Hitoshi Ogihara

Tokyo Institute of Technology, Edo, Tōkyō, Japan

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Publications (42)82.89 Total impact

  • Hitoshi Ogihara, Jing Xie, Tetsuo Saji
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    ABSTRACT: Carbon nanotubes (CNTs) are a promising material for superhydrophobic coating. In the present study, we prepared superhydrophobic CNT films by spraying CNT dispersions, and discussed the factors that control superhydrophobicity of the CNT films. Three types of dispersions (i.e., CNTs/ethanol, CNTs functionalized with dodecyl groups/ethanol, and CNTs and trimethylsiloxysilicate (TMSS)/ethanol) were prepared as spraying solutions. As increasing the amount of spray-coated CNTs, hydrophobicity of the resulting films became higher, and eventually superhydrophobicity was observed. The spray-coated CNT films had hierarchical roughness, which is preferable morphology to show superhydrophobicity. The coexistence of TMSS in the film lowered the amount of CNTs required to show superhydrophobicity because TMSS acted like glue that prevented CNTs from aggregating on substrates. Interaction force of CNTs also affected the wettability of the CNT films. The π–π interaction of CNTs resulted in the aggregation of them on substrates, which lowered the wettability of the films. From this viewpoint, functionalization of CNTs with dodecyl groups was effective to form superhydrophobic films because the dodecyl groups on CNTs screened the π–π interaction of CNTs.
    Journal of Materials Science 04/2014; 49(8). · 2.16 Impact Factor
  • Hitoshi Ogihara, Hui Wang, Tetsuo Saji
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    ABSTRACT: Ni─B/SiC composite films were electrodeposited using conventional Ni electrodeposition baths containing trimethylamine borane and SiC particles. In the present study, we examined the effect of SiC particle size, concentration of SiC particles in electrodeposition baths, thermal treatment, and current density on the properties (i.e., film hardness, SiC content, crystallite structure, and wear resistance) of the electrodeposited Ni─B/SiC composite films. The hardness of the composite films depended on the concentration of SiC particles in the baths; baths containing 1 and 8 g/L of SiC particles provided Ni─B/SiC films with a film hardness of 760 and 858 HV, respectively, which is because the SiC content in the composite films increased with increasing SiC particle concentration in the baths. Current density also affected the hardness of the composite films because both the SiC content and hardness of the Ni─B matrix changed with current density. Thermal treatment at 573 K in air had a significant influence on film hardness; for example, the hardness of Ni─B/SiC composite films was changed from 845 HV to 1499 HV after the thermal treatment. XRD patterns of the composite films revealed that thermal treatment results in a structural change of the Ni─B matrix from an X-ray amorphous structure to a crystalline Ni metal and Ni3B alloy, which leads to hardening of the composite films. Moreover, the Ni─B/SiC composite film showed higher anti-wear performance than Ni/SiC and Ni─P/SiC.
    Applied Surface Science 01/2014; 296:108–113. · 2.54 Impact Factor
  • Hitoshi Ogihara, Hiro Kibayashi, Tetsuo Saji
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    ABSTRACT: Patterned carbon nanotube (CNT)/acrylic resin composite films were prepared using microcontact printing (μCP). To prepare ink for μCP, CNTs were dispersed into propylene glycol monomethyl ether acetate (PGMEA) solution in which acrylic resin and a commercially available dispersant (Disperbyk-2001) dissolved. The resulting ink were spin-coated onto poly(dimethylsiloxane) (PDMS) stamps. By drying solvent components from the ink, CNT/polymer composite films were prepared over PDMS stamps. Contact between the stamps and glass substrates provided CNT/polymer composite patternings on the substrates. The transfer behavior of the CNT/polymer composite films depended on the thermal-treatment temperature during μCP; thermal treatment at temperatures near the glass-transition temperature (T(g)) of the acrylic resin was effective to form uniform patternings on substrates. Moreover, contact area between polymer and substrates also affect the transfer behavior. The CNT/polymer composite films showed high electrical conductivity, despite the nonconductivity of polymer components, because CNTs in the films were interconnected. The electrical conductivity of the composite films increased as CNT content in the film became higher; as a result, the composite patternings showed almost as high electrical conductivity as previously reported CNT/polymer bulk composites.
