Faculty Profiles - NAKANISHI Kazuki

Papers - NAKANISHI Kazuki

Division display 41 - 60 of about 412 ／ All the affair displays >>

Porous methylsiloxane gel thick film for millimeter-wave antenna substrate prepared by gap filling method Reviewed

Tanaka T., Kawakami N., Hirano T., Fukumoto Y., Suzuki T., Kanamori K., Nakanishi K.

Materials Research Society Symposium Proceedings Vol. 888 page： 251 - 256 2006.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Research Society Symposium Proceedings

A novel process to fabricate a thick silica gel film on an aluminum substrate, named the "gap filling method", has been developed. The process is based on a sol-gel method accompanied by phase separation in a submillimeter thick space defined by two facing substrates. Dielectric thick film integrated on a metal ground plate is successfully formed by using a SiO2 coated aluminum substrate and a cap plate covered with an amorphous carbon thin film, which control the hydrophilicity and the hydrophobicity of the plates, respectively. A thin continuous layer of less than 0. 5n thick is formed at the interface between the porous film and the cap plate, which gives the film a smooth surface preferable for patterning metal circuits of an antenna. The observed dielectric constants (εr) at 60 GHz measured by the Fabry-Perot resonator method are in the range between 1.4 and 1.6. Methyl groups homogeneously distributed in the siloxane network give a hydrophobic siloxane gel film, thus the obtained films have enough environmental stability. These results show that the gap filling method is applicable to the preparation of the porous thick film that is needed for antenna applications. © 2006 Materials Research Society.

Scopus

New macroporous crosslinked polymer gels prepared via living radical polymerization Reviewed

Kanamori K., Nakanishi K., Hanada T.

Materials Research Society Symposium Proceedings Vol. 947 page： 66 - 71 2006

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Research Society Symposium Proceedings

Macroporous crosslinked polymer gels have been prepared via TEMPO-mediated living radical polymerization of divinylbenzene (DVB) in a solvent with a counter polymer. Incorporating a counter polymer, poly(dimethylsiloxane) (PDMS), induced macroscopic spinodal-type phase separation during the course of polymerization of DVB while suppressing the segregation of DVB-derived particles from the solution by living polymerization. Well-defined macroporous morphologies comprising continuous DVB-derived skeletons have thus obtained. Macropore volume and diameter were independently controlled by altering the concentrations of PDMS and the solvent. Since the present polymer gels are prepared using only the multifunctional "crosslinker", mechanical durability against bending and compression was found to be as high as inorganic ceramics with similar morphologies and porosities. © 2007 Materials Research Society.

DOI： 10.1557/proc-0947-a03-27

Scopus

Monolithic O/I-hybrids with hierarchically ordered meso- And macropores Reviewed

Nakanishi K., Kobayashi Y., Amatani T., Hirao K., Kodaira T.

Materials Research Society Symposium Proceedings Vol. 847 page： 147 - 157 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Research Society Symposium Proceedings

Organic-Inorganic hybrid gels with hierarchical well-defined macropores and supramolecularly templated mesopores with long-range orders have been synthesized in the systems of bridged poly(silsesquioxane) systems. Nonionic surfactants such as poly(ethyleneglycol)-poly(propyleneglycol)- poly(ethyleneglycol) triblock copolymers, EOPOEOs, were found to be effective both in inducing the phase separation to give macroporous morphology and in templating the mesopores with narrow size distribution. The number of methylene units in the bridge, changed from 1 to 6 in the present experiments, affected both the phase separation tendency and template strength. In the system containing 1,2-bis(trimethoxysilyl)ethane, 2D-hexagonal arrangement of mesopores have been prepared in the gel skeleton comprising the well-defined continuous macroporous network with an aid of micelle-stabilizing agent. © 2005 Materials Research Society.

Scopus

Hierarchical macro-mesoporous silica monolith Reviewed

Amatani T., Nakanishi K., Hirao K., Kodaira T.

