受賞国：アメリカ合衆国

受賞区分：国際学会・会議・シンポジウム等の賞  受賞国：アメリカ合衆国

Outstanding contributions to sol-gel science and technology through broad and productive scholarship; by achievements in commercial and industrial applications of sol-gel science and technology; and/or by outstanding service to the sol-gel community that has been sustained over an entire career

researchmap

受賞区分：国内学会・会議・シンポジウム等の賞  受賞国：日本国

researchmap

researchmap

researchmap

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

DOI： 10.1007/s10971-022-05955-1

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Ceramic Society  

Porous nonoxide ceramics have exhibited impressive progress in terms of synthesis and applications over the past few decades because of their unique characteristics distinguished from the oxide counterparts. From the synthetic aspect, the preceramic polymer route, where nonoxide ceramics such as carbides and nitrides are produced from molecular precursors, offers exceptional opportunities to elaborate and control the material shape as well as the micro- and nanostructures in concert with various techniques. This review presents monolithic ceramic materials based on various reduced phases bearing hierarchical porosity with a focus on those obtained from macroporous preceramic monoliths prepared via the one-pot sol–gel process accompanied by spinodal decomposition. Here, we highlight two classes of preceramic inorganic–organic hybrid gels: organometallic crosslinked polymers based on poly(silsesquioxane)s and nonorganometallic hybrid networks related to Ti without Ti–C bonds. The polymer-to-ceramic conversion processes are discussed with concern for the crystal transition behaviors and the variation of pore properties in different length scales upon heating. In addition, although out of the preceramic polymer category, some examples of inorganic–organic nanocomposite gels with a carbonizable polymer and/or urea for yielding porous metal carbides and nitrides in a monolithic form are introduced as well, which provides extended versatility toward a variety of transition metal systems.

DOI： 10.1111/jace.18130

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Frontiers in Chemical Engineering  

The sol–gel process accompanied by phase separation is one of the methods to prepare hierarchically porous monoliths, hierarchically porous monolith, which is applicable not only to oxides but also to various materials compositions such as metal phosphates, organic-polymers/carbons, metal-organic frameworks. It is not until recently, however, that progress has been made in the preparation of low-valence metal oxide HPMs, such as those of magnesium, manganese, cobalt, nickel, etc. Due to the difficulty of divalent metal precursors to form homogeneous gels, different approaches from those established for trivalent and tetravalent counterparts have been attempted. This short review introduces the methods and trials in the preparation of metal oxide HPMs from divalent metal salts.

DOI： 10.3389/fceng.2021.787788

Web of Science

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

A wide-range control over multimodal pore systems in porous monoliths is a key technology for developing functional materials, as the favorable pore structures in different length scales are required to be tailored depending on their application fields. In the alkoxy-derived sol–gel systems of silica and organosilicates, the synthetic methodology of meso- and macroporous monoliths with tunable pore properties has been developed by combining the supramolecular self-assembly of a Pluronic surfactant and polymerization-induced phase-separation techniques. This strategy has been applied to the sol–gel process of phenolic resins, giving rise to the hierarchically porous polymer gels with ordered mesoporosity and the corresponding carbon monoliths after carbonization. However, the controllable size range has been limited so far. This study has explored the relationship between the starting composition and the bimodal pore properties in further detail aiming at a better control of pore properties in phenolic resins. The enlargement of mesopore size has been achieved, yet associated with broadening the mesopore size distribution and coarsening the macropore morphology, resulting in the particle aggregates. The systematical investigation also reveals that the addition of KCl can improve the micelle arrangement in macroframework and provide the narrower mesopore size distribution. [Figure not available: see fulltext.]

DOI： 10.1007/s10971-020-05236-9

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1002/ange.201911499

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Langmuir  

Free-standing electrodes, which are free from additives (binders and conductive agents) and even current collectors, are useful in terms of both application research and fundamental study. Here, we demonstrate the preparation of binder-free monolithic carbon electrodes embracing Si nanoparticles in their well-defined porous scaffolds via the one-pot sol-gel reaction followed by carbonization. The free-standing electrodes with a thickness of 150 μm work out as a high-areal-density anode for Li-ion batteries, delivering up to ca. 7 mA h cm-2. As the Si content increases, the capacity decay on cycling becomes pronounced, which is likely to associate with the fracturing and pulverization of Si nanoparticles even with the size smaller than 100 nm after long-term cycles. The thermogravimetry-mass spectrometry profile of the cycled electrode corroborates the successive electrolyte decomposition to grow solid electrolyte interphase (SEI) mainly composed of lithium alkylcarbonates, polymeric species, and LiF, rendering the electrode mass nearly double of its original state after 200 cycles. The elemental mapping analysis reveals that LiF is generated inhomogeneously in the monolithic electrodes unlike the other SEI components, resulting in the concentration gradient depending on the distance from a Li counter electrode.

DOI： 10.1021/acs.langmuir.9b02085

Web of Science

Scopus

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Angewandte Chemie - International Edition  

Aerogels are porous materials but show poor mechanical properties and limited functionality, which significantly restrict their practical applications. Preparation of highly bendable and processable aerogels with multifunctionality remains a challenge. Herein we report unprecedented superflexible aerogels based on polyvinylpolydimethylsiloxane (PVPDMS) networks, PVPDMS/polyvinylpolymethylsiloxane (PVPMS) copolymer networks, and PVPDMS/PVPMS/graphene nanocomposites by a facile radical polymerization/hydrolytic polycondensation strategy and ambient pressure drying or freeze drying. The aerogels have a doubly cross-linked organic–inorganic network structure consisting of flexible polydimethylsiloxanes and hydrocarbon chains with tunable cross-linking density, tunable pore size and bulk density. They have a high hydrophobicity and superflexibility and combine selective absorption, efficient separation of oil and water, thermal superinsulation, and strain sensing.

DOI： 10.1002/anie.201804559

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wiley  

DOI： 10.1002/ange.201804559

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Non-Crystalline Solids  

Ambient pressure drying of polymethylsilsesquioxane gels via dynamic shrinkage-reexpansion has been investigated for preparation of aerogel-like xerogels and their application to thermal superinsulators. An extended aging of wet gels in aqueous solution containing precursor-derived species is found to be crucial in obtaining crack-free, monolithic xerogels with sufficiently low thermal conductivity (13.7 mW m- 1 K- 1) at bulk density of 0.140 g cm- 3 (porosity - 90%).

DOI： 10.1016/j.jnoncrysol.2015.12.016

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Chemical Society  

Inspired by homogeneous borane catalysts that promote Si-H bond activation, we herein describe an innovative method for surface modification of silica using hydrosilanes as the modification precursor and tris(pentafluorophenyl) borane (B(C6F5)3) as the catalyst. Since the surface modification reaction between surface silanol and hydrosilane is dehydrogenative, progress and termination of the reaction can easily be confirmed by the naked eye. This new metal-free process can be performed at room temperature and requires less than 5 min to complete. Hydrosilanes bearing a range of functional groups, including alcohols and carboxylic acids, have been immobilized by this method. An excellent preservation of delicate functional groups, which are otherwise decomposed in other methods, makes this methodology appealing for versatile applications. © 2014 American Chemical Society.

DOI： 10.1021/ja504115d

Web of Science

Scopus

PubMed

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Angewandte Chemie - International Edition  

A monolithic material has marshmallow-like flexibility and superamphiphobic properties on any cutting surface. The two-step synthesis consists of a simple sol-gel process to obtain vinyl-modified superhydrophobic monolithic gels and grafting of perfluoroalkyl groups onto the pore surface to decrease surface energy. These superamphiphobic materials float on water and even on organic liquids with low polarity, such as alkanes. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/anie.201304169

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Angewandte Chemie - International Edition  

Soaking up s'more: Marshmallow-like flexible gels synthesized from organoalkoxysilanes by a facile process show superior oil/water separation properties. The gels are superhydrophobic and can be used to remove organic compounds from water through absorption; they can then be recovered by squeezing them out of the gel, as if it were a sponge. The gel retains flexibility over a wide temperature range, even in liquid nitrogen (see photo). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/anie.201207969

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Chemical Society  

Monolithic conductive titanium oxides Ti nO 2n-1 (n = 2, 3, 4, 6) with well-defined macropores have been successfully prepared as a single phase, via reduction of a macroporous TiO 2 precursor monolith using zirconium getter. Despite substantial removal of oxide ions, all the reduced monoliths retain the macropore properties of the precursor, i.e., uniform pore size distribution and pore volume. Furthermore, compared to commercial porous Ebonex (shaped conductive Ti nO 2n-1), the bulk densities (1.8 g cm -3) are half, and the porosities (60%) are about 3 times higher. The obtained Ti nO 2n-1 (n = 2, 3, 4, 6) macroporous monoliths could find applications as electrodes for many electrochemical reactions. © 2012 American Chemical Society.

DOI： 10.1021/ja302083n

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemical Society Reviews  

Porous polysilsesquioxane gels derived from sol–gel systems based on trifunctional silanes are reviewed. Although it is well known that trifunctional silanes possess inherent difficulties in forming homogeneous gels, increasing attention is being paid on these precursors and resultant porous polysilsesquioxanes because of hydrophobicity, functionality, and versatile mechanical properties. Much effort has been made to overcome the difficulties for homogeneous gelation, and a number of excellent porous materials with various pore properties have been explored. In this critical review, we put special emphasis on the formation of a well-defined macroporous structure by making use of phase separation, which in turn is a serious problem in obtaining homogeneous gels though. Porous polysilsesquioxane monoliths with the hierarchical structure and transparent aerogels with high mechanical durability are particularly highlighted (169 references). © 2011 The Royal Society of Chemistry.

DOI： 10.1039/c0cs00068j

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Ceramic Society  

Monolithic titania (TiO2) with multiscale porous structures have been successfully prepared via the sol-gel route accompanied by phase separation utilizing a chelating agent and mineral salt. The TiO2 gels obtained possess well-defined macropores derived from spinodal decomposition and mesopores as interstices of anatase TiO2 nanocrystallites.Most of the chelating agent were removed by hydrolysis and subsequent decarbonation through the gradual solvent exchange from ethanol to water. The TiO2 particles comprising TiO2 gel skeletons spontaneously converted from amorphous to anatase through the solvent exchange process in a mild condition at 60°C. The present method of the fabrication of porous TiO2 monoliths is advantageous for widespread applications because the reaction occurs under an almost neutral condition and does not require a hydrothermal process, which was indispensable to strengthen the monolith in the method previously reported © 2010 The American Ceramic Society.

DOI： 10.1111/j.1551-2916.2010.03831.x

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Society Symposium Proceedings  

In various crosslinking systems containing metal oxides, organo-siloxane polymers and pure hydrocarbons, monolithic materials with hierarchical well-defined macropores and controlled mesopores have been synthesized. Synthetic progress in alkoxy-derived macroporous silica lead to the preparation of long-range ordered mesoporous skeletons in well-defined macroporous framework. Alkylene-bridged silicon alkoxides can also be prepared into similarly hierarchical porous structures with broadened variations in framework morphology. Macro-mesoporous alkoxy-derived pure titania and zirconia have been prepared using hydrochloric acid - mediated processes. Compared with those prepared from colloidal dispersions, alkoxy-derived macroporous titania exhibited much higher mechanical strength. Titania monolith is a promising candidate as a separation medium to discriminate phosphorylated compounds in a liquid chromatography mode. Pure alumina macroporous monolith has been first synthesized from aluminum salt using propylene glycol as a proton scavenger to thrust the solution pH from acidic into neutral conditions. Alumina-based complex oxides such as garnets and spinels can also be prepared in pure phases. Polymerization and phase separation in organic crosslinker system was also controlled to obtain well-defined co-continuous macro-frameworks instead of those composed of aggregated particles. These examples demonstrate the versatility of using phase-separation in gelling systems to obtain well-defined macroporous structures. © 2007 Materials Research Society.

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Society Symposium Proceedings  

By inducing phase separation parallel to the sol-gel transition of alkoxy-derived silica systems, gels having both macroporous and mesoporous structures can be obtained. Using poly(acrylamide) (PAAm) as a phase-separation inducer, macro/mesoporous silica gels were synthesized. After solvent exchange by water, the size distribution of mesopores of wet gels was evaluated by thermoporometry using a differential scanning calorimetry (DSC). Alternatively, gels were evaporation-dried after solvent exchange by ethanol or water/ethanol, followed by heat-treatment to completely remove volatile and organic components. Characterization of the dried or heat-treated samples was carried out using a scanning electron microscope (SEM) and by nitrogen adsorption measurements. Experimental results showed that the interaction between PAAm and silica is not so strong as the case of polymers having poly(oxyethylene) chains. The contribution of the secondary phase separation within the crosslinking silica-rich phase was suggested to be responsible for the mesopore formation in the PAAm-silica system. © 2007 Materials Research Society.

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Society Symposium Proceedings  

Pure alumina monoliths with well-defined macropores and mesostructured skeleton have been synthesized via a spontaneous route from the aqueous and ethanolic solution of aluminum salts in the presence of propylene oxide and high molecular weight poly(ethylene oxide)(PEO). The addition of propylene oxide to the starting solution controls the gelation, while the addition of PEO induces the phase separation. Appropriate choice of the starting composition, with which the phase separation and gelation concur, produces large-dimension (10mm×10mm×10mm), bicontinuous macroporous Al2O 3 monoliths. The mean size of the continuously connected pores is controlled in the micrometer range, depending on the PEO concentration and polarity of the solution. On the other hand, micropores and mesopores, originated from the interstices among primary particles, exhibit median pore size of about 2.6 nm and the BET surface area as high as 396 m2/g after dried temperature at 40°C. © 2007 Materials Research Society.

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Society Symposium Proceedings  

Macroporous cross-linked polymeric dried gels have been obtained by inducing phase separation in a homogeneous poly(divinylbenzene) (PDVB) network formed by organotellurium-mediated living radical polymerization (TERP). The living polymerization reaction of DVB with the coexistence of a non-reactive polymeric agent, poly(dimethylsiloxane) (PDMS), in solvent 1,3,5- trimethylbenzene (TMB) resulted in polymerization-induced phase separation (spinodal decomposition), and the transient structure of spinodal decomposition has been frozen by gelation. Well-defined macroporous monolithic dried gels with bicontinuous structure in the micrometer scale are obtained after removing PDMS and TMB by simple washing and drying. The properties of the macropores have been controlled by changing starting composition. © 2009 Materials Research Society.