    ACS Applied Materials & Interfaces 08/2012; 4(9):4891-7. · 5.01 Impact Factor
  • Hitoshi Ogihara, Jing Xie, Jun Okagaki, Tetsuo Saji
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    ABSTRACT: Superhydrophobic and transparent coatings are deposited onto paper by spraying alcohol suspensions of SiO(2) nanoparticles. Superhydrophobicity depends on the aggregation states of nanoparticles, which are determined by the type of alcohol used in the suspensions. The superhydrophobicity of the paper is maintained after touching the paper with a bare finger.
    Langmuir 02/2012; 28(10):4605-8. · 4.38 Impact Factor
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    ABSTRACT: This paper proposes a novel approach for the preparation of colored films with a metallic luster and high hardness. The colored organic films were patterned as microdots by photolithography, and then honeycomb-shaped Ni walls were electrodeposited between the micropatterning. The organic/inorganic composite films showed the hardest grade in a pencil hardness test and high durability in wear resistance tests because the honeycomb-shaped Ni walls protected the colored organic dots.
    ACS Applied Materials & Interfaces 02/2012; 4(2):590-2. · 5.01 Impact Factor
  • Hitoshi Ogihara, Kaori Udagawa, Tetsuo Saji
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    ABSTRACT: Ni–B alloy films were electrodeposited using a conventional Ni plating bath containing dimethylamine borane (DMAB) or trimethylamine borane (TMAB) as boron sources. Properties (hardness, boron content, and crystalline structure) of the electrodeposited Ni–B alloy films were significantly affected by electrodeposition conditions (current density, pH, and the amount of boron sources in plating bath). X-ray amorphous Ni–B alloy films showed high hardness, whereas hardness of Ni–B alloy films that consisted of large crystallites was low. In TMAB bath, the crystalline structure of Ni–B alloy films was controlled by the amount of co-deposited boron atoms; however in DMAB bath, clear relationship between film hardness and boron content was not confirmed. The crystalline structure of Ni–B films was drastically changed by heat-treatment and the effect of structural changes on hardness was discussed.
    Surface and Coatings Technology 02/2012; 206(s 11–12):2933–2940. · 1.94 Impact Factor
  • Hitoshi Ogihara, Takafumi Katayama, Tetsuo Saji
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    ABSTRACT: SiO(2) particle/silicone resin (trimethylsiloxysilicate (TMSS)) composite coatings were prepared by electrophoretic deposition (EPD), and their wettability was examined. SiO(2) coatings prepared by EPD baths without TMSS were hydrophilic, while superhydrophobicity was observed for SiO(2)/TMSS composite coatings. IR spectra and EDS analyses revealed that not only SiO(2) particles but also TMSS electrophoretically moved toward a cathode; as a result, hydrophilic SiO(2) particles turned into superhydrophobic composite coatings by one-step EPD. SEM and AFM images of the superhydrophobic SiO(2)/TMSS composite coatings showed the presence of both nanometer- and micrometer-sized roughness in their surfaces. Particle size of SiO(2) had a great influence on the wettability of the composite coatings. The superhydrophobic SiO(2)/TMSS composite coatings showed excellent water repellency; they repelled running water continuously. In addition, by controlling the amount of deposited SiO(2) particles and TMSS, transparent superhydrophobic SiO(2)/TMSS composite coatings were prepared.
    Journal of Colloid and Interface Science 10/2011; 362(2):560-6. · 3.17 Impact Factor
  • Hitoshi Ogihara, Takafumi Katayama, Tetsuo Saji