Materials Research Society Symposium Proceedings Vol. 847 page： 121 - 126 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Research Society Symposium Proceedings

Monolithic pure silica gels with hierarchical macro-mesoporous structure have been synthesized via spontaneous sol-gel process from silicon alkoxidc using a structure-directing agent and a micelle-swelling agent. Monolithic body with well-defined co-continuous macropores is a result of concurrent phase separation and sol-gel transition induced by the polymerization reaction, whereas the mesopores are templated by the cooperative self-assembly of inorganic species, a structure-directing agent and a micelle-swelling agent. The following removal of surfactants by heat-treatment gives silica gels with hierarchical and fully accessible pores in discrete size ranges of micrometers and nanometers. The highly ordered 2D-hexagonal arrays of mesopores have been confirmed by X-ray diffraction measurements and FE-SEM observations. Furthermore, by further additions of the micelle-swelling agent, the mesostructural transition from well-ordered 2D-hexagonal arrays to mesostructured cellular foams (MCF) have been induced accompanied by minor modifications of the micrometer-range structure. © 2005 Materials Research Society.

Scopus

Three dimensional structure and liquid transport behavior or siloxane gels with co-continuous macropores Reviewed

Saito H., Nakanishi K., Hirao K., Jinnai H., Morisato K., Minakuchi H.

Materials Research Society Symposium Proceedings Vol. 847 page： 203 - 208 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Research Society Symposium Proceedings

The geometrical properties of co-continuous macroporous silica monoliths have been studied by laser scanning confocal microscopy (LSCM) and a comparison with mercury intrusion method has been made. From three-dimensional images obtained by LSCM observation, probability density distributions of curvatures have been calculated on gel skeleton surface by the "sectioning and fitting method". Measured liquid transport behavior in macroporous siloxane gels has been related to the obtained curvature distributions. © 2005 Materials Research Society.

Scopus

Living radical polymerization in ruthenium-bearing size-exclusion silica gel column reactors Reviewed

Katsube M., Ando T., Ouchi M., Sawamoto M., Nakanishi K., Ishizuka N.

Polymer Preprints, Japan Vol. 54 ( 2 ) 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Polymer Preprints, Japan

A catalyst corresponding to Ru(Ind)Cl(PPh3)2 was covalently supported onto a mesopore and silica-gel (Chromolith™) to construct a "size-exclusion column reactor" in which "physical control" of polymer molecular weight is expected by the retention-time difference of each mobile substrate according to its size exclusion (Scheme 2). With Ru(II)-catalyzed living radical polymerization continuously performed in this column, better reaction control is expected by not only the supported catalyst but by this column separation (Fig. 1). The Ru-bearing column 5 (powder form) in fact induced living radical polymerization of methyl methacrylate with initiator 6 and an additive (n-Bu2NH) in toluene at 80°C (Fig. 2). Continuous flow polymerization in the column reactor will be discussed and compared with those in batch systems.

Scopus

Real space observation of phase separating structure in a sol-gel system Reviewed

Saito H., Kanamori K., Nakanishi K., Hirao K., Nishikawa Y., Jinnai H.

Polymer Preprints, Japan Vol. 54 ( 1 ) 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Polymer Preprints, Japan

In a sol-gel system accompanied by phase separation, co-continuous macroporous silica gels have been obtained with interconnected gel skeleton and well-defined macropores. The exact formation mechanism of the co-continuous structure, however, has not been sufficiently elucidated in a silica sol-gel system, due to the difficulty of observation in real space. After a device for preferential distribution of marker dye in gel phase and an adjustment of refractive indices between gel and solvent phases, time evolution of phase separating structure has been observed by laser scanning confocal microscopy and the detailed examination of the phase separation mechanism in a sol-gel system has been attempted.

Scopus

Real space observation of phase separating structure in a sol-gel system Reviewed

Saito H., Kanamori K., Nakanishi K., Hirao K., Nishikawa Y., Jinnai H.