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Research Society Symposium Proceedings  

Transparent organic-inorganic hybrid aerogels and aerogel-like xerogels have been prepared from methyltrimethoxysilane (MTMS) respectively by supercritical drying (SCD) and ambient pressure drying (APD). The new aerogels and xerogels significantly deform without collapsing on uniaxial compression and almost fully relax when unloaded. This elastic behavior, termed as "spring-back", allows APD without noticeable shrinkage and cracking. The flexible network composed of lower cross-linking density (up to three bonds per every silicon atom) compared to silica gels (up to four bonds) and repulsion between hydrophobic methyl groups bonded to every silicon atom largely contributes to the pronounced deformability and relaxing, respectively. Lower surface silanol group density also plays a crucial role for the "spring-back" behavior. © 2009 Materials Research Society.

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

By combining the micellar templating in nanometer-scale with the polymerization-induced phase separation in micrometer-scale, we can synthesize monolithic silica or silsesquioxane gel materials with hierarchical well-defined macropores and shape-controlled mesopores. Depending on the mechanism of enhancing micellar-templating of siloxane oligomers, macroframeworks containing long-range-ordered cylindrical mesopores with different degrees of order have been produced. Alkylene-bridged silicon alkoxides can also be prepared into similarly hierarchical porous structures with broadened variations in framework morphology. These examples demonstrate the versatility of using phase-separation in micellartemplated gelling systems to obtain well-defined macroporous structures. © 2008 American Chemical Society.

DOI： 10.1021/cm702486b

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Accounts of Chemical Research  

Sol-gel processes for fabricating oxides or metalloxane polymers with controlled porous structures have been reviewed. Gel materials having controlled macropores are synthesized by polymerization-induced phase separation and concurrent sol-gel transition in a variety of chemical compositions. Several variations of tailoring mesopore structures within the macroporous materials are introduced, which enable one to design hierarchically porous metal oxide and metalloxane polymer materials. Applications of monolithic silica gels having hierarchical macro/mesoporous structure to the separation media of high-performance liquid chromatography, HPLC, are described. © 2007 American Chemical Society.

DOI： 10.1021/ar600034p

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Materials  

Transparent hydrophobic MSQ aerogels and aerogel-like xerogels have been obtained from a single trifunctional precursor. Two kinds of surfactants were used to suppress phase separation between the hydrophobic MTMS-derived species and polar solvents. Urea acts as a polymerization accelerator to freeze the structure prior to macroscopic phase separation. Some of the obtained gels showed reversible deformation during uniaxial compression tests and thus were successfully dried by evaporation drying under ambient pressures. The obtained xerogels exhibited similar pore properties to corresponding aerogels such as high porosity and transparency. The new method may lead to lower-cost and larger-scale industrial processes, suggesting that aerogels will find increased usage in general applications such as insulators for windows and solar heat panels.

DOI： 10.1002/adma.200602457

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/ac060770e

Web of Science

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer Preprints, Japan  

This work was aimed to development of continuous-flow living radical polymerization in a silica-gel column, "Chromolith", focusing its separation function by combination of surface chemical absorption and size-exclusion via uniquely shaped mesopores, Thus, living radical copolymerization of two monomers with different polarities, methyl methacrylate (MMA) and 2(dimethylamino)ethyl methacrylate (DMAEMA) was performed with a catalyst [2; Ru(Ind)Cl(PPh3)2] coupled with an initiator (1). Copolymers were continuously produced, and molecular weight distributions were narrower than that in the corresponding batch process.

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer Preprints, Japan  

Macroporous polymer monoliths with rigid three-dimensional networks have been prepared via living radical polymerization of multi-functional vinyl crosslinkers. By incorporating a polymeric agent to effectively induce phase separation, well-defined macroporous morphology with highly interconnected gel skeletons and macropores has been formed presumably by spinodal decomposition. The pore size and volume are found to be controlled simply by changing starting compositions.

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Materials  

Monolithic rigid macroporous poly(divinylbenzene) with well-defined bicontinuous morphology was prepared by living radical polymerization. polydimethylsiloxane (PDMS) was used as a phase separator, and acetic anhydride acted as an acylating agent, resulting in the formation of a coordination bond between the methyl carbon on acetic anhydride and the lone electron pair on the alkoxyamine nitrogen. A bicontinous configuration could be observed with the dimethylsiloxane (DMS)-derived gel skeletons and macropores interconnected to form a 3D network. The study confirmed that heat treatment at 200°C does not have any influence on the macroporous morphology. It was also confirmed that the segregation of highly crosslinked particles could be prevented, and the well-defined bicontinuous structure developed by the initial SD step was preserved at the sub-micrometer scale. This method is expected to be applicable to a variety of living polymerization systems.

DOI： 10.1002/adma.200601026

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Analytical Chemistry  

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 μm < d s < 8 μm) and porosities (0.47 < ε < 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. © 2005 American Chemical Society.

DOI： 10.1021/ac0502798

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Engineering Materials  

Improvement of mechanical stability for porous polymer monoliths is one of the prime concerns as represented by the long-standing research efforts on resorcinol-formaldehyde (RF) aerogels. To this end, it is imperative not only to tailor mechanically robust porous morphology but also to design macromolecular structure of polymer scaffolds. Previously, we have developed porous RF gels showing a unique mechanical feature combining high mechanical strength and outstanding flexibility against uniaxial compression. Comparison of mechanical properties between the porous gels with varied morphologies has elucidated the influence of porous structure, whereas effects of macromolecular structure still remain elusive. Herein, we have fabricated a series of macroporous phenolic resins from three types of linear prepolymers with phenol pendant groups, poly(4-vinylphenol) or poly(4-hydroxystyrene), which differ in molecular-weight properties, by the sol–gel process in conjunction with spinodal decomposition. The difference in gelation and phase separation behaviors observed for the discrete systems indicates the dissimilar cross-linked networks developed in the respective gels, which consequently influence the mechanical strength and flexibility against uniaxial compression. This study also demonstrates the improvement of mechanical features by thermal treatment for the porous monoliths derived from the high-molecular-weight prepolymer with a view to the application in mechanical energy absorption.

DOI： 10.1002/adem.202401038

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemical Science  

Organic crystals are a promising class of materials for various optical applications. However, it has been challenging to make macroscopic organic crystals with bicontinuous porosity that are applicable to flow chemistry. In this study, a new class of porous materials, cm-scale crystalline organic monoliths (COMs) with bicontinuous porosity, are synthesized by replicating the porous structure of silica monolith templates. The COMs composed of p-terphenyl can take up more than 30 wt% of an aqueous solution, and the photophysical properties of the p-terphenyl crystals are well maintained in the COMs. The relatively high surface area of the COMs can be exploited for efficient Dexter energy transfer from triplet sensitizers on the pore surface. The resulting triplet excitons in the COMs encounter and annihilate, generating upconverted UV emission. The COMs would open a new avenue toward applications of organic crystals in flow photoreaction systems.

DOI： 10.1039/d4sc01650e

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Introduction of open mesoporosity into microparticles with a robust morphology provides a high active surface area together with good thermal stability and shows benefit in various applications at high temperatures. Recently, nonstoichiometric Sr-Fe perovskites with an oxygen release/absorption capability have attracted interests as an oxidation catalyst operated at elevated temperatures. Here, we demonstrate the topotactic synthesis approach to fabricate mesoporous microparticles of SrFeO3−δ with monodispersibility as well as rhombic dodecahedral morphology from the correspondent hydrogarnet precursor (Sr3Fe2(OH)12) prepared by the hydrothermal reaction. Relationship between synthetic conditions and the formed crystal morphology has been systematically explored, which discloses that the crystallization of hydrogarnet can take place at as low as 40 °C. On heating, the dehydration of Sr3Fe2(OH)12 gives rise to phase separation into Sr(OH)2 and SrFeO3−δ via a transient phase of “oxyhydrogarnet”. Selective removal of the Sr(OH)2-derived phase leaves three-dimensionally interconnected mesopores in individual polyhedral microparticles. Meanwhile, further increase of the heat-treatment temperature sets off the reaction between the two separated phases, ending up in nonporous polyhedral particles composed of Ruddlesden-Popper-type layered perovskite (Sr3Fe2O7−δ) at 1200 °C. The mesoporous SrFeO3−δ polyhedral microparticles exhibit an enhanced catalytic performance of CO oxidation superior to the nonporous counterparts, which is associated with the stimulated oxygen release capability owing to mesoporosity rather than the oxygen uptake rate.

DOI： 10.1021/acs.chemmater.3c01150

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Hierarchically porous niobium(V) oxide monoliths were prepared through the sol-gel process accompanied by phase separation and subsequent heat treatment. Macroporous and mesoporous characteristics as well as crystal structures were investigated in detail. Macroporous structures were controlled by the starting composition to manipulate phase separation, whereas mesoporous structures were modified by heat treatment in air to crystallize niobium(V) oxide. The results showed that by heat treating the as-dried gel at 550 °C in air, a hierarchically ordered macro/mesoporous material with BET surface area of 54 m2 g-1 was obtained. With an increase of the heat treatment temperature, an increase in the mesopore size accompanied by a decrease in the specific surface area was observed as a result of crystallite growth. Heat treatment under a N2 atmosphere resulted in the formation of phases with lower-valence niobium such as NbO2 and Nb12O29, which were derived from the reduction by the carbothermal reaction due to the presence of carbonized organic compounds. The conversion of niobium(V) oxide into niobium-containing complex oxides was also examined. Alkaline metals, namely, Li, Na, and K, were incorporated by postgelation treatments. Niobium-rich alkaline niobate phases were obtained when alkaline chloride was incorporated, whereas the majority of lithium niobate (LiNbO3) phases were obtained when samples were treated with lithium hydroxide.

DOI： 10.1021/acs.chemmater.3c00916

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

Purification of basic drugs in reversed-phase mode is often difficult, mainly due to adsorption of positively charged compounds to the silica gel-based stationary phase. Since this adsorption can be suppressed under alkaline condition, columns with alkali-resistance are required. In addition, compounds with acid-sensitive structures are sometimes degraded during separation on silica gel-based columns which exhibit acidity due to their surface structure. We prepared an alkali-resistant reversed-phase packing material, Eggshell-PMAcO based on eggshells modified with an amphiphilic copolymer, poly(maleic acid-alt-1-octadecene) (PMAcO). The height equivalent to a theoretical plate (HETP) of the Eggshell-PMAcO column was improved by surface treatment with ammonium acetate buffer (900 mM, pH = 3.7), which is an inexpensive reagent, and the retention behavior for hydrophobic compounds was compared to a typical ODS column based on silica gel, resulting in sufficient selectivity of the eggshell-based column for hydrophobic compounds, as indicated by the ratio of retention factors of pentylbenzene and butylbenzene (Eggshell-PMAcO column: 1.55, ODS column: 1.65). Column temperature-dependent retention behavior of naphthalene was investigated in the temperature range from 25 °C to 45 °C, followed by the calculation of thermodynamic parameters. There was little difference in the standard molar enthalpy (Eggshell-PMAcO: −19.6 kJ/mol, ODS: −21.7 kJ/mol). The absolute value of the standard free Gibbs energy for the Eggshell-PMAcO column was much smaller than that of the ODS column (Eggshell-PMAcO: −0.284 kJ/mol, ODS: −13.0 kJ/mol), indicating that the Eggshell-PMAcO column had a weaker retention strength for naphthalene than the ODS column mainly due to the large difference in the standard molar entropy (Eggshell-PMAcO: −64.9 J/mol K, ODS column: −29.2 J/mol K). The retention capacities for imipramine under neutral (water/methanol) and alkaline (0.1% triethylamine water/methanol) conditions were 0.2 mg and 5 mg, respectively, based on injection mass-dependent HETP, retention factor and symmetry factor. Finally, the prepared column was applied to the purification of a building block for nucleic acid drugs. This study demonstrated that reversed-phase columns, which can be fabricated from eggshells and an amphiphilic copolymer in an inexpensive and eco-friendly way, have the ability to purify basic compounds and acid-sensitive compounds.

DOI： 10.1016/j.chroma.2022.463722

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Thermal insulating materials are of importance for efficient and effective use of heat energy. Porous organic foams are widely employed for this purpose owing to their low thermal conductivity and mass productivity at low cost. However, the poor thermal stability of organic polymers limits their availability within a low temperature range (typically, < 150 °C). In this paper, we demonstrate the one-pot sol–gel synthesis of porous poly(amic acid) (PAA) xerogels and their conversion to porous polyimide (PI) monoliths by thermal imidization. The PAA networks crosslinked with either aromatic or aliphatic triamine and the bicontinuous porous morphology tailored via spinodal decomposition allow the evaporative drying at ambient pressure to obtain low-density PAA xerogels without significant shrinkage. The aromatic crosslinker yields the porous PI monoliths with higher porosity and flexible feature as compared with those prepared with the aliphatic triamine. On the other hand, the porous PI monolith based on the aliphatic crosslinker possesses slightly higher thermal stability owing to the stiffer mechanical property. The durability test results verify the porous PI thermal insulators are available in air at up to ~450 °C for a short period and up to ~350 °C for a long term. [Figure not available: see fulltext.]

DOI： 10.1007/s10971-022-05843-8

Web of Science

Scopus

researchmap

その他リンク： https://link.springer.com/article/10.1007/s10971-022-05843-8/fulltext.html

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：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

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Internal spacing of electrodes is a key point for controlling electron-transfer (ET)-related phenomena. However, their disordered porous structures often prevent the observation of microscopic effects. It hampers the development of modern electrochemical theories. The development of model porous electrodes therefore provides an ideal platform to discover intriguing fundamental principles of electrode processes. We developed a new synthetic strategy for all-oxide monolithic ruthenium dioxide (RuO2)/antimony-doped tin oxide (ATO) electrodes with a controlled hierarchically porous structure and oxide-oxide heterojunction. The use of the obtained RuO2/ATO electrodes as model electrodes suppressed influences related to different mass diffusion efficiencies between electrodes with heterojunctions of different types. Then, we showed unconventional oxide-oxide heterojunction effects, improving reversible Li+-coupled electron-transfer properties using model electrodes constituted of various nanostructured (nano-) RuO2 on porous ATO. In addition to the superior electrochemical properties of the nano-RuO2/ATO heterojunction, the quasi-two-dimensional (2D) RuO2/ATO heterojunction led to improved specific capacity at a high rate and longer cycle life. We anticipate that this oxide-oxide heterojunction effect and developed all-oxide model porous electrodes can provide a path to develop advanced reversible energy storage devices.