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    ABSTRACT: We prepared electroless deposited Ni–B alloy films treated with trimethylsiloxysilicate (TMSS) that showed superhydrophobicity. Hydrophilic electroless deposited Ni–B films were made to be superhydrophobic by immersing them into an ethanolic solution of TMSS and water. This treatment lowered the surface energy of the electroless deposited Ni–B alloy films because hydrophobic TMSS was immobilized on them. A small amount of coexisting water promoted this immobilization process. In addition, the electroless deposition time had significant influence on the wettability of Ni–B films because micro- and nanometre-sized roughness was developed with the prolonged electroless deposition time. The superhydrophobic Ni–B films continuously repelled running water, and superhydrophobicity was maintained after rubbing them with bare fingers.
    Journal of Materials Chemistry 09/2011; 21(38):14890-14896. · 5.97 Impact Factor
  • Hitoshi Ogihara, Jun Okagaki, Tetsuo Saji
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    ABSTRACT: Superhydrophobic coatings were prepared by spraying a pigment nanoparticle suspension. By changing the type of pigment nanoparticles, the colors of the coating could be controlled. The particle size of the pigments, which determines the surface structure of the coatings, played an important role in exhibiting superhydrophobicity. The spray-coating process is applicable to a variety of materials (e.g., copper, glass, paper, coiled wire, and tied thread), and the superhydrophobicity was repairable.
    Langmuir 07/2011; 27(15):9069-72. · 4.38 Impact Factor
  • Hitoshi Ogihara, Masaru Fukasawa, Tetsuo Saji
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    ABSTRACT: We report an interesting approach for preparing micropatternings of nanomaterials, such as carbon nanotubes and TiO(2) nanoparticles. In the method, exfoliation of electrodeposited Ni thin films was the key process. After patterning indium thin oxide (ITO) plates with an insulating photoresist by conventional photolithography, Ni was electrodeposited on only the exposed ITO areas. The resulting substrates were evenly covered with nanomaterials by a drop cast method. By exfoliating the electrodeposited Ni thin films from the substrates, patterned nanomaterial films were formed.
    ACS Applied Materials & Interfaces 06/2011; 3(6):2108-11. · 5.01 Impact Factor
  • Hitoshi Ogihara, Masaru Fukasawa, Tetsuo Saji
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    ABSTRACT: A simple wet-deposition method for preparing patterned carbon nanotube (CNT) thin films is reported. Using electrophoretic deposition (EPD), CNTs were deposited over indium tin oxide (ITO) plates that had been patterned with a photoresist; consequently, CNTs covered not only the exposed ITO areas but also the photoresist areas because thinness of the photoresists could not prevent the transverse deposition of CNTs over the photoresist areas. The ultrasonic treatment for the samples removed only CNTs on the photoresist areas, resulting in the formation of patterned CNT thin films, because Ni metal formed during EPD connects CNTs to ITO plates.
    Carbon. 01/2011; 49(13):4604-4607.
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    ABSTRACT: The absorption spectra of copper phthalocyanine (CuPc) 1,2-dichloroethane (DCE) solutions containing trifluoroacetic acid (TFAA) shows that the number of protons coordinating to the CuPc molecule was 1 and 2 for the first and second proton adducts, respectively, which indicates the formations of CuPcH(+) and CuPcH(2)(2+). This CuPc molecule may act as a catalyst to dissociate TFAA into trifluoroacetate anion (A(-)) and H(+) and form the proton adducts. The electrical conductivity dependence of the solution on CuPc concentration also supports this mechanism. A dense film of CuPc was deposited on an indium tin oxide cathode plate by electrophoresis of the solution. Similar dense films of a wide variety of phthalocyanines (MPc; M = Cu, H(2), Fe, Ni, Zn, Pb, VO) were also deposited using this method. Similar films of CuPc were also formed using dichloromethane (DCM) and 1,1,1-trichloroethane (TCE) in place of DCE. Depositions are ascribed to the migration of positively charged monomers (i.e., protonated MPc). Scanning electron microscopy revealed that these films are composed of fibrous crystallites, size of which was found to increase with the electrophoresis time, the strength of the applied electrical field and the concentration of CuPc in the bath. The influence of the dielectric constant of the organic solvent on the film growth is discussed.
    Langmuir 10/2010; 26(22):17024-7. · 4.38 Impact Factor