Polymer Preprints, Japan Vol. 54 ( 2 ) page： 3512 - 3513 2005.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Polymer Preprints, Japan

In a sol-gel system accompanied by phase separation, co-continuous macroporous silica has been obtained, and it has been attracting attention as an efficient separation medium in a field of high performance liquid chromatography. The exact formation mechanism of the co-continuous structure, on the other hand, has been still poorly understood due to the difficulty of observation in real space. After the introduction of preferentially distributing marker dye in gel phase and the adjustment of refractive index between gel and solvent phases, time evolution of phase separating structure in a sol-gel system was observed by laser scanning confocal microscope and detailed examination of competitive kinetics between phase separation and sol-gel transition was attempted.

Scopus

Experimental validation of the tetrahedral skeleton model pressure drop correlation for silica monoliths and the influence of column heterogeneity Reviewed

N Vervoort, H Saito, K Nakanishi, G Desmet

ANALYTICAL CHEMISTRY Vol. 77 ( 13 ) page： 3986 - 3992 2005.7

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

This paper describes the use of computational fluid dynamics for the calculation of the flow resistance through computer-generated models resembling silica monoliths. This study was undertaken to determine the effect of skeleton heterogeneity on the flow resistance and, more precisely, to test the hypothesis that increased skeleton heterogeneity decreases the flow resistance. To evaluate the proposed model, 24 real silica monoliths have been prepared using the same method, covering a wide range of skeleton sizes (2.2 mu m < d(s) < 8 mu m) and porosities (0.47 < epsilon < 0.66). The permeability of these monoliths was determined by pressure drop measurements, and structural information was obtained by image analysis of laser scanning confocal microscopy-generated 3D images of the skeleton structure. The results indicate that the presence of preferential flow paths due to an increased heterogeneity of the flow through pore space reduces the flow resistance of monolithic media. It is also shown that the pore size is hence a much better suited scaling dimension than the skeleton size to reduce the permeability of monolithic columns.

DOI： 10.1021/ac0502798

Three dimensional structure and liquid transport behavior of siloxane gels with co-continuous macropores Reviewed

H Saito, K Nakanishi, K Hirao, H Jinnai, K Morisato, H Minakuchi

Organic/Inorganic Hybrid Materials-2004 Vol. 847 page： 203 - 208 2005

Language：English Publishing type：Research paper (scientific journal) Publisher：MATERIALS RESEARCH SOCIETY

Web of Science

Scopus

researchmap

Morphological Control and Mechanical Properties of Porous Phenolic Resins Derived from Poly(4‐Vinylphenol): Effects of Molecular Weight and Polydispersity of Prepolymer Reviewed

George Hasegawa, Atsushi Takano, Chika Hiei, Kyoka Kusano, Kazuki Nakanishi

Advanced Engineering Materials Vol. 26 ( 21 ) 2024.11

Crystalline organic monoliths with bicontinuous porosity Reviewed

Naoto Matsumoto, Sakura Nakagawa, Kei Morisato, Kazuyoshi Kanamori, Kazuki Nakanishi, Nobuhiro Yanai

Chemical Science Vol. 15 ( 29 ) page： 11500 - 11506 2024.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Royal Society of Chemistry (RSC)

Crystalline organic monoliths (COMs) are a novel class of monolithic materials with a bicontinuous porous structure composed of photo-functional molecular crystals.

DOI： 10.1039/d4sc01650e

Hydrogarnet-Derived Porous Polyhedral Particles of SrFeO<sub>3-δ</sub> Perovskite Reviewed

Hikaru Otaguro, Tomoki Takeno, Ryosuke Sugimoto, Saburo Hosokawa, Hirofumi Akamatsu, Takahisa Yamamoto, Kazuki Nakanishi, Katsuro Hayashi, George Hasegawa

Chemistry of Materials Vol. 35 ( 16 ) page： 6423 - 6436 2023.8

Preparation of Hierarchically Porous Niobium(V) Oxide and Alkaline Niobate Monoliths via Sol–Gel Accompanied by Phase Separation Reviewed

