理の提案と実証の研究を行なった結果を報告します。NIMSをとりまく現状についても紹介する予定です。

▼display all

Research Projects

  • 新規その場光ナノ計測法による高分子の核生成過程の解明とナノ多孔化技術への応用

    日本学術振興会  科学研究費助成事業

    Project Year :

    2021.04
    -
    2024.03
     

    佐光 貞樹, 廣井 卓思

     View Summary

    本年度はポリエーテルスルホン(PES)をモデル高分子として、ニトロベンゼン溶液で起きる溶媒誘起結晶化挙動を詳細に検討した。高分子濃度と結晶化温度を変えたときの結晶化過程を透過率測定で追跡した。結晶化温度が低く、高分子濃度が高いほど透過率の減少速度が速く、結晶化が速く進行することを確認した。得られた微粒子の大きさと形状はSEMとレーザー回折粒度分布計で評価した。濃度20 wt%の溶液からは平均粒径が5μmの球状微粒子が得られ、粒子表面には多数の微細孔が確認できた。微粒子の微多孔質構造はガス吸着測定で定量的に評価した。平均細孔径は7 nmで空隙率44%の多孔構造が確認できた。PESの結晶構造はX線回折で評価し、融点をDSCで決定した。PESとニトロベンゼンが共結晶を形成していることを、FT-IR・ラマンスペクトル・TGAで確認した。PES濃度を変えたときの粒径・結晶性・微多孔質構造の変化と結晶化過程での溶液撹拌の有無による結晶化挙動の違いから、溶液撹拌によってできた結晶断片が種結晶(シード)として働き、微粒子の生成を促進している結晶化機構を提案した。結晶化で得られた多孔質PES微粒子の評価と並行して、結晶化過程を追跡するための動的光散乱装置の立ち上げを進めた。レーザーを使った動的光散乱(DLS)測定の光学系を構築して、ポリスチレン標準微粒子(粒径100 nm)でDLS測定ができることを実証した。光散乱強度は粒径の増加によってべき乗で増大するため、DLS測定では一般に粗大粒子や溶液中のゴミの影響を受けやすく、サイズの異なる粒子が混在すると測定が難しい場合がある。この課題を回避するため、ノイズを回避できるデータ解析システムを考案した。

  • イオン液体を用いたダイラタンシー現象の衝撃緩和機構解明

    Acquisition, Technology & Logistics Agency  安全保障技術研究推進制度 タイプ(C)

    Project Year :

    2019
    -
    2021
     

    Sadaki Samitsu

  • ランダムな内部構造を持つ多孔質高分子粉体による構造色の研究

    Japan Society for the Promotion of Science  Grant-in-Aid for Scientific Research ?

    Project Year :

    2017
    -
    2019
     

    Sadaki Samitsu

  • Fabrication of multicomponent nanoporous polymers involving polymer interfaces and their separation functions

    Japan Society for the Promotion of Science  Grant-in-Aid for Scientific Research ?

    Project Year :

    2014
    -
    2016
     

    Sadaki Samitsu

  • Preparation of Polymer Nanofiber Networks through Newly Developed Nanoscale Phase Separation Mechanism

    Japan Society for the Promotion of Science  Grant-in-Aid for Young Scientists (A)

    Project Year :

    2011
    -
    2013
     

    Sadaki Samitsu

  • Molecular manipulator driven by spatial variation of molecular order

    Japan Society for the Promotion of Science  Grant-in-Aid for Young Scientists (B)

    Project Year :

    2009
    -
    2010
     

    Sadaki Samitsu

     View Summary

    Previous studies on liquid crystal systems containing impurities such as colloidal particles have focused on the collective long-range interactions among micron-scale impurities, resulting from elastic distortion of the liquid crystalline order. Here, we propose a novel mechanism in which the spatial variation of S generates a 'force' that transports nano-scale solutes mediated by the coupling between S and solute concentration. We have successfully designed a prototype of a molecular manipulator that transports a molecular solute along spatial variations of the scalar order parameter, modulated in a controlled manner by spot illumination of an azobenzene-doped nematic phase by UV light. The manipulator can control the spatial variation of the polymer concentration; therefore it shows promise for use in the design of novel hybrid soft materials.