DOI： 10.1021/acsami.2c06297

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Hierarchically porous tin oxide monoliths have been prepared for the first time from a low-cost tin(iv) chloride precursor through an epoxide-mediated sol-gel process in an aprotic solvent N,N-dimethylformamide. Phase separation is induced in the presence of poly(propylene glycol) in the course of polymerization triggered by an acid scavenger, propylene oxide, leading to macroporous tin-based oxyhydroxide monoliths. The resultant macropores are confirmed to be controlled in the size range of 0.9-2.9 μm. Both the post-gelation solvothermal treatment in 2-propanol and calcination in air gave rise to crystallinity and mesoporosity (2.4-103 nm in size with BET surface area up to 261 m2 g-1), and hierarchically porous tin oxide monoliths have been obtained for the first time. The monoliths are demonstrated as a catalyst for the esterification of valeric acid and methanol. This journal is

DOI： 10.1039/d1nj03307g

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Advances  

We have developed a general synthetic strategy to control macroporous structures and material shapes of metal-organic framework (MOF) gels via a sol-gel based structural control process. A series of 1,3,5-benzene tricarboxylic acid (BTC) based MOF gels, Cr-BTC and Zr-BTC, have been chosen as a proof of concept.

DOI： 10.1039/d0ma01009j

Web of Science

Scopus

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Clinical and Experimental Nephrology  

Background: Pathological findings in Alport syndrome frequently show mesangial proliferation and sometimes incidental IgA deposition, in addition to unique glomerular basement membrane (GBM) changes including thin basement membrane and/or lamellation. However, similar GBM abnormalities are also often observed in IgA nephropathy. Both diseases are also known to show hematuria, proteinuria, and sometimes macrohematuria when associated with viral infection. Therefore, it can be difficult to make a differential diagnosis, even based on clinical and pathological findings. Some recent articles demonstrated that galactose-deficient IgA1 (Gd-IgA1)-specific monoclonal antibody (KM55) could potentially enable incidental IgA deposition to be distinguished from IgA nephropathy. Methods: We performed comprehensive gene screening and glomerular Gd-IgA1 and type IV collagen α5 chain immunostaining for five cases with both IgA deposition and GBM changes to confirm that Gd-IgA1 can help to distinguish these two diseases. Results: Four of the cases were genetically diagnosed with Alport syndrome (Cases 1–4) and one was IgA nephropathy with massive GBM changes, which had a negative gene test result (Case 5). In Cases 1–4, glomerular Gd-IgA1 deposition was not detected, although there was positivity for IgA in the mesangial area. In Case 5, glomerular Gd-IgA1 deposition was observed. Conclusion: Gd-IgA1 expression analysis could clearly differentiate these two disorders. This approach can be applied to identify these two diseases showing identical clinical and pathological findings.

DOI： 10.1007/s10157-021-02054-3

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advances in Mathematics  

The Cauchy problem for the Zakharov system in the energy-critical dimension d=4 is considered. We prove that global well-posedness holds in the full (non-radial) energy space for any initial data with energy and wave mass below the ground state threshold. The result is based on a Strichartz estimate for the Schrödinger equation with a potential. More precisely, a Strichartz estimate is proved to hold uniformly for any potential solving the free wave equation with mass below the ground state constraint. The key new ingredient is a bilinear (adjoint) Fourier restriction estimate for solutions of the inhomogeneous Schrödinger equation with forcing in dual endpoint Strichartz spaces.

DOI： 10.1016/j.aim.2021.107746

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Lymphatic Research and Biology  

Background: Manual lymph drainage (MLD) is one of the common treatments for breast cancer-related lymphedema (BCRL). Although the primary goal of MLD is to drain the excessive fluid accumulated in the affected upper limb and trunk to an area of the body that drains usually, the use of MLD is decided based on swelling and subjective symptoms, without assessing whether there is fluid accumulated in the affected region. The purpose of this study was to examine truncal fluid distribution in a sample of BCRL patients and investigate any correlation between such fluid distribution and swelling or subjective symptoms. Methods and Results: An observational study was conducted with 13 women who had unilateral, upper extremity BCRL. Fluid distribution was evaluated by using two magnetic resonance imaging (MRI) sequences: half-Fourier acquisition single-shot turbo spin echo and three-dimensional double-echo steady-state. The presence of swelling was determined by lymphedema therapists, and subjective symptoms were measured by using a visual analog scale. On MRI, no participants had any free water signals in the trunk. However, seven had swelling and all 13 had some kind of subjective symptoms on the affected side of their trunk. Conclusions: These results suggest that swelling and subjective symptoms do not correlate with the presence of truncal fluid. For such cases, a different approach than MLD may be needed to address truncal swelling and related subjective symptoms. Checking for the presence of fluid in the truncal region may help MLD be used more appropriately.

DOI： 10.1089/lrb.2020.0075

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Ceramic Society  

Cobalt manganite-based hierarchically porous monoliths (HPMs) with three-dimensionally (3D) interconnected macropores and open nanopores have been prepared via the sol–gel process accompanied by phase separation. The controlled hydrolysis and polycondensation of the brominated metal alkoxides, which are generated from an incomplete reaction between epichlorohydrin and MBr2 (M = Co and Mn) in N,N-dimethylformamide (DMF), form a monolithic gel based on the two divalent metal cations. The dual-polymer strategy using polyvinylpyrrolidone (PVP) and poly(ethylene oxide) (PEO) effectively induces the spinodal decomposition, where PVP and PEO are preferentially distributed to the gel phase and fluid phase, respectively, resulting in a porous gel characterized by the co-continuous structure. The effects of DMF and PVP on the porous morphology derived from the phase separation have been systematically studied. Calcination of the as-dried gels allows for the crystallization into the spinel phase yielding hierarchically porous CoMn2O4 monoliths, which have been examined in detail by the structural and compositional analyses.

DOI： 10.1111/jace.17662

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Advances  

We report a new synthetic strategy for melamine-formaldehyde (MF) monoliths with controlled hierarchical porosity toward metal-ion scavengers. The obtained MF monoliths possessed micro-, meso- and macroporosity, which allowed efficient adsorption performance of precious metal ions in water. Applications such as recovery/removal of metal ions are expected.

DOI： 10.1039/d1ma00034a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry C  

Porous architecture is key in the nonaqueous lithium-oxygen (Li-O2) electrode process, which is attracting huge interest because of its application in reversible energy storage with high theoretical energy density. However, it is still challenging to understand the optimal porous structure to obtain high reversibility of the reaction. One main reason is because of instability and undefined porous structures of standard electrodes consisting of carbonaceous materials, and this issue hinders from unveiling the fundamental mechanism in the complicated electrode process. Here, we developed a new synthetic strategy to design monolithic electrodes of pure metallic nickel with controlled bimodal porous structures. The present work aims to investigate the fundamental effects of the bimodal macroporous structure in the Li-O2 electrode process under carbon-/binder-free stable model electrodes. As the result, we found that, depending on the multiscale structural configurations, the bimodal macroporous structure gave significant influences to key properties, such as the efficiency of redox-mediators, discharge overpotential, and cycling life. This work indicates that the rational design of stable and conductive porous materials is one of the promising approaches to investigate highly complicated electrochemical reactions in porous electrodes and suggest new guidelines for further development of hierarchically structured electrodes toward advanced electrochemical systems.

DOI： 10.1021/acs.jpcc.0c10446

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：National Science Review  

Hierarchically porous monoliths based on copper (Cu), cobalt (Co) and manganese (Mn) oxides with three-dimensionally (3D) interconnected macropores and open nanopores were prepared using metal bromides as precursors via a sol-gel process accompanied by phase separation. The difficulty of gelation for low-valence metal cation was overcome by introducing a highly electronegative Br atom near to the metal atom to control the rates of hydrolysis and polycondensation. The 3D interconnected macropores were obtained using appropriate polymers to induce phase separation. The domain sizes of macropores and skeletons can be controlled by reaction parameters such as concentration and/or average molecular weight of polymers, and the amount of hydrochloric acid. The crystalline metal oxide monoliths with their 3D interconnected macroporous structure preserved were obtained after heat treatment in air.

DOI： 10.1093/nsr/nwaa103

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Hierarchically porous materials with large pores in the micrometer range and small pores in the nanometer range, where the large pores facilitate mass transport and the small pores supply numerous active sites, show superiority to materials with unimodal pores in the fields of separation and adsorption. Among all the methods used to prepare hierarchically porous monoliths (HPMs), the sol–gel process accompanied by spinodal decomposition (or phase separation) shows its advantages such as facile method, no template, precise structural control, good reproducibility, and availability for various kinds of materials. This review focuses on the specific process to prepare various types of HPMs including silica, metal oxides, metal phosphates, and metal–organic hybrids, via the sol–gel process accompanied by spinodal decomposition. The HPMs composed of organic polymer and their carbonized derivatives prepared by polymerization-induced phase separation are also covered in this review as an example of similar morphological formation in purely organic crosslinking reactions. This review directs the most attention to the preparation of monolithic gels (sol–gel process) and the control of macroporous structure (phase separation). [Figure not available: see fulltext.].

DOI： 10.1007/s10971-020-05370-4

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

A superhydrophobic mesoporous silica material loaded with on-site formed small Ag nanoparticles has been prepared via surface modification with octadecylsilane (C18H37SiH3) and subsequent reduction of silver acetate with residual hydrido groups on-site. The resultant material shows excellent antibacterial activity for Gram-negative E. coli and Gram-positive S. aureus. This journal is

DOI： 10.1039/d0nj02502j

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry B  

We report novel superhydrophobic highly flexible composites based on a doubly cross-linked (DCL) aerogel and carbon nanotubes (CNTs) for strain/pressure sensing. The DCL aerogel/CNT composite is prepared by radical polymerization of vinylmethyldimethoxysilane and vinyldimethylmethoxysilane, respectively, followed by hydrolytic co-polycondensation of the obtained polyvinylmethyldimethoxysilane and polyvinyldimethylmethoxysilane, combined with the incorporation of CNTs. Benefiting from the flexible methyl-rich DCL structure of the aerogel and conductive CNTs, the resultant DCL aerogel/CNT composite combines superhydrophobicity, high compressibility, high bendability, high elasticity, and strain- and pressure-sensitive conductivity. We demonstrate that the composite can be applied as a high-performance strain/pressure sensor for the detection of arterial pulse waves and joint bending with high sensitivity and high durability against humidity.

DOI： 10.1039/c9tb02953b

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

We report new polyorganosiloxane aerogels with superhydrophobicity, high elasticity, and high bendability based on polyvinyl-poly(dimethylsiloxane) (PVPDMS)/polymethylsilsesquioxane (PMSQ). They are synthesized by a radical polymerization/co-polycondensation strategy that involves radical polymerization of vinyldimethylmethoxysilane to obtain chainlike polyvinyldimethylmethoxysilane (PVDMMS) polymers followed by hydrolytic co-polycondensation of PVDMMS polymers and methyltrimethoxysilane combined with ambient pressure drying without any post-gelation modifications. The resultant PVPDMS/PMSQ aerogels exhibit a highly tunable triple-network structure consisting of flexible inter-cross-linked hydrocarbon polymers, poly(dimethylsiloxane), and PMSQ. The aerogels with a low content of PVPDMS exhibit small pore sizes (2-80 nm), good transparency, high surface areas, and thermal superinsulation (λ = 0.0148 W m-1 K-1), while those with a high content of PVPDMS exhibit large pore sizes (100 nm-3 μm) and excellent selective absorption for organic liquids. In addition, incorporation of graphene oxide (GO) in PVPDMS/PMSQ aerogels can afford highly flexible PVPDMS/PMSQ/GO composite aerogels, which show efficient separation of three-component water/oil/dye mixtures. These aerogels are promising in the practical applications of thermal insulation, absorption/adsorption, and separation.

DOI： 10.1021/acs.chemmater.9b04877

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Nano Materials  

Aerogels have many unique properties such as low density and low thermal conductivity, and, in particular, transparent silica aerogels are attractive for thermal insulating windows. Practical applications of silica aerogels, however, have been limited because of their low mechanical strength, and it is still challenging to synthesize transparent and mechanically strong aerogels. Here, we report colorless transparent melamine-formaldehyde (MF) aerogels prepared via a nonaqueous synthetic strategy. The obtained transparent MF aerogel with a density of 0.18 g cm-3 shows significantly higher mechanical strength and a lower thermal conductivity of ca. 13 mW m-1 K-1 compared to conventional silica aerogels with similar density.

DOI： 10.1021/acsanm.9b02275

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Angewandte Chemie - International Edition  

We present a two-step template-free approach toward monolithic materials with controlled trimodal porous structures with macro-, meso-, and micropores. Our method relies on two ordering processes in discrete length scales: 1) Spontaneous formation of macroporous structures in monolithic materials by the sol–gel process through the short-range ordered self-assembly of metal–organic frameworks (MOFs), and 2) reorganization of the framework structures in a mediator solution. The Zr-terephthalate-based MOF (UiO-66-NH2) was adopted as a proof of concept. The self-assembly-induced phase separation process offered interconnected macropores with diameters ranging from 0.9 to 1.8 μm. The subsequent reorganization process converted the microporous structure from low crystalline framework to crystalline UiO-66. The resultant mesopore size within the skeletons was controlled in the range from 9 to 21 nm. This approach provides a novel way of designing spaces from nano- to micrometer scale in network-forming materials.

DOI： 10.1002/anie.201911499

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials and Design  

Resilient, fire-retardant and mechanically strong polyimide-polyvinylpolymethylsiloxane (PI-PVPMS) composite aerogels have been prepared via stepwise chemical liquid deposition (SCLD). The synthesis is based on the formation of PI-PVPMS crosslinked network structure with (3-aminopropyl)trimethoxysilane (APTMS) as a coupling agent to provide reactive sites on the backbone. We successfully realize the PI in-situ growth on the whole super-flexible PVPMS gel skeleton with this simple method. The effect of APTMS amount and deposition time on the properties of final samples is deeply investigated. The resultant PI-PVPMS composite aerogels show excellent mechanical and thermal properties. They can support at least 10,000 times of their own weight and can recover 20% from a 60% of compressive strain, with an elastic modulus of 32 MPa. For thermal performance, they can maintain their structural integrity after being subjected to the alcohol lamp outer flame of around 650 °C for 30 min. These results together with the simple synthesis process demonstrate the potential for construction materials using PI-PVPMS composite aerogels. Furthermore, the SCLD synthesis method could also be applied to prepare other composite aerogels, especially for those containing complex polymer.