Yuji Sato, Kazuyoshi Kanamori, Kazuki Nakanishi

Chemistry of Materials Vol. 35 ( 13 ) page： 5177 - 5184 2023.6

Fabrication process development and basic evaluation of eggshell-based column packing material for reversed-phase preparative separation Reviewed

Tomoka Yoshii, Akihiro Sakama, Kazuyoshi Kanamori, Kazuki Nakanishi, Hiroaki Imai, Daniel Citterio, Yuki Hiruta

Journal of Chromatography A Vol. 1688 page： 463722 2023.1

Mechanical and thermal properties of porous polyimide monoliths crosslinked with aromatic and aliphatic triamines Reviewed

Mitsuhiro Ishida, Yutaro Sashiyama, Hirofumi Akamatsu, Katsuro Hayashi, Kazuki Nakanishi, George Hasegawa

Journal of Sol-Gel Science and Technology Vol. 104 ( 3 ) page： 526 - 535 2022.12

Amphiphilic Copolymer-Modified Eggshell-Based Column Packing Materials for the Preparative Separation of Basic Drugs Reviewed

Yoshii T., Mochida M., Kaizu K., Soda Y., Kanamori K., Nakanishi K., Sato T., Imai H., Citterio D., Hiruta Y.

ACS Applied Polymer Materials Vol. 4 ( 10 ) page： 6949 - 6957 2022.10

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Applied Polymer Materials

A way to utilize eggshells is desired because most of the eggshell waste is disposed of in landfills. Despite eggshells having attractive features such as a thermodynamically stable porous crystalline structure, their effective utilization as a functional material has yet to be demonstrated. Herein, we developed an alkali-stable column packing material for reversed-phase preparative high-performance liquid chromatography (HPLC) based on eggshells. Nanocrystals and biopolymers present on eggshell powder were removed by surface treatment with buffered ethylenediaminetetraacetic acid (EDTA) and sodium hypochlorite solutions, resulting in bare calcium carbonate with a uniform porous surface. The obtained particles were modified with poly(maleic acid-alt-1-octadecene) (PMAcO) having hydrophobic alkyl chains and anionic carboxylate groups. The prepared PMAcO-modified eggshell-based material was applied to an HPLC column, and its performance is evaluated. The column succeeded in the separation of alkylbenzenes, steroids, and diastereomers. It was also used for the separation of basic tricyclic antidepressants in an alkaline mobile phase, showing excellent retention capacity and alkali stability. This study demonstrates the potential of eggshell utilization, providing not only a practical stationary phase for HPLC but also a solution for recycling calcium carbonate-based biomineral waste.

DOI： 10.1021/acsapm.2c00866

Scopus

Oxide-on-Oxide Porous Electrodes Revealing Superior Reversible Li<sup>+</sup>-Coupled Electron-Transfer Properties by Unconventional Heterojunction Effects Reviewed

Yosuke Hara, Rikuo Shigetake, Kazuki Nakanishi, Kazuyoshi Kanamori, Ken Sakaushi

ACS Applied Materials & Interfaces Vol. 14 ( 31 ) page： 35883 - 35893 2022.7

Designing hierarchical porosity in tin oxide monoliths and their application as a solid acid catalyst Reviewed

Yoshinao Suzuki, George Hasegawa, Kazuyoshi Kanamori, Kazuki Nakanishi

New Journal of Chemistry Vol. 45 ( 37 ) page： 17558 - 17565 2021.10

Sol–gel based structural designs of macropores and material shapes of metal–organic framework gels Reviewed

Yosuke Hara, Kohei Manabe, Kazuki Nakanishi, Kazuyoshi Kanamori

Materials Advances Vol. 2 ( 13 ) page： 4235 - 4239 2021.7

　 PREV - NEXT 　

<NAKANISHI Kazuki>

Papers - NAKANISHI Kazuki