  • 液晶配向場を用いた導電性高分子の配向制御

    Japan Society for the Promotion of Science  Grant-in-Aid for Young Scientists (Start-up)

    Project Year :

    2006
    -
    2007
     

    Sadaki Samitsu

▼display all

Misc

  • Synthesis of Luminescent Hydroxyapatite Nanoparticles Coordinated with Citric Acid for Their Bifunctional Cell-Labeling and Cytostatic Suppression Properties

    片岡卓也, 片岡卓也, 佐光貞樹, 多賀谷基博

    日本セラミックス協会年会講演予稿集(Web)   2021  2021

    J-GLOBAL

  • 急速凍結過程を用いた高分子メソ多孔化法

    佐光貞樹, 藤井義久, 一ノ瀬泉

    ポリマー材料フォーラム講演予稿集   24th   184  2015.11

    J-GLOBAL

  • ナノ結晶化相分離法による高分子の多孔化技術

    佐光貞樹, 藤井義久, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   64 ( 2 ) ROMBUNNO.2H17  2015.08

    J-GLOBAL

  • プラズマ励起CVD法による逆浸透膜の開発

    佐光貞樹, 佐光貞樹, 藤井義久, 藤井義久, 一ノ瀬泉, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   64 ( 2 ) ROMBUNNO.3PB098  2015.08

    J-GLOBAL

  • 多孔性カーボン膜の分離特性

    藤井義久, 佐光貞樹, 一ノ瀬泉

    繊維学会予稿集   70 ( 1 (CD-ROM) ) ROMBUNNO.1P143  2015.06

    J-GLOBAL

  • ナノカーボン膜の力学特性

    藤井義久, 佐光貞樹, 一ノ瀬泉

    レオロジー討論会講演要旨集   62nd   268 - 269  2014.10

    J-GLOBAL

  • ナノ粒子を含む高分子メソ多孔体の作製

    佐光貞樹, KRISHNAN Mohan Raj, 藤井義久, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   63 ( 2 ) ROMBUNNO.2PF034  2014.09

    J-GLOBAL

  • ナノ細孔を有するカーボン超薄膜の分離特性

    藤井義久, 佐光貞樹, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   63 ( 2 ) ROMBUNNO.1PC037  2014.09

    J-GLOBAL

  • ナノ細孔を有するカーボン超薄膜の熱物性

    藤井義久, 佐光貞樹, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   63 ( 1 ) ROMBUNNO.1PE051  2014.05

    J-GLOBAL

  • 高分子メソ多孔体の細孔制御における溶媒の効果

    佐光貞樹, KRISHNAN Mohan Raj, 藤井義久, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   63 ( 1 ) ROMBUNNO.1PG023  2014.05

    J-GLOBAL

  • ナノ細孔を有するカーボン超薄膜の力学特性

    藤井義久, 佐光貞樹, 一ノ瀬泉

    繊維学会予稿集   69 ( 1 (CD-ROM) ) ROMBUNNO.2P124  2014

    J-GLOBAL

  • ナノ結晶化相分離法を用いた高分子メソ多孔体の創製とその応用

    佐光貞樹, 藤井義久, 一ノ瀬泉

    繊維学会予稿集   69 ( 1 (CD-ROM) ) ROMBUNNO.1D04  2014

    J-GLOBAL

  • マクロ細孔を導入した高分子メソ多孔体の作製

    佐光貞樹, KRISHNAN Mohan Raj, 藤井義久, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   62 ( 2 ) ROMBUNNO.3PC033  2013.08

    J-GLOBAL

  • ナノ細孔を有するカーボン超薄膜の力学物性

    藤井義久, 佐光貞樹, 一ノ瀬泉

    高分子学会予稿集(CD-ROM)   62 ( 2 ) ROMBUNNO.2PC053  2013.08

    J-GLOBAL

  • 地球規模の問題を解決するための分離機能材料

    一ノ瀬泉, 佐光貞樹, 藤井義久

    NIMS NOW   12 ( 7 ) 06  2012.09

    J-GLOBAL

  • Preparation and characterization of self-assembled conducting polymer nanofibers(Poster session 2, New Frontiers in Colloidal Physics : A Bridge between Micro- and Macroscopic Concepts in Soft Matter) :