DOI： 10.1016/j.matdes.2019.108096

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Aerogels have attracted great interest for their unique properties, but their mechanical brittleness and poor functionality highly limit their practical applications. Herein, we report unprecedented superelastic multifunctional aminosilane-crosslinked reduced graphene oxide (AC-rGO) aerogels that are prepared via a facile and scalable strategy involving simultaneous crosslinking and reducing of graphene oxide nanosheets with different kinds of aminosilanes via C-N coupling and hydrolytic polycondensation reactions. It is found that 3-aminopropyl(diethoxy)methylsilane (APDEMS) is the better choice to enhance hydrophobicity, elasticity, and other properties of the resulting aerogels compared with (3-aminopropyl)triethoxysilane. One APDEMS molecule plays three roles as a crosslinker, a reductant, and a hydrophobizing agent. An outstanding combination of high surface area, ultralow density, superhydrophobicity, supercompressibility, superelasticity, low thermal conductivity, ultrahigh absorption capacity for organic liquids, efficient three-component separation, and strain/pressure sensing has been achieved in a single APDEMS-crosslinked rGO aerogel for the first time. In addition, a flexible, highly sensitive, and moisture-resistant AC-rGO aerogel-based strain/pressure-sensing array for the effective detection of strain (0-80%)/pressure (10 Pa to 10 kPa) distributions and object shapes has been demonstrated.

DOI： 10.1021/acsami.9b16746

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer Chemistry  

Aerogels exhibit unique properties, but their practical applications have been restricted by low mechanical strength and costly supercritical drying; it remains difficult to obtain highly flexible aerogels with good thermal insulation and absorption by ambient pressure drying (APD). Here, we report novel highly flexible aerogels based on the polyvinylpolymethylsiloxane (PVPMS)/polyvinyltrimethylsilane (PVTMS) co-network, which consists of inter-cross-linked hydrocarbon and siloxane polymers with dangling trimethylsilyl groups, and its nanocomposite with polypyrrole (PPy). The PVPMS/PVTMS copolymer aerogels are facilely synthesized by a consecutive radical co-polymerization and hydrolytic polycondensation strategy from two monomers vinylmethyldimethoxysilane and trimethylvinylsilane without additional cross-linkers, followed by APD without any post-gelation modification. The PPy nanocomposite aerogels are synthesized by an in situ oxidation polymerization of pyrrole in the copolymer aerogel networks, followed by APD. The resulting aerogels consist of meso-to macro-scaled pore structures with tunable skeleton and pore sizes with variable cross-linking density and bulk density. In addition, these aerogels show good hydrophobicity and high flexibility in both compression and bending. Moreover, different functionalities such as excellent thermal insulation, oil-water separation, and pressure sensing can be imparted, allowing them to exhibit potential applications in thermal insulation, separation, and sensing.

DOI： 10.1039/c9py00751b

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Recently, many efforts have been made to develop various smart sensors. However, achieving flexible multifunctional sensors combining excellent sensing of temperature, strain, and pressure with a single material is still challenging. Here, we report unprecedented superhydrophobic ultraflexible reduced graphene oxide (rGO)/polyorganosiloxane aerogels and high-performance multifunctional temperature/strain/pressure sensors based on these aerogels. GO nanosheets are first cross-linked and reduced with (3-aminopropyl)triethoxysilane (APTES) to obtain APTES-modified rGO aerogels, which are then further covalently cross-linked with polyvinylmethyldimethoxysilane polymers and vinylmethyldimethoxysilane via copolycondensation to afford rGO/polyorganosiloxane aerogels. The resulting aerogels exhibit a coralline-like triple-network nanostructure consisting of rGO nanosheets, polyvinyl-poly(methylsiloxane), and poly(vinylmethylsiloxane) that are cross-linked with each other. The aerogels combine superhydrophobicity, high compressibility, high bendability, superelasticity, excellent machinability, and temperature-, strain-, and pressure-sensitive conductivity, which is a combination not observed with traditional materials. In addition, an rGO/polyorganosiloxane aerogel-based flexible multifunctional sensing array combining sensing of temperature (20-100 °C), strain (in the wide range of 0.1-80%), and pressure (in the wide range of 10 Pa to 110 kPa) with high sensitivity and high durability against compression, bending, and humidity has been demonstrated for the first time.

DOI： 10.1021/acs.chemmater.9b02437

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

A facile method for the preparation of zinc oxide with three-dimensionally (3D) interconnected macropores has been developed. The Zn-based monolithic gel was obtained using citric acid (CA) as a structure supporter via an epoxide-mediated sol-gel method accompanied by phase separation. The size of the macropores could be controlled by the ratio of methanol to propylene oxide in the starting solution. The Zn-based gel was heat-treated in air with the purpose of removing the organic components and crystallizing the ZnO, finally resulting in pure ZnO (purity >90%, with negligible carbon content) with 3D interconnected macropores and an open nanoscale network. The influence of the starting solvent composition on the Zn-based gel morphologies has been examined and discussed based on the chemical compatibility of the Zn-CA complex with other components.

DOI： 10.1039/c9nj02373a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Sustainable Chemistry and Engineering  

The catalytic performance of hierarchically porous niobium phosphate (NbP) supported magnesia for the glucose isomerization to fructose, was investigated under atmospheric air atmosphere. Porous NbP showed improved support effects on MgO in comparison to other metal oxides tested for glucose isomerization. Also, the amount and distribution of basic sites were largely changed by supporting magnesia on NbP. Although the textural properties were reduced and solid acids formed on the MgO/NbP catalysts, glucose isomerization was promoted by increasing magnesium content. The maximum yield of fructose reached ∼24.6% over 40%MgO/NbP-500 with selectivity of 65.7% for 1.0 wt % glucose at 120 °C. The fructose productivity peaked as high as 13.6 g g catalyst-1 h -1 over 40%MgO/NbP-700 catalyst. The leaching of cations and anions resulted in a homogeneous system for glucose isomerization. Regeneration almost fully reactivated the catalyst to its initial activity. The MgO/NbP showed high stability under air atmosphere for 15 days, and high potential use for glucose isomerization.

DOI： 10.1021/acssuschemeng.9b00292

Web of Science

Scopus

researchmap

担当区分：責任著者   記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Abstract: Utilizing the spontaneous wetting of oligomeric silica-phase via phase-separation onto a solid surface in a confined dimension, sub-micrometer thick mesoporous layers have been coated on the surface of nonporous skeletons of preformed macroporous silica gels. The size and volume of mesopores within the layers could be controlled by subsequent aging conditions similarly to those reported for fully porous monolithic silica. Comparison of HPLC efficiencies of these novel type monolithic gels, core-shell silica monoliths, with those of a conventional silica monolith revealed that the retention factor per unit surface area became larger for core-shell silica monoliths. The increase in dynamic accessibility of analyte molecules to the mesopores well explain the improved retention factors in core-shell silica monoliths. [Figure not available: see fulltext.]

DOI： 10.1007/s10971-018-4889-2

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Abstract: Here, we overview the developments in the past decade made on organic–inorganic hybrid aerogels and xerogels based on silicone (polyorganosiloxanes) through persistent works by the authors to increase the mechanical strength and flexibility and add functionality. Polymethylsilsesquioxane (PMSQ, CH3SiO3/2) has been found to show unusual strength and flexibility against compression, and their bending properties can also be improved by several strategies. Silicone-based networks with organic bridges between inorganic moieties are also beneficial for these improvements. In particular, organic bridges with a higher fraction and more extended length have been found to allow higher durability against large deformations. In addition, functional groups such as vinyl, chloromethyl, and amino can readily be introduced by starting from organoalkoxysilanes with these functional substituents (e.g., FG−Si(OR)3 or (RO)3Si−FG−Si(OR)3, where FG shows an organic substituent containing functional groups and R is typically methyl or ethyl), and other functional groups such as carboxyl can be introduced by post-gelation modifications on the pre-installed FG in the network. Possibilities in applications such as thermal insulators, photoluminescent media, and photocatalysts are also discussed. [Figure not available: see fulltext.].

DOI： 10.1007/s10971-018-4804-x

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Hierarchically porous magnesium oxide, MgO, monoliths with a well-defined continuous macroporous structure have been synthesized via the sol–gel route accompanied by phase separation. Magnesium chloride hexahydrate was used as a precursor, and propylene oxide was used as an acid scavenger to raise the pH of a reaction solution homogenously. In order to obtain a crack-free monolith after heating in air, poly(vinylpyrrolidone), PVP, was employed as a scaffold of the skeleton as well as a phase separation controller to form the continuous macropores with higher homogeneity. Due to the moderate hydrogen-bonding interaction with magnesium hydroxide, PVP reinforces the gel network essentially composed of fine grained magnesium hydroxide. Even after the removal of all organic components by calcination, the porous gel samples maintained their monolithic form. On the other hand, an additional incorporation of 1,3,5-benzenetricarboxylic acid, H3BTC, was found to be effective in suppressing the oriented growth of the micrometer-sized crystalline phase. The polycrystalline MgO monoliths with specific surface area of 185, 64, and 48 m2 g−1 were prepared after heating at 400, 500, and 600 °C in air, respectively. [Figure not available: see fulltext.].

DOI： 10.1007/s10971-018-4682-2

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1038/s41598-018-34220-1

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Abstract: Hierarchically porous spinel-type binary metal oxide MgAl2O4 with cocontinuous skeletons and interconnected macropores has been synthesized by a facile sol–gel method accompanied by phase separation, in which poly (ethylene oxide) (PEO) works as phase separation inducer to form micrometer-scale phase-separated macrochannels at the same time of sol–gel transition. The obtained xerogels exhibit in the form of a monolith with well-defined macropores and cocontinuous dense skeletons by adjusting the amount of PEO. The xerogel and those heat-treated at or below 600 °C are amorphous, and heat-treatment at or above 700 °C allows the precipitation of complete crystalline MgAl2O4 spinel with a macropore size of 0.7–0.9 μm, a porosity of 60–70%, and a BET surface area of 40–80 m2 g−1, without spoiling the macrostructure of monoliths. Three anionic dyes and two cationic dyes are selected as targeted adsorbates to investigate the selective adsorption ability of a hierarchically porous MgAl2O4 spinel. The resultant MgAl2O4 spinel shows a high affinity and adsorption rate toward anionic dyes Congo Red, Methyl Orange, and Methyl Blue. The maximum adsorption capacity of MgAl2O4 spinel toward these three anionic dyes are 2721.6 mg g−1 for Congo Red, 2469.7 mg g−1 for Methyl Orange, and 6771.9 mg g−1 for Methyl Blue, respectively. [Figure not available: see fulltext.]

DOI： 10.1007/s10971-018-4781-0

Web of Science

Scopus

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Nature  

Galaxies in the early Universe that are bright at submillimetre wavelengths (submillimetre-bright galaxies) are forming stars at a rate roughly 1,000 times higher than the Milky Way. A large fraction of the new stars form in the central kiloparsec of the galaxy1–3, a region that is comparable in size to the massive, quiescent galaxies found at the peak of cosmic star-formation history4 and the cores of present-day giant elliptical galaxies. The physical and kinematic properties inside these compact starburst cores are poorly understood because probing them at relevant spatial scales requires extremely high angular resolution. Here we report observations with a linear resolution of 550 parsecs of gas and dust in an unlensed, submillimetre-bright galaxy at a redshift of z = 4.3, when the Universe was less than two billion years old. We resolve the spatial and kinematic structure of the molecular gas inside the heavily dust-obscured core and show that the underlying gas disk is clumpy and rotationally supported (that is, its rotation velocity is larger than the velocity dispersion). Our analysis of the molecular gas mass per unit area suggests that the starburst disk is gravitationally unstable, which implies that the self-gravity of the gas is stronger than the differential rotation of the disk and the internal pressure due to stellar-radiation feedback. As a result of the gravitational instability in the disk, the molecular gas would be consumed by star formation on a timescale of 100 million years, which is comparable to gas depletion times in merging starburst galaxies5.

DOI： 10.1038/s41586-018-0443-1

Scopus

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

Web of Science

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Catalysis Science and Technology  

Hierarchically porous niobium phosphate (NbP) was synthesised via a sol-gel method accompanied by phase separation and employed as a catalyst for fructose dehydration. The niobium precursor was prepared by digesting ammonium niobate(v) oxalate in aqueous H2O2 with citric acid as a chelating agent to prevent the precipitation of niobium hydroxide. Poly(acrylamide) and poly(ethylene glycol) were used as phase separation inducers to produce co-continuous macropores and gel skeletons. The NbP sample calcined at 600 °C for 8 h had a high surface area (SBET ∼140 m2 g-1) and large acidity (0.84 mmol-NH3 g-1). The NbP monolith was amorphous after calcination at 600 °C and transformed into an α-NbOPO4 phase at 1000 °C. The NbP monolith calcined at 600 °C was an efficient acid catalyst for the dehydration of fructose to 5-hydroxymethylfurfural in water (70% yield) or in aqueous dimethyl sulfoxide (90% yield). The productivity of HMF reached 7.3 × 10-2 mol h-1 per kg-solution at an initial fructose concentration of 10.0 wt% in water with a catalyst loading of 2.0 wt%.

DOI： 10.1039/c8cy00803e

Web of Science

Scopus

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inorganic Chemistry Frontiers  

Simple post-treatments of the porous titania monolith in varied concentrations of phosphoric acid solution provide a series of monolithic titanium phosphates (TiPs) with a hierarchically porous structure together with an exquisite macropore surface. Depending on the reaction conditions, platy crystallites composed of either Ti2O3(H2PO4)2·2H2O, Ti(HPO4)2·H2O (α-TiP), or Ti2O(PO4)2·2H2O (π-TiP) are generated on the macropore skeleton via a dissolution and reprecipitation process, which forms distinct wrinkled surface morphologies. In addition, the treatments effectively suppress the shrinkage during drying, leading to lower bulk density. Post-calcination in air yields porous titanium pyrophosphates preserving the intricate porous architecture in some cases. Notably, the hierarchically porous TiP2O7 monoliths prepared from the α-TiP precursors have a good thermal robustness related to bulk density.

DOI： 10.1039/c8qi00146d

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

Iron(iii) oxyhydroxide and oxide monoliths with controlled multiscale porosity have been successfully fabricated via the sol-gel process accompanied by phase separation. The size of macropores was controlled by synthesis parameters such as starting compositions. The as-dried iron(iii) oxyhydroxide monoliths were amorphous and possessed surface areas over 340 m2 g-1, of which mesostructures could be further controlled by a heat-treatment at 250-350 °C without collapse of macrostructures and monolithic forms. When the as-dried gel was heated at 300 °C, the resultant gel transformed to crystalline α-Fe2O3 and exhibited a specific surface area of 124 m2 g-1. Heat-treatment at 350 °C resulted in the broadened size distribution of mesopores. The adsorption behavior of Congo red has revealed that the interconnected macroporous structure contributed to faster diffusion and better accessibility in a continuous flow-through set up, and the crack-free monolithic forms accounted for an advantageous use of the flow-through adsorbents.