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    ABSTRACT: Nano-scale hydroxyapatite particle network with uniform morphology and good crystallinity was fabricated on silica fiber by using carbon nanofibers as templates and with a methanol solution of Ca(NO3)2 x 4H2O-H3PO4. Field emission scanning electron microscopy, coupled with X-ray diffraction analysis confirmed the template effect and the existence of hydroxyapatite on silica fiber. It was clearly verified that by tuning the formation of carbon nanofibers on silica fiber, it was possible to control the properties of the resulting hydroxyapatite on silica fiber. In addition, the formation mechanism of hydroxyapatite on silica fiber via the template route was proposed.
    Journal of Nanoscience and Nanotechnology 08/2010; 10(8):5431-6. · 1.15 Impact Factor
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    ABSTRACT: Ni-B/diamond composite coatings were prepared using electrophoretic deposition and electroless deposition methods, leading to extremely high hardness which is comparable to hard coatings prepared by dry processes.
    Chemical Communications 01/2010; 46(3):442-4. · 6.38 Impact Factor
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    ABSTRACT: The immobilization of nanofibrous A- or B-site substituted LaMnO3 perovskite-type oxides on macroscopic silica fiber via a unique and facile carbon nanofibers (CNFs) template-based method was reported. Field emission scanning electron microscopy (FE-SEM), coupled with X-ray diffraction (XRD) analysis confirmed the template effect and the existence of nanofibrous materials immobilized on silica fiber.
    Materials Research Bulletin - MATER RES BULL. 01/2010; 45(9):1330-1333.
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    ABSTRACT: Mono and binary transition metal oxide nanotubes could be synthesized by the immersion of carbon nanofiber templates into metal nitrate solutions and removal of the templates by heat treatment in air. The transition metal oxide nanotubes were composed of nano-crystallites of metal oxides. The functional groups on the carbon nanofiber templates were essential for the coating of these templates: they acted as adsorption sites for the metal nitrates, ensuring a uniform metal oxide coating. During the removal of the carbon nanofiber templates by calcination in air, the metal oxide coatings promoted the combustion reaction between the carbon nanofibers and oxygen.
    Journal of Solid State Chemistry 06/2009; 182(6):1587–1592. · 2.04 Impact Factor
  • Hitoshi Ogihara, Jun Okagaki, Tetsuo Saji
    Chemistry Letters - CHEM LETT. 01/2009; 38(2):132-133.
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    Journal of The Surface Finishing Society of Japan 01/2009; 60(7):448-452.
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    Wataru Ueda, Masahiro Sadakane, Hitoshi Ogihara
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    ABSTRACT: New crystalline solid materials of Mo3VOx having high-dimensional structures were synthesized in a single crystalline form using a hydrothermal method where the essential structural unit in the structure already presents in the preparative solution and the fundamental structure of Mo3VOx is formed as a result of self-organization between negatively charged pentagonal units and VO2+ cations. We also synthesized metal oxides by using organic solids with particular shapes as templates in order to create nano-macrostructures. Three-dimensionally ordered macroporous (3DOM) materials of polycrystalline spinel- and perovskite-type materials were fabricated using a colloidal crystal template method in extremely high yield. In the synthesis of oxide nanotubes, we demonstrate that various oxide nanotubes could be synthesized by the adsorption and hydrolysis of precursors on the surface of carbon nanofiber templates and by the oxidative removal of templates. A variety of oxide nanotubes such as thick, thin, and helical nanotubes reflecting the shapes of carbon nanofibers could be synthesized.
    Catalysis Today. 01/2008;
  • Chemistry Letters - CHEM LETT. 01/2008; 37(8):868-869.

Publication Stats

108 Citations
82.89 Total Impact Points

Institutions

  • 1970–2014
    • Tokyo Institute of Technology
      • • Department of Chemistry and Materials Science
      • • Department of Applied Chemistry
      Edo, Tōkyō, Japan
  • 2006–2010
    • Hokkaido University
      • Catalysis Research Center
      Sapporo-shi, Hokkaido, Japan