    Samitsu Sadaki, Shimomura Takeshi, Ito Kohzo

      89 ( 1 ) 159 - 160  2007

     View Summary

    We prepared one-dimensional nanofibrillar structure of poly(3-alkylthiophenes) (P3ATs) via whisker precipitation in anisole. P3ATs self-assembled into nanofibers whose height and aspect ratio was 5nm and on the order of 10^3, respectively. UV-Vis absorption spectra showed the relationship between the change of absorption spectra and nanofiber formation in P3ATs solutions. X-ray diffraction measurements showed P3AT nanofibers involve microcrystalline structures. The results indicate that crystallization of P3ATs in a solution, which was driven by strong π-π interaction between polymer backbones, plays a crucial role in nanofiber formation.

    CiNii

  • 高分子1本の導電性を測る

    下村武史, 佐光貞樹, 伊藤耕三

    現代化学   ( 441 ) 17 - 23  2007

    CiNii

  • Conductivity measurements of PEDOT nanowires on nanoelectrodes

    Sadaki Samitsu, T Iida, M Fujimori, S Heike, T Hashizume, T Shimomura, K Ito

    SYNTHETIC METALS   152 ( 1-3 ) 497 - 500  2005.09

     View Summary

    We have prepared very thin, conducting polymer nanowires of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) with diameters under 5nm on a thermally grown SiO2/Si substrate by a molecular combing method. We have measured the conductivity of the nanowires using nanoelectrodes. Ohmic behavior of the PEDOT nanowires was obtained when applied voltages were smaller than 100 mV. The conductance of the nanowires decreased with decreasing temperature and the temperature dependence of the conductance was explained by the quasi one-dimensional variable range hopping (VRH) model. After all the nanowires placed on the gap of the nanoelectrodes were cut, the current was drastically decreased, down to the background level. We have thus provided direct evidence that the PEDOT nanowires were responsible for conduction between the nanoelectrodes.

    DOI

  • Conductivity measurements of individual poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) nanowires on nanoelectrodes using manipulation with an atomic force microscope

    Sadaki Samitsu, T Shimomura, K Ito, M Fujimori, S Heike, T Hashizume

    APPLIED PHYSICS LETTERS   86 ( 23 ) 233103-1-233103-3  2005.06

     View Summary

    We have prepared conducting polymer nanowires of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) with diameters under 10 nm by a molecular combing method, and have measured the conductivity of the individual PEDOT nanowires on platinum nanoelectrodes using manipulation with an atomic force microscope (AFM). The temperature dependence of the conductance was explained well by a quasi-one-dimensional variable range hopping model. The conductivity of two single nanowires was determined to be 0.6 and 0.09 S/cm, which is of the same order as that of PEDOT/PSS films. After all the nanowires crossed over the nanoelectrodes were cut off with AFM manipulation, the current was drastically decreased down to the background level. These results directly indicate that the conductivity was derived from the PEDOT nanowires on the nanoelectrodes. (c) 2005 American Institute of Physics.

    DOI

  • Immobilization of molecular tubes on self-assembled monolayers of beta-cyclodextrin and dodecanethiol inclusion complexes

    Sadaki Samitsu, T Shimomura, K Ito, M Hara

    APPLIED PHYSICS LETTERS   85 ( 17 ) 3875 - 3877  2004.10

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    A molecular tube (MT) is a tubular macromolecule formed by the one-dimensional linkage of alpha-cyclodextrins and exhibits molecular recognition for selecting the diameter of a polymer chain. In this letter, we immobilized MTs on a self-assembled monolayers (SAM) of inclusion complexes (DDT-CD) between dodecanethiol (DDT) and beta-cyclodextrin (beta-CD). The DDT-CD inclusion complexes formed uniform self-assembled monolayers on gold. We confirmed that the MTs were immobilized on the DDT-CD SAM using dynamic contact angle measurements, surface-plasmon resonance (SPR), and scanning probe microscopy (SPM). (C) 2004 American Institute of Physics.

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    Waseda Research Institute for Science and Engineering   Concurrent Researcher