DOI： 10.1039/c8ta01691g

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

A facile yet versatile approach to transparent, highly flexible, machinable, superinsulating organic-inorganic hybrid aerogels is presented. This method involves radical polymerization of a single alkenylalkoxysilane to obtain polyalkenylalkoxysilane, and subsequent hydrolytic polycondensation to afford a homogeneous, doubly cross-linked nanostructure consisting of polysiloxanes and hydrocarbon polymer units. Here we demonstrate that novel aerogels based on polyvinylpolysilsesquioxane (PVPSQ), polyallylpolysilsesquioxane (PAPSQ), polyvinylpolymethylsiloxane (PVPMS), and polyallylpolymethylsiloxane (PAPMS) are facilely prepared via this approach from vinyltrimethoxysilane (VTMS; or vinyltriethoxysilane, VTES), allyltrimethoxysilane (ATMS; or allyltriethoxysilane, ATES), vinylmethyldimethoxysilane (VMDMS), and allylmethyldimethoxysilane (AMDMS), respectively. These aerogels combine low density, uniform nanopores, high transparency, supercompressibility, high bendability, excellent machinability, and thermal superinsulation (λ = 14.5-16.4 mW m-1 K-1). More importantly, transparent, superflexible, superinsulating aerogels are obtained with PVPMS and PAPMS via highly scalable ambient pressure drying without any solvent-exchange and modifications for the first time. This work will open a new way to transparent, highly flexible porous materials, promising in the practical applications of thermal superinsulators, adsorbents, sensors, etc.

DOI： 10.1021/acs.chemmater.8b00563

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Nano  

Aerogels have many attractive properties but are usually costly and mechanically brittle, which always limit their practical applications. While many efforts have been made to reinforce the aerogels, most of the reinforcement efforts sacrifice the transparency or superinsulating properties. Here we report superflexible polyvinylpolymethylsiloxane, (CH2CH(Si(CH3)O2/2))n, aerogels that are facilely prepared from a single precursor vinylmethyldimethoxysilane or vinylmethyldiethoxysilane without organic cross-linkers. The method is based on consecutive processes involving radical polymerization and hydrolytic polycondensation, followed by ultralow-cost, highly scalable, ambient-pressure drying directly from alcohol as a drying medium without any modification or additional solvent exchange. The resulting aerogels and xerogels show a homogeneous, tunable, highly porous, doubly cross-linked nanostructure with the elastic polymethylsiloxane network cross-linked with flexible hydrocarbon chains. An outstanding combination of ultralow cost, high scalability, uniform pore size, high surface area, high transparency, high hydrophobicity, excellent machinability, superflexibility in compression, superflexibility in bending, and superinsulating properties has been achieved in a single aerogel or xerogel. This study represents a significant progress of porous materials and makes the practical applications of transparent flexible aerogel-based superinsulators realistic.

DOI： 10.1021/acsnano.7b07117

Web of Science

Scopus

PubMed

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Bunseki Kagaku  

A macroporous resorcinol-formaldehyde (RF) xerogel was synthesized via sol–gel reaction, accompanied by phase separation; a graphitized carbon monolith was then prepared by calcining the RF xerogel at a relatively low temperature (1200 °C) utilizing catalytic graphitization. The retention behaviors of metal-EDTA complexes on the carbon monolithic column were investigated. The carbon monolith exhibited catalytic activity for redox reactions, like porous graphitic carbon packing materials do; they oxidized Co(II)-EDTA to Co(III)-EDTA during elution. Their redox activity could be modified by treating with an eluent containing an oxidizing or reducing agent. A novel on-line redox derivatization HPLC system using a carbon monolithic column was developed for enhancing the separation selectivity. This on-line redox derivatization HPLC system consisted of two ODS columns as a separation column and one carbon monolithic column as redox derivatization unit placed between them. The Co(II)-EDTA migrated as its original oxidation state in the first ODS column, while it migrated as Co(III)-EDTA in the second ODS column, since Co(II)-EDTA was rapidly oxidized to Co(III)-EDTA in the carbon monolithic column. On the other hand, other metal-EDTA complexes migrated as their original oxidation states in these columns. Therefore, the Co-EDTA could be separated from the other metal-EDTA complexes. This on-line redox derivatization HPLC system was successfully used for determining the trace amount of cobalt in a reference copper alloy.

DOI： 10.2116/bunsekikagaku.67.469

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.2147/JPR.S156326

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Alloys and Compounds  

Hierarchically porous ZnAl2O4 spinel monolith derived from ionic precursors has been successfully prepared via the sol-gel route accompanied by phase separation in the presence of poly (ethylene oxide) (PEO) and propylene oxide (PO). Appropriate amounts of PEO as a phase-separation inducer and PO as a gelation mediator allow the formation of the xerogel with bicontinuous macrostructure and a monolithic shape. The macropore size of the resultant dried gel is mainly distributed in the range of 0.2–1 μm, and the whole porosity is about 65%. The dried gel is constructed by crystalline Zn–Al hydrotalcite, becoming amorphous after heat-treated at 300–500 °C in air, and is further transformed into single phase ZnAl2O4 spinel with plate-like shape at 600 °C. The macroporous structure is well maintained while the porosity increases to 75% and the surface area rises to 109 m2 g−1 after heat-treatment.

DOI： 10.1016/j.jallcom.2017.08.172

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Langmuir  

Reactions of chloromethyltrimethoxysilane (CMTMS) and its derived colloidal network polychloromethylsilsesquioxane (PCMSQ) have been investigated to extend the material design strategy toward functionalized and mechanically reinforced aerogels. In a carefully designed sol-gel system, CMTMS has afforded transparent aerogels in the presence of cationic surfactant. The surface chloromethyl groups with polarity and reactivity are shown to be useful for supporting nanostructures, with photoluminescent carbon dots (C-dots) prepared from polyethylenimine and citric acid as an example. Furthermore, since nucleophilic substitution (SN2) reactions on the surface chloromethyl groups are found to control the equilibrium of formation/dissociation of siloxane bonds, a new gelation strategy triggered by SN2 reactions in sol-gel has been developed. In the presence of nucleophilic organic species such as polyamines, a hybrid network consisting of PCMSQ cross-linked with a polyamine nucleophile can be prepared to enhance mechanical properties of aerogel.

DOI： 10.1021/acs.langmuir.7b03013

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer Journal  

We report the shapeable synthesis of porous silica frameworks using polyacrylamide (PAAm) gel as an organic template and hydrolyzed silicon alkoxide as a silica source. Macroscopically shaped porous frameworks - such as plates, tablets and sheets - comprised of 20- to 40-nm diameter silica particles are obtained via PAAm-silica precursor gels. The mechanical properties (i.e., hardness and Young's modulus) of the silica frameworks depend on the packing density and are controlled by changing the silica content in PAAm gels.

DOI： 10.1038/pj.2017.62

Web of Science

Scopus

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Astrophysical Journal Letters  

We report the study of the far-infrared (IR) sizes of submillimeter galaxies (SMGs) in relation to their dustobscured star formation rate (SFR) and active galactic nuclei (AGN) presence, determined using mid-IR photometry. We determined the millimeter-wave (λobs = 1100 μm) sizes of 69 Atacama Large Millimeter/ submillimeter Array (ALMA)-identified SMGs, selected with ≥10 δ confidence on ALMA images (F1100 μm = 1.7-7.4 mJy). We found that all of the SMGs are located above an avoidance region in the sizeflux plane, as expected by the Eddington limit for star formation. In order to understand what drives the different millimeter-wave sizes in SMGs, we investigated the relation between millimeter-wave size and AGN fraction for 25 of our SMGs at z=1-3. We found that the SMGs for which the mid-IR emission is dominated by star formation or AGN have extended millimeter-sizes, with respective median Rc,e = 1.6-0.21+0.34 and 1.5 -0.24+0.93 kpc. Instead, the SMGs for which the mid-IR emission corresponds to star-forming/AGN composites have more compact millimeter-wave sizes, with median Rc,e1.0 -0.20+0.20kpc. The relation between millimeter-wave size and AGN fraction suggests that this size may be related to the evolutionary stage of the SMG. The very compact sizes for composite star-forming/AGN systems could be explained by supermassive black holes growing rapidly during the SMG coalescing, star-formation phase.

DOI： 10.3847/2041-8213/aa9572

Scopus

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Omega  

Room-temperature stable macroporous mayenite electride (C12A7:e-) has been successfully prepared via a sol-gel method accompanied by phase separation, followed by heat-treatment and reduction processes. The obtained xerogel monoliths possess controllable macrostructure and a porosity of more than 60%, depending on adjusting the amount of poly(ethylene oxide) as a phase separation inducer. Heat-treatment allows the formation of multicrystals Ca12Al14O32Cl2 and Ca12Al14O33 (C12A7), and the porosity increases to 78.67% after being heat-treated at 1100 °C. Further reduction promotes the transformation from Ca12Al14O32Cl2 or C12A7 to C12A7:e- as well as the conversion from an insulator to a semiconductive electride. The carrier concentration of the electride reaches 3.029 × 1018 cm-3 after being reduced at 1100 °C under Ar atmosphere, and the porosity still remains 66%. The macrostructure of the resultant mayenite electride before and after heat-treatment and reduction is perfectly preserved, indicating that the obtained macroporous monolithic mayenite electride could be utilized in the electronic components.

DOI： 10.1021/acsomega.7b01121

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：CrystEngComm  

In this report, we demonstrate a facile and versatile methodology for synthesizing a series of titanium phosphates (TiPs) with various morphologies. The hydrothermal reactions of TiO2 in different concentrations of H3PO4 aq. yield 4 types of crystal structures with diverse shapes, such as nanoparticles, nanorods and nanosheets, which are assembled into a variety of flower-like morphologies. The dependence of the crystal phases and morphologies of TiPs on the synthesis conditions have been comprehensively investigated. This synthetic process can be further extended to other TiP derivatives incorporated with guest cations (e.g. NH4+ and Na+) simply by adding the corresponding phosphate salts to the starting composition, which leads to the morphological variation associated with the change of the crystal phase. The mechanism for the formation of the TiPs is discussed in terms of the stable Ti-based ion species relying on the pH value of the reaction solution. In addition, the correlation between the crystal structures and morphologies of TiPs and their electrochemical Li- and Na-ion storage behaviors are demonstrated as well, which discloses the different tendencies of morphological effects between the Li- and Na-ion systems.

DOI： 10.1039/c7ce01123g

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.chemmater.7b02431

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Asian Ceramic Societies  

Phase separation control is an important factor to prepare a porous monolith by an aqueous sol–gel reaction. Here, we report a surfactant-free synthesis method to obtain hydrophobic polymethylsilsesquioxane aerogels by copolymerizing a cationic-functionalized alkoxysilane N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride. The resultant materials have low-density, high visible-light transmittance, and high thermal insulating equivalent to those of prepared under the presence of surfactant.

DOI： 10.1016/j.jascer.2017.02.003

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

A novel CO2 sorbent was prepared by modifying polyethyleneimine (PEI) on hierarchically porous silica (HPS) monoliths with well-defined macro-mesopores through wet impregnation method. HPS monoliths before and after functionalization were characterized by scanning electron microscopy (SEM), differential thermal analysis/thermogravimetry (DTA/TG), fourier transform infrared spectroscopy (FT-IR) and nitrogen adsorption/desorption analysis (BET), and the CO2 adsorption-regeneration properties of as-synthesized sorbents were investigated by thermogravimetric analysis (TG). The effects of loaded PEI amount as well as adsorption temperature and CO2 partial pressure on the CO2 adsorption performance of the as-prepared sorbents were also studied. The results showed that the porous structure of HPS-PEI sorbents was preserved after functionalization, while the specific surface area and pore volume decreased with increasing amount of amines to some extent. The use of PEI had a remarkable improvement on the CO2 adsorption capacity. With the increasing amount of PEI loaded, the CO2 adsorption capacity improved significantly. The highest CO2 adsorption capacity of 2.44 mmol (g sorbent)−1 was obtained at 75 °C in the CO2 partial pressure of 100 kPa for the HPS loaded with 60 wt% PEI. Adsorption/desorption cycles indicated that the PEI-modified HPS sorbents had a good stability and regeneration.

DOI： 10.1016/j.micromeso.2017.02.076

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Langmuir  

Transparent, low-density ethenylene-bridged polymethylsiloxane [Ethe-BPMS, O2/2(CH3)Si-CHCH-Si(CH3)O2/2] aerogels from 1,2-bis(methyldiethoxysilyl)ethene have successfully been synthesized via a sol-gel process. A two-step sol-gel process composed of hydrolysis under acidic conditions and polycondensation under basic conditions in a liquid surfactant produces a homogeneous pore structure based on cross-linked nanosized colloidal particles. Visible-light transmittance of the aerogels varies with the concentration of the base catalyst and reaches as high as 87% (at a wavelength of 550 nm for a 10 mm thick sample). Gelation and aging temperature strongly affect the deformation behavior of the resultant aerogels against uniaxial compression, and the obtained aerogels prepared at 80 °C show high elasticity after being unloaded. This highly resilient behavior is primarily derived from the rigidity of ethenylene groups, which is confirmed by a comparison with other aerogels with similar molecular structures, ethylene-bridged polymethylsiloxane and polymethylsilsesquioxane. Applicability of the addition reaction using a Diels-Alder reaction of benzocyclobutene has also been investigated, revealing that a successful addition takes place on the ethenylene linkings, which is verified using Raman and solid-state NMR spectroscopies. Insights into the effect of molecular structure on mechanical properties and the availability of surface functionalization provided in this study are important for realizing transparent aerogels with the desired functionality.

DOI： 10.1021/acs.langmuir.7b00434

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry - A European Journal  

Aerogels are attracting increasing attention due to their high thermal insulation ability as well as unique properties such as high porosity, surface area, and transparency. However, low mechanical strengths, originating from their unique porous structure, impede handling, formability, mass production, and extended applications. This minireview focuses on the strengthening of aerogels by several organic–inorganic hybridization strategies. In particular, successful strengthening methodologies, which employ organo-substituted alkoxysilanes as the single precursor for the sol–gel preparations, developed by the authors are highlighted. Moreover, improvements in compressive strength and elasticity lead to monolithic aerogel-like xerogels through ambient pressure drying. Correlations between structures in different length scales (e.g., molecular, network, and pore structure levels) and resultant mechanical properties are discussed for further understandings and better design toward mechanically improved aerogels/xerogels and their applications.

DOI： 10.1002/chem.201603680

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Abstract: Systematic investigations on the effect of synthetic conditions onto the properties of polyvinylsilsesquioxane (CH2=CHSiO3/2) aerogels have been conducted. As previously reported, transparent polyvinylsilsesquioxane aerogels can be obtained by utilizing a liquid surfactant as a solvent and a two-step sol–gel reaction involving hydrolysis catalyzed by a strong acid and subsequent polycondensation by a strong base. In this study, effects of base catalyst, gelation and aging conditions, amount of surfactant and concentration of acid catalyst have been investigated. With the optimized synthetic condition, the value of light transmittance reaches as high as 70% (at the wavelength of 550 nm for a 10-mm thick sample). Applicability of addition reactions utilizing thiol-ene reactions and hydrosilylation has also been surveyed. Thiol-ene reactions are relatively effective and can modify surface hydrophobicity and mechanical properties of polyvinylsilsesquioxane aerogels. In the case of hydrosilylation, a partial addition of a hydrosilane compound onto the polyvinylsilsesquioxane gel surface can be observed. Addition reactions, in particular thiol-ene reactions, are found to be profitable for implementing chemical functionality on the transparent aerogels. Graphical Abstract: [InlineMediaObject not available: see fulltext.]

DOI： 10.1007/s10971-017-4339-6

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Flexible low-density materials, such as aerogels and polymer foams, have received increasing attention as energy absorbers and cushions that protect artificial products and human bodies. Microscopic geometry is a crucial factor determining their mechanical functions, i.e. strength and toughness (flexibility). However, it is a formidable challenge to combine these two properties because they are mutually elusive in general; stiff materials are brittle, while flexible ones are soft. Here, we demonstrate lightweight porous polymeric materials based on a common phenolic resin, resorcinol-formaldehyde (RF) gels, with salient combinatorial properties of high stiffness (up to 100 MPa) and good recoverable compressibility (against 80-90% strain), which can deliver remarkable energy absorption and dissipation performances repetitively. The detailed investigation reveals that the unique mechanical features originate from the synergetic effect of interdigitated hard and soft components in polymer matrices as well as exquisitely designed highly branched microstructures both generated through the spontaneous supramolecular self-assembly of the nonionic block copolymer (F127) and RF oligomer, which is essentially analogous to how natural organisms create biological structural materials, e.g. nacre and bone.

DOI： 10.1021/acs.chemmater.6b04706

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Multifunctional catalysts are of great interest in catalysis because their multiple types of catalytic or functional groups can cooperatively promote catalytic transformations better than their constituents do individually. Herein we report a new synthetic route involving the surface functionalization of nanoporous silica with a rationally designed and synthesized dihydrosilane (3-aminopropylmethylsilane) that leads to the introduction of catalytically active grafted organoamine as well as single metal atoms and ultrasmall Pd or Ag-doped Pd nanoparticles via on-site reduction of metal ions. The resulting nanomaterials serve as highly effective bifunctional dehydrogenative catalysts for generation of H2 from formic acid.

DOI： 10.1021/acsami.6b12972

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Polymethylhydrosiloxane has been grafted on the surface of a hierarchically porous silica monolith using a facile catalytic reaction between Si-H and silanol to anchor the polymer. This easy methodology leads to the functionalization of the surface of a silica monolith, where a large amount of free Si-H bonds remain available for reducing metal ions in solution. Palladium nanoparticles of 15 nm have been synthesized homogeneously inside the mesopores of the monolith without any stabilizers, using a flow of a solution containing Pd2+. This monolith was used as column-type fixed bed catalyst for continuous flow hydrogenation of styrene and selective hydrogenation of 3-hexyn-1-ol, in each case without a significant decrease of the catalytic activity after several hours or days. Conversion, selectivity, and stereoselectivity of the alkyne hydrogenation can be tuned by flow rates of hydrogen and the substrate solution, leading to high productivity (1.57 mol g(Pd)-1 h-1) of the corresponding cis-alkene.

DOI： 10.1021/acsami.6b12653

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Abstract: Low-density, transparent aerogels based on a hexylene-bridged polysilsesquioxane ([O1.5Si–(CH2)6–SiO1.5]n) network have been prepared for the first time via a simple sol–gel process. An optimized base-catalyzed one-step hydrolysis–polycondensation process of a bridged alkoxysilane precursor 1,6-bis(trimethoxysilyl)hexane in a low-polarity solvent N,N-dimethylformamide allows for the formation of a pore structure of a length scale of several tens nanometers, resulting in low-density, transparent aerogels after supercritical drying. Because of the incorporated organic moiety that bridges the silicon atoms in the network, these aerogels show higher flexibility and strength against compression and bending as compared to silica aerogel counterparts. In addition, minimizing the residual silanol groups in the network by a surface modification with hexamethyldisilazane has further improved resilience after compression and bending flexibility and strength, due to the decreased chance of the irreversible formation of the siloxane bonds upon compression. The resulting trimethylsilylated hydrophobic gels have been subjected to ambient pressure drying to obtain xerogels, resulting in low-density (0.13 g cm−3, 90 % porosity), transparent (71 % transmittance) xerogels. These results are promising for the development of transparent thermal superinsulators applicable to window insulating systems that manage heat transfer in a more efficient way. Graphical Abstract: [Figure not available: see fulltext.]

DOI： 10.1007/s10971-016-4077-1

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

Nanostructured amorphous silica in rice plants (biosilica or plant opal) plays an important role in plant growth related to food production. However, the same silica has a structural supporting role as well that has not been uncovered. The current study focuses on the structural design of the two main types of biosilicas in rice plants for the improvement of their mechanical properties. One structural motif is plate-like silicas, which cover most of the surfaces of leaf blades. Another is fan-shaped silicas, which are aligned inside leaf blades, providing a stiff backbone. These biosilica structures consist of 10-100 nm diameter nanoparticles. The mechanical properties, such as hardness and Young's modulus, of the biosilicas are associated with their relative density. Thus, the rice plant mechanics is inferred to be designed by changing the packing of the nanoparticles. Silica plates consisting of loosely packed particles have relatively low density and high flexibility enabling coverage of leaf blade surfaces, while fan-shaped silicas, which consist of tightly packed nanoparticles, are rigid to support the leaf blades as a backbone.

DOI： 10.1039/c6ra27317c

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymers and Polymer Composites  

Increasing the efficiency of encapsulation of ingredients into spherical capsules can decrease the manufacturing costs of the capsules. Ingredients can be encapsulated with high efficiency (>99%) into nondegradable hard resin capsules prepared by polymerization of spherical droplets of trimethylolpropane trimethacrylate (TRIM) monomer placed on a superoleophobic material. Poly(methyl methacrylate) (PMMA) resin is a more versatile capsule material than poly-TRIM resin. In this study, the efficiency of encapsulation in PMMA resin capsules prepared from methyl methacrylate (MMA) monomer was investigated. To reduce the volatility of the MMA monomer, pre-polymerized MMA was used for capsule preparation. Although non-volatile α-tocopherol and doxorubicin could be encapsulated in the capsules with high efficiency by heat polymerization at 60°C for 3 h, the efficiency for volatile tetradecane was much lower (approximately 60%) because it evaporated. Furthermore, even when using pre-polymerized MMA, more than 70% of the prepolymer evaporated during polymerization. To prevent the evaporation of tetradecane and the prepolymer, ultraviolet photopolymerization was adopted because it was faster and could be conducted at a lower temperature. The photopolymerization prevented the evaporation of the prepolymer and increased the efficiency of encapsulation of tetradecane (approximately 90% efficiency). This polymerization system is effective for encapsulation of ingredients in PMMA capsules with high efficiency.

DOI： 10.1177/096739111702500202

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Langmuir  

Transparent, monolithic aerogels with nanosized colloidal skeletons have been obtained from a single precursor of 1,2-bis(methyldiethoxysilyl)ethane (BMDEE) by adopting a liquid surfactant and a two-step process involving strong-acid, followed by strong-base, sol-gel reactions. This precursor BMDEE forms the ethylene-bridged polymethylsiloxane (EBPMS, O2/2(CH3)Si-CH2CH2-Si(CH3)O2/2) network, in which each silicon has one methyl, two bridging oxygens, and one bridging ethylene, exhibiting an analogous structure to that of the previously reported polymethylsilsesquioxane (PMSQ, CH3SiO3/2) aerogels having one methyl and three bridging oxygen atoms. Obtained aerogels consist of fine colloidal skeletons and show high visible-light transparency and a flexible deformation behavior against compression without collapse. Similar to the PMSQ aerogels, a careful tuning of synthetic conditions can produce low-density (0.19 g cm-3) and highly transparent (76% at 550 nm, corresponding to 10 mm thick samples) xerogels via ambient pressure drying by solvent evaporation due to their high strength and resilience against compression. Moreover, EBPMS aerogels exhibit higher bending strength and bending strain at break against the three-point bending mode compared to PMSQ aerogels. This improved bendability is presumably derived from the introduced ethylene-bridging parts, suggesting the potential for realizing transparent and bendable aerogels in such polysiloxane materials with organic linking units.

DOI： 10.1021/acs.langmuir.6b03249

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Catalysis Communications  

We report the application of hierarchically porous zirconium phosphate monoliths with high surface area as acidic heterogeneous catalysts for the dehydration of xylose into furfural. Analyses by NH3-temperature programmed desorption and 31P solid state NMR reveal the presence of both Lewis and Brønsted acid sites in the as-synthesized zirconium phosphate monolith and that calcined at 600 °C. High accessibility and availability of the acidic sites and easy separation of the monolith from the liquid medium result in good catalytic activity (initial reaction rate for furfural production as 8.7 mmol gcat− 1 h− 1) with easy handling of the catalyst.

DOI： 10.1016/j.catcom.2016.09.014

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Silica aerogels are unique porous materials possessing high visible-light transparency and low thermal conductivity. However, the practical applications are limited due to the native fragility of silica, and a lot of research focuses on the improvement of mechanical properties by organic-inorganic hybridization, and so forth. Here, the first synthesis of polyethylsilsesquioxane (PESQ; CH3CH2SiO1.5) and polyvinylsilsesquioxane (PVSQ; CH2 - CHSiO1.5) aerogels is reported. The resultant PESQ and PVSQ aerogels obtained through a two-step acid-base sol-gel reaction in a surfactant-based solution exhibit visible-light transmittance and flexibility against compression without collapsing. The microstructural variations of these aerogels are systematically investigated by positron annihilation lifetime spectroscopy (PALS) in order to clarify the differences in properties derived from substituent groups. Furthermore, a post cure on the PVSQ wet gel using a radical initiator induces polymerization of vinyl groups in the solid network, resulting in mechanically reinforced aerogels with higher compressive modulus and resilience. This chemical modification, similar to vulcanization in silicone rubber materials, helps to produce xerogels with comparable properties to those of aerogels via ambient pressure drying. Since the resultant xerogel obtained from the vulcanization of PVSQ shows sufficiently low thermal conductivity of 15.3 mW m-1 K-1, these novel polysilsesquioxane materials are promising for transparent aerogels/xerogels superinsulators.

DOI： 10.1021/acs.chemmater.6b01936

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

DOI： 10.1007/s10971-016-4124-y

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Porous Materials  

Yttria-stabilized zirconia monoliths with well-defined macropores and high porosity have been successfully fabricated via sol–gel process accompanied by phase separation. Propylene oxide acts as an acid consumer to mediate sol–gel process, and poly (ethylene oxide) is used to induce phase separation. Ethylene glycol is applied as chelating agent, and formamide serves as drying control chemical additive to inhibit cracking during drying stage. Proper proportion of the starting compositions allows the generation of well-defined macroporous YSZ monoliths with co-continuous skeletons and porosity as high as more than 60 %. The dried gels are amorphous and crystalline of ZrO2 precipitates after heat treatment between 400 and 1200 °C without formation of monoclinic ZrO2, which indicating a wide application prospects.

DOI： 10.1007/s10934-016-0143-x

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Power Sources  

Hard carbons emerge as one of the most promising candidate for an anode of Na-ion batteries. This research focuses on the carbon monolith derived from resorcinol-formaldehyde (RF) gels as a model hard carbon electrode. A series of binder-free monolithic carbon electrodes heat-treated at varied temperatures allow the comparative investigation of the correlation between carbon nanotexture and electrochemical Na+-ion storage. The increase in carbonization temperature exerts a favorable influence on electrode performance, especially in the range between 1600°C and 2500°C. The comparison between Li+- and Na+-storage behaviors in the carbon electrodes discloses that the Na+-trapping in nanovoids is negligible when the carbonization temperature is higher than 1600°C. On the other hand, the high-temperature sintering at 2500-3000°C enlarges the resistance for Na+-insertion into interlayer spacing as well as Na+-filling into nanovoids. In addition, the study on the effect of pore size clearly demonstrates that not the BET surface area but the surface area related to meso- and macropores is a predominant factor for the initial irreversible capacity. The outcomes of this work are expected to become a benchmark for other hard carbon electrodes prepared from various precursors.

DOI： 10.1016/j.jpowsour.2016.04.013

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

This report demonstrates a facile one-pot synthesis of hierarchically porous resorcinol-formaldehyde (RF) gels comprising mesoporous nanorod assemblies with two-dimensional (2D) hexagonal ordering by combining a supramolecular self-assembly strategy in the nanometer scale and phase separation in the micrometer scale. The tailored multilevel pore system in the polymer scaffolds can be preserved through carbonization and thermal activation, yielding the multimodal porous carbon and activated carbon (AC) monoliths. The thin columnar macroframeworks are beneficial for electrode materials due to the short mass diffusion length through small pores (micro- and mesopores). By employing the nanostructured AC monolith as a binder-free electrode for supercapacitors, we have also explored the capability of "water-in-salt" electrolytes, aiming at high-voltage aqueous supercapacitors. Despite that the carbon electrode surface is supposed to be covered with salt-derived decomposition products that hinder the water reduction, the effective surface area contributing to electric double-layer capacitance in 5 M bis(trifluoromethane sulfonyl)imide (LiTFSI) is found to be comparable to that in a conventional neutral aqueous electrolyte. The expanded stability potential window of the superconcentrated electrolyte allows for a 2.4 V-class aqueous AC/AC symmetric supercapacitor with good cycle performance.

DOI： 10.1021/acs.chemmater.6b01261

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

DOI： 10.1021/acs.chemmater.6b01010

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

A versatile synthetic method has been developed for the fabrication of metal zirconium phosphate (MZP) macroporous monoliths via a sol-gel process accompanied by phase separation. More than 30 kinds of MZP monolithic polycrystalline monoliths with co-continuous macroporous structure have been synthesized by simply adding the target metal salt in the starting solution with optimized compositions. Glycerol, due to its high boiling point, plays the key role as the solvent to prevent metal salt from recrystallization, allowing a homogeneous distribution of metal salts over the polymerizing zirconium phosphate network. Hierarchically porous polycrystalline strontium zirconium phosphate (SrZrP) monolith has been obtained when the dried gel was calcined at 1000 °C. Very low thermal expansion (coefficient of thermal expansion (CTE) as 1.4 × 10-6 K-1) over a wide temperature range (38 °C-1000 °C) together with good mechanical properties (flexural modulus as 8.0 GPa from 3 point bending test and Young's modulus as 1.9 GPa from uniaxial compression test) has been demonstrated, while high porosity (43%) due to the presence of macropores reduces bulk density. As compared with dense ceramics of the same composition, the CTE value is lower and can be attributed to the presence of nanometer-sized small pores, which absorbs the anisotropic thermal expansion of each crystallite in the macropore skeletons at elevated temperatures.

DOI： 10.1016/j.micromeso.2015.12.002

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer Bulletin  

Spherical capsules have been used in various fields because of their many advantages. In many industrial applications, hydrophobic hard resins (e.g., polyacrylate, epoxy and polystyrene) are used as a shell material for stable packaging of ingredients within capsules. However, it is difficult to encapsulate ingredients in such capsules without loss by conventional techniques. The purpose of this study was to encapsulate hydrophobic ingredients within polyacrylate resin capsules with ultrahigh efficiency. In our methodology, a small volume of resin monomer solution containing the ingredients was first placed on a superoleophobic material and the resulting spherical droplets were then solidified by polymerization of the monomer. Doxorubicin (an anticancer drug), α-tocopherol (an antioxidant) and tetradecane (a phase change material used for heat storage) could be encapsulated in spherical hard capsules with almost no loss by heat and photopolymerization. We showed that tetradecane in the capsules had almost identical thermal properties to pure tetradecane. These results demonstrate that our technique is promising for encapsulation of hydrophobic ingredients in hard resin capsules.

DOI： 10.1007/s00289-015-1497-y

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

The performance of flow-through particles has been studied by computational fluid dynamics. Computational fluid dynamics simulations was used to calculate the flow behaviour around and inside the particles rather than estimate it. The obtained flow field has been used to accurately simulate plate heights generated by flow-through particles and compare them to standard fully porous particles. The effects of particle size, particle porosity and microparticle size on the intra-particle flow and plate heights is investigated. It is shown that the intra-particle flow generates mass transfer enhancement which lowers the total plate height. An empirical model is proposed for the mass transfer enhancement and it is compared to previously proposed models. Kinetic plots are constructed for the flow-through particles. Counter-intuitively, columns packed with flow-through particles have a higher flow resistance which counters the advantages of lower plate heights. Flow-through particles offer no significant gain in kinetic performance over fully porous particles.

DOI： 10.1016/j.chroma.2015.12.019

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Hierarchically porous titanium phosphate monoliths combining well-defined co-continuous macropores and accessible large mesopores have been synthesized for the first time via a sol-gel process accompanied by phase separation using titanium oxysulfate and phosphoric acid as precursors. The macropore size was tunable over a broad range from 0.6 μm to 10 μm by changing the starting composition, while the mesopore size and the specific surface area of the as-synthesized amorphous monoliths are 21 nm and 320 m2 g-1, respectively. Crystallization of the gel network can be induced in two different ways. Calcination at elevated temperature (800 °C) leads to the formation of TiP2O7 and the collapse of both the macro- and meso-structures, while the solvothermal treatment of the as-synthesized gel in ethylene glycol leads to the formation of platy crystals of titanium phosphate with a layered structure at relatively low temperature. The titanium phosphate monoliths with a hierarchically porous structure are expected to be useful in various applications such as continuous-flow catalysis, water remediation and ion batteries.

DOI： 10.1039/c5nj02820e

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ChemElectroChem  

Hard carbons have immense potential as anode materials for Na-ion batteries, because the expanded graphene interlayers and nanovoids between randomly stacked aromatic fragments can accommodate a substantial amount of sodium. However, the large irreversible capacity in the first cycle still remains as a significant issue in terms of a practicable battery technology. Here, we show that hard carbon electrodes derived from a common phenol resin deliver a high reversible capacity within the narrow potential range of 0.1-0.005V (vs. Na+/Na) and an excellent initial coulombic efficiency up to 95%. The former allows the sustainable high voltage, whereas the latter minimizes the amount of unavailable Na+ in a closed cell. The findings in this work put forward a guideline for manufacturing hard carbon electrodes, which goes against the current trend of nanostructuring and downsizing. It's got potential: Carbon electrodes derived from a phenol resin for Na-ion batteries show potential profiles just like those of Li-ion intercalation/extraction into/from graphite. The high reversible capacity and the excellent initial coulombic efficiency well above 90% have great potential for a practical use.

DOI： 10.1002/celc.201500412

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

Solgel synthesis of macroporous polymethylsilsesquioxane (PMSQ) monoliths has been successful over the past decade, and applications to separation media have been investigated. However, the control of mesopores to tailor hierarchical porosity, which is promising for improvement of the separation efficiency, remains challenging. In particular, an independent control of mesoand macropores has not been achieved in PMSQ. Herein we present a method to synthesize PMSQ monoliths with well-defined macropores and controlled mesostructure (pore size ranging from 10 to 60 nm, total pore volume from 0.2 to 0.6 cm3 g-1) via solgel accompanied by phase separation. Different Pluronic-type nonionic surfactants were used to control phase separation of the hydrophobic PMSQ network in aqueous media. Due to different packing density of the colloidal PMSQ constituents in the continuous skeletons in the micrometer-scale (termed as macropore skeletons) and their rearrangements through the hydrothermal post-treatment under basic conditions, mesopore characteristics have been successfully controlled independently of the preformed macropore structure. Separation columns for high-performance liquid chromatography (HPLC) have been fabricated using the PMSQ monoliths, and acceptable separation performances in both the reversed-phase and normal-phase modes have been demonstrated due to the presence of both hydrophilic silanol groups and hydrophobic methyl groups.

DOI： 10.2109/jcersj2.123.770

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

Conventionally, commercialized spherical silicone powders, such as silicone resin powder [INCI: POLYMETHYLSILSESQUIOXANE (PMSQ beads)]1) and silicone rubber powder [INCI: DIMETHICONE/VINYL DIMETHICONE CROSSPOLYMER (DVDC beads)],2) have been formulated into cosmetics for soft and smooth feeling. Due to the low crosslink density, silicone rubber powder shows soft touch and high oil absorption. However, it is too agglomerative to be formulated into powder foundation. In this work, we have developed the novel soft touch spherical silicone beads made from methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS), using a surfactant, cetyltrimethylammonium chloride (CTAC). The preparation procedure of the novel silicone beads requires only homogeneous mixing and includes no other complicated operations. The 29Si NMR and TG measurements indicate that DMDMS is randomly incorporated into the methylsiloxane network. The particle size of the beads can be controlled by the concentration of urea as well as by the stirring speed in the solgel reaction. By carefully adjusting these parameters, the size of the beads has been optimized for the use in make-up cosmetics. It was revealed by various evaluation measurements that the novel silicone beads exhibit unique characteristics, such as softness, low oil absorption, high transparency and light diffusion effects.

DOI： 10.2109/jcersj2.123.714

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Separation Science  

The optimization of a porous structure to ensure good separation performances is always a significant issue in high-performance liquid chromatography column design. Recently we reported the homogeneous embedment of Ag nanoparticles in periodic mesoporous silica monolith and the application of such Ag nanoparticles embedded silica monolith for the high-performance liquid chromatography separation of polyaromatic hydrocarbons. However, the separation performance remains to be improved and the retention mechanism as compared with the Ag ion high-performance liquid chromatography technique still needs to be clarified. In this research, Ag nanoparticles were introduced into a macro/mesoporous silica monolith with optimized pore parameters for high-performance liquid chromatography separations. Baseline separation of benzene, naphthalene, anthracene, and pyrene was achieved with the theoretical plate number for analyte naphthalene as 36 000 m-1. Its separation function was further extended to cis/trans isomers of aromatic compounds where cis/trans stilbenes were chosen as a benchmark. Good separation of cis/trans-stilbene with separation factor as 7 and theoretical plate number as 76 000 m-1 for cis-stilbene was obtained. The trans isomer, however, is retained more strongly, which contradicts the long- established retention rule of Ag ion chromatography. Such behavior of Ag nanoparticles embedded in a silica column can be attributed to the differences in the molecular geometric configuration of cis/trans stilbenes.

DOI： 10.1002/jssc.201500444

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

The present report demonstrates a new technique for doping heteroatoms (nitrogen, phosphorus, and sulfur) into carbon materials via a versatile post-treatment. The heat-treatment of carbon materials with a reagent, which is stable at ambient temperatures and evolves reactive gases on heating, in a vacuum-closed tube allows the introduction of various heteroatom-containing functional groups into a carbon matrix. In addition, the sequential doping reactions give rise to dual- and triple-heteroatom-doped carbons. The pore properties of the precursor carbon materials are preserved through each heteroatom doping process, which indicates that independent tuning of heteroatom doping and nanostructural morphology can be achieved in various carbon materials. The electrochemical investigation on the undoped and doped carbon monolithic electrodes applied to supercapacitors provides insights into the effects of heteroatom doping on electrochemical capacitance. (Figure Presented).

DOI： 10.1021/acs.chemmater.5b01349

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1021/acs.inorgchem.5b00810

Web of Science

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Science and Technology of Advanced Materials  

Monolithic macroporous zirconia (ZrO<inf>2</inf>) derived from ionic precursors has been successfully fabricated via the epoxide-mediated sol-gel route accompanied by phase separation in the presence of propylene oxide (PO) and poly(ethylene oxide) (PEO). The addition of PO used as an acid scavenger mediates the gelation, whereas PEO enhances the polymerization-induced phase separation. The appropriate choice of the starting compositions allows the production of a macroporous zirconia monolith with a porosity of 52.9% and a Brunauer-Emmett-Teller (BET) surface area of 171.9 m² · g^-1. The resultant dried gel is amorphous, whereas tetragonal ZrO<inf>2</inf> and monoclinic ZrO<inf>2</inf> are precipitated at 400 and 600 °C, respectively, without spoiling the macroporous morphology. After solvothermal treatment with an ethanol solution of ammonia, tetragonal ZrO<inf>2</inf> monoliths with smooth skeletons and well-defined mesopores can be obtained, and the BET surface area is enhanced to 583.8 m² · g^-1.

DOI： 10.1088/1468-6996/16/2/025003

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inorganic Chemistry  

A preceramic polymer route from Ti-based inorganic-organic hybrid networks provides electroconductive N-doped reduced titanium oxides (Ti n O 2n-1 ) and titanium oxynitrides (TiO x N y ) with a monolithic shape as well as well-defined porous structures. This methodology demonstrates an advantageously lower temperature of the crystal phase transition compared to the reduction of TiO 2 by carbon or hydrogen. In this study, the effect of calcination conditions on various features of the products has been explored by adopting three different atmospheric conditions and varying the calcination temperature. The detailed crystallographic and elemental analyses disclose the distinguished difference in the phase transition behavior with respect to the calcination atmosphere. The correlation between the crystallization and nitridation behaviors, porous properties, and electric conductivities in the final products is discussed.

DOI： 10.1021/ic502972v

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

Prototype small-size (1.0mm I.D., 5cm long) columns for reversed-phase HPLC were evaluated in relation to instrument requirements. The performance of three types of columns, monolithic silica and particulate silica (2μm, totally porous and 2.6μm, core-shell particles) was studied in the presence of considerable or minimal extra-column effects, while the detector contribution to band broadening was minimized by employing a small size UV-detector cell (6- or 90nL). A micro-LC instrument having small system volume (<1μL) provided extra-column band variance of only 0.01-0.02μL2. The three columns generated about 8500 theoretical plates for solutes with retention factor, k>1-3 (depending on the column), in acetonitrile/water mobile phase (65/35=vol/vol) at 0.05mL/min, with the instrument specified above. The column efficiency was lower by up to 30% than that observed with a 2.1mm I.D. commercial column. The small-size columns also provided 8000-8500 theoretical plates for well retained solutes with a commercial ultrahigh-pressure liquid chromatography (UHPLC) instrument when extra-column contributions were minimized. While a significant extra-column effect was observed for early eluting solutes (k<2-4, depending on column) with methanol/water (20/80=vol/vol) as weak-wash solvent, the use of methanol/water=50/50 as wash solvent affected the column efficiency for most analytes. The results suggest that the band compression effect by the weak-wash solvent associated with partial-loop injection may provide a practical means to reducing the extra-column effect for small-size columns, while the use of an instrument with minimum extra-column effect is highly desirable.

DOI： 10.1016/j.chroma.2015.01.014

Web of Science

Scopus

PubMed

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

DOI： 10.1021/cm503993n

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Energy Materials  

Integrated design of both porous structure and crystalline morphology is expected to open up the way to a new class of materials. This report demonstrates new nanostructured Li4Ti5O12 materials with hierarchically porous structures and flower-like morphologies. Electrochemical studies of the electrodes of Li-ion and Na-ion batteries clearly reveal the advantage of nanoarchitectural design of active materials. In addition, the temperature dependence of Na+-insertion/extraction capacity in relation to Li4Ti5O12 electrodes is for the first time evaluated and it is found that elevation of the cell operating temperature effectively improves the rate capability of the Na-ion batteries. Based on the new findings, it is suggested that specially designed Li4Ti5O12 materials allow for high-performance Na-ion batteries that are available as large-scale storage devices for applications such as automotive and stationary energy storage.

DOI： 10.1002/aenm.201400730

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Copper hydroxide-based monolithic xerogels with controlled hierarchical pores have been prepared directly by a sol-gel process from an ionic precursor, CuCl2·2H2O. Propylene oxide acts as a gelation inducer by increasing pH homogeneously in a reaction solution. Poly(acrylamide) is utilized not only to control macroscopic phase separation but also to support the network physically. Glycerol contributes to the formation of monolithic gels by suppressing the growth of copper hydroxide crystals. An appropriate starting composition leads to co-continuous gel skeletons and macropores. Although the as-dried gels were amorphous, post-treatments (calcination and solvothermal treatment) formed metallic copper and copper oxides (CuO and Cu2O) without the collapse of the monolithic form and macrostructure.

DOI： 10.1039/c5nj00479a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemical Communications  

The synthesis of highly crystalline macro-meso-microporous monolithic Cu3(btc)2 (HKUST-1; btc3- = benzene-1,3,5-tricarboxylate) is demonstrated by direct conversion of Cu(OH)2-based monoliths while preserving the characteristic macroporous structure. The high mechanical strength of the monoliths is promising for possible applications to continuous flow reactors. This journal is

DOI： 10.1039/c4cc09694k

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemical Science  

The coordination replication technique is employed for the direct conversion of a macro- and mesoporous Cu(OH)<inf>2</inf>-polyacrylamide composite to three-dimensional superstructures consisting of the flexible porous coordination polymers, Cu<inf>2</inf>(bdc)<inf>2</inf>(MeOH)<inf>2</inf> and Cu<inf>2</inf>(bdc)<inf>2</inf>(bpy) (bdc^2- = 1,4-benzenedicarboxylate, bpy = 4,4′-bipyridine). Detailed characterization of the replicated systems reveals that the structuralization plays an important role in determining the adsorptive properties of the replicated systems, and that the immobilization of the crystals within a higher-order architecture also affects its structural and dynamic properties. The polyacrylamide polymer is also found to be crucial for maintaining the structuralization of the monolithic systems, and in providing the mechanical robustness required for manual handling. In all, the results discussed here demonstrate a significant expansion in the scope of the coordination replication strategy, and further confirms its utility as a highly versatile platform for the preparation of functional three-dimensional superstructures of porous coordination polymers.

DOI： 10.1039/c5sc02034d

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Hierarchically porous AlPO4 monoliths with well-defined macropores are prepared via a sol-gel process accompanied by phase separation. Appropriate amounts of the precursors, poly(ethylene oxide) and propylene oxide, allow the formation of a mesoporous structure with uniform macropore size distribution in the gel. A crystalline phase of tridymite forms after heat-treatment at 1000 °C in air, while the meso- and macro-porous structure is preserved, maintaining a BET surface area of 120.8 m2 g-1. The resultant crystalline AlPO4 monolith is used as the host to immobilize silver nanoparticles (Ag NPs) by immersing it in silver colloid under an ambient condition. The result shows that Ag NPs were homogeneously embedded on the surface of skeletons without spoiling the appearance and macroporous structure of the initial AlPO4 monolith. Ag NPs embedded in monolithic AlPO4 show promise in a wide range of applications, including catalysis and separation.

DOI： 10.1039/c5nj00490j

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Dalton Transactions  

Hierarchically porous silica monoliths with well-defined interconnected macropores and uniform spherical mesopores were spontaneously prepared by combining polymerization-induced phase separation with an epoxide-mediated sol-gel route without any complicated aging and drying and high-temperature heat treatment. The precise control of pore structures can be realized by using propylene oxide (PO) as the gelation mediation agent, poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (P123) as the phase-separation inducer as well as the structure-directing agent and 1,3,5-trimethylbenzene (TMB) as the micelle-swelling agent. The as-prepared silica monolith possesses an interesting hierarchically porous structure constructed by 10 nm uniform spherical mesopores confined in a macroporous framework of well-defined 1 μm macropores, and exhibits a BET surface area as high as 848 m2 g-1. Heat treatment at 400-800 °C gradually decreases the BET surface area to 195 m2 g-1, while most of the uniform mesoporous structure remains intact.

DOI： 10.1039/c5dt01672j

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

Hierarchically porous TiO2 based composites (pure TiO2 and TiO2/carbon (TiO2/C) composite) were synthesized by a facile sol-gel process followed by post-calcination. Poly(vinylpyrrolidone) (PVP) acts as a phase separation inducer as well as a carbon source. The as-prepared TiO2 based composites possess an interesting hierarchically porous structure constructed of cocontinuous macropores and mesoporous skeletons consisting of interconnected nanocrystals and in situ distributed carbon. The hierarchically porous TiO2/C composite shows excellent electrochemical performance with fast lithium ion diffusion and electronic transport, resulting from the hierarchically porous structure and conductive carbon material. The TiO2/C composite calcined at 500°C exhibits the highest BET surface area of 170 m2 g-1, superior cycling stability (delivers a remarkable discharge capacity of 132 mA h g-1 at 1 C after 100 cycles) and excellent rate capability (over 96 mA h g-1 at 30 C rate). The results indicate that these hierarchically porous TiO2 based composites could be promising anode materials for high performance lithium ion batteries.

DOI： 10.1039/c5ra03491d

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Electrochemical Society  

We report the fabrication of porous titanium nitride (TiN) monoliths through the ammonolysis of porous TiO2 monoliths prepared via the sol-gel process accompanied by phase separation. The obtained TiN monoliths possess good mechanical strength as well as excellent electric conductivity with a superconducting transition at Tc ~ 5.0 K. We have investigated the electrochemical properties of the porous TiN monoliths as an electrode using various electrolytes. The results reveal that the pseudocapacitance of TiN increases in the order of K+ < Na+ < Li+ contrary to the case of EDL capacitance in neutral aqueous electrolytes. It is also found that acidic and strongly basic electrolytes are not suitable due to high corrosivity, while there is no significant deterioration when neutral aqueous electrolytes and organic electrolytes are used.

DOI： 10.1149/2.0491501jes

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

Removal of toxic substances from industrial wastes is an urgent issue for realizing a sustainable society. Layered double hydroxides (LDHs) are expected to be an effective adsorbent for toxic anions, especially oxyanions, because of their high anion adsorption capacity and reusability. Monolithic LDH materials with rational meso- and macropores are expected to show high adsorption capacity/rate towards targeted toxic substances owing to their large specific surface area and liquid transport property. Besides fabricating hierarchical pores, size control of microcages in LDH crystals is required to achieve selective removal of oxyanions. Herein, we prepared hierarchically porous monolithic LDH composites with tunable microcages by changing the combination of cationic species in the LDH crystal. Monolithic Mg-, Mn-, Fe-, Co- and Ni-Al type LDH composites with hierarchical pores were successfully prepared via an epoxide-mediated sol-gel reaction accompanied with phase separation. The monolithic Co-Al type LDH composite with hierarchical pores exhibited the highest CrO<inf>4</inf>^2- adsorption capacity because its microcage size easily fits the CrO<inf>4</inf>^2- size. Also Co-Al type LDH composites adsorbed different oxyanions, depending on their affinity with the LDH, in a SO<inf>4</inf>^2-, CrO<inf>4</inf>^2-, MoO<inf>4</inf>^2- and HVO<inf>4</inf>^2- co-existing solution. The pore size controllability in discrete length-scales of micrometers, nanometers, and picometers offers LDHs with tailored surface chemistries and physical properties desirable for effective and selective oxyanion adsorption.

DOI： 10.1039/c5ra05942a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Hierarchically porous monolithic materials are advantageous as adsorbents, catalysts and catalyst supports due to the better accessibility of reactants to the active sites and the ease of recycle and reuse. Traditional synthetic routes, however, have limitations in designing hierarchical porosity as well as the mechanically stable monolithic shape in inorganic phosphate materials, which are useful as adsorbents and catalysts. We present a low-temperature, one-step liquid phase synthesis of hierarchically porous zirconium phosphate (ZrP) monoliths with tunable compositions (from Zr(HPO4)2 (Zr:P = 1:2) to NaSICON (Na super ionic conductor)-type ZrP (Zr:P = 1:1.5)) as well as macropore size (from 0.5 to 5 μm). The as-synthesized ZrP monolith with a high reactive surface area (600 m2 g-1) and relatively high mechanical strength (Young's modulus 320 MPa) was applied to ion adsorption. A simple syringe device inserted tightly with the ZrP monolith as a continuous flow setup was demonstrated to remove various toxic metal ions in aqueous solutions, which shows promising results for water purification.

DOI： 10.1039/c4nj01749h

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Monolithic mayenite with well-defined macropores has been successfully synthesized from ionic precursors via a sol-gel process accompanied by phase separation. The addition of propylene oxide (PO) to the starting solution leads to homogenous gelation and modifies the gel skeleton, whereas the addition of poly(ethylene oxide) (PEO) induces phase separation. Glycol acts as a chelating agent to suppress the precipitation of Ca2+ ions, and formamide works as a drying control chemical additive to enhance the drying behavior. Appropriate amounts of solvents, PEO, and PO allow the formation of calcium aluminate gels with co-continuous macroporous structure. The reaction mechanism of the sol-gel process of the Ca-Al-O system is also investigated by TG-DSC, FT-IR and NMR. The dried gels are amorphous and the crystalline phase Ca12Al14O32Cl2 forms after heat-treatment at 1000 °C in air, while the macroporous structure is preserved. The resultant monoliths before and after heat-treatment possess both high porosity and smooth and dense skeletons. This journal is

DOI： 10.1039/c4nj00898g

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Dalton Transactions  

A facile and "green" method was proposed to introduce Ag nanoparticles (Ag NPs) into the hierarchically monolithic silica uniformly in the presence of (3-aminopropyl)-triethoxysilane (APTES) and ethylene glycol. APTES is used to modify the monolith by incorporating amino groups onto the surface of meso-macroporous skeletons, while ethylene glycol is employed as the productive reductant. Ag NPs are homogeneously immobilized in hierarchically monolithic silica after reduction and drying at 40 °C for different duration times, and the embedded amount of Ag NPs can reach 15.44 wt% when treated once. The embedment of Ag NPs increases with the repeat treatment and the APTES amount, without uncontrollable crystalline growth. The surface areas of Ag NPs embedded in silica monoliths after heat treatment at 300 and 400 °C are higher than those before heat treatment. The modification via APTES and the embedment of Ag NPs does not spoil the morphology of monolithic silica, while changing the pore structures of the monolith. A tentative formation process and a reduction mechanism are proposed for the modification, reduction and embedment. Ag NPs embedded in monolithic silica is promising for wide applications such as catalysis and separation. This journal is © the Partner Organisations 2014.

DOI： 10.1039/C4DT00655K

Web of Science

Scopus

PubMed

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

Effective medium theory (EMT) expressions for the B-term band broadening in monolithic silica columns are presented at the whole-column as well as at the mesoporous skeleton level. Given the bi-continuous nature of the monolithic medium, regular as well as inverse formulations of the EMT-expressions have been established. The established expressions were validated by applying them to a set of experimental effective diffusion (Deff)-data obtained via peak parking on a number of 1st and 2nd generation monolithic silica columns, as well as to a set of numerical diffusion simulations in a simplified monolithic column representation (tetrahedral skeleton model) with different external porosities and internal diffusion coefficients. The numerically simulated diffusion data can be very closely represented over a very broad range of zone retention factors (up to k″=80) using the established EMT-expressions, especially when using the inverse variant. The expressions also allow representing the experimentally measured effective diffusion data very closely. The measured Deff/Dmol-values were found to decrease significantly with increasing retention factor, in general going from about Deff/Dmol=0.55 to 0.65 at low k″ (k″≅1.5-3.8) to Deff/Dmol=0.25 at very high k″ (k″≅40-80). These values are significantly larger than observed in fully-porous and core-shell particles. The intra-skeleton diffusion coefficient (Dpz) was typically found to be of the order of Dpz/Dmol=0.4, compared to Dpz/Dmol=0.2-0.35 observed in most particle-based columns. These higher Dpz/Dmol values are the cause of the higher Deff/Dmol values observed. In addition, it also appears that the higher internal diffusion is linked to the higher porosity of the mesoporous skeleton that has a relatively open structure with relatively wide pores. The observed (weak) relation between Dpz/Dmol and the zone retention factor appears to be in good agreement with that predicted when applying the regular variant of the EMT-expression directly to the mesoporous skeleton level. © 2014 Elsevier B.V.

DOI： 10.1016/j.chroma.2014.04.099

Web of Science

Scopus

PubMed

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Polymethylsilsesquioxane-cellulose nanofiber (PMSQ-CNF) composite aerogels have been prepared through sol-gel in a solvent containing a small amount of CNFs as suspension. Since these composite aerogels do not show excessive aggregation of PMSQ and CNF, the original PMSQ networks are not disturbed. Composite aerogels with low density (0.020 g cm-3 at lowest), low thermal conductivity (15 mW m-1 K-1), visible light translucency, bending flexibility, and superhydrophobicity thus have been successfully obtained. In particular, the lowest density and bending flexibility have been achieved with the aid of the physical supporting effect of CNFs, and the lowest thermal conductivity is comparable with the original PMSQ aerogels and standard silica aerogels. The PMSQ-CNF composite aerogels would be a candidate to practical high-performance thermal insulating materials. © 2014 American Chemical Society.

DOI： 10.1021/am501822y

Web of Science

Scopus

PubMed

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the European Ceramic Society  

Monolithic cordierite with a cocontinuous macroporous structure has been successfully prepared by the sol-gel process accompanied by phase separation in the presence of poly(acrylamide) (PAAm). Propylene oxide (PO) acts as an acid scavenger to mediate the gelation of MgO-Al2O3-SiO2 ternary system, while PAAm works as a phase-separation inducer as well as a network former. The dried gel and that heat-treated at 800°C are amorphous, and the sapphirine begins to precipitate at 900°C, then transforming to orthorhombic β-cordierite at 1100°C. After heat-treated at and above 1200°C, the resultant β-cordierite further transforms to stable hexagonal α-cordierite. Heat-treatment changes the macroporous structure of cordierite monoliths such as macropore size and its distribution. The macroporous cordierite monolith after heat-treated at 1200°C is found to possess a total porosity of 54%, interconnected macropores and dense solid skeletons. © 2013 Elsevier Ltd.

DOI： 10.1016/j.jeurceramsoc.2013.08.016

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the European Ceramic Society  

In this study, hierarchically porous bicrystalline nitrogen-doped titania (N-doped TiO2) monolithic material was fabricated by a simple two-step approach: (i) preparation of TiO2 porous monolith by a sol-gel process of titanium alkoxide in a mild condition utilizing a chelating agent and mineral salt and (ii) annealing of TiO2 porous monolith obtained under a modest flow of ammonia gas at 700°C for 2h. The phase composition, crystal structure, morphology, pore structure, and porous properties of the final product were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), mercury porosimetry, and nitrogen physisorption measurement, respectively. The resultant N-doped TiO2 porous monolith possesses a bicrystalline (anatase and rutile) framework with a well-defined macroporosity. The results from X-ray photoelectron spectroscopy (XPS) confirm the formation of OTiN bonds in the N-doped TiO2 porous monolith. The photocatalytic activity of N-doped TiO2 porous monolith was evaluated by the photodegradation of Rhodamine B over the samples under visible light. Nearly 50% of Rhodamine B in aqueous solution was efficiently degraded by N-doped TiO2 porous monolith with the mixed-phase of anatase and rutile under visible light within 120min. © 2013 Elsevier Ltd.

DOI： 10.1016/j.jeurceramsoc.2013.10.009

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Macromolecular Rapid Communications  

The direct synthesis of structurally well-defined protic polymeric ionic liquid (PIL) with controlled molecular weight and molecular weight distribution is examined using N,N-diethyl-N-(2-methacryloylethyl) ammonium bis(tri-fluoromethylsulfonyl)imide (DEMH-TFSI) as a monomer. Three polymerization methods, namely, atom transfer radical polymerization (ATRP), activators regenerated by electron transfer (ARGET)-ATRP, and organotellurium-mediated living radical polymerization (TERP) are employed in this study. While the polymerization by ATRP is slow and does not reach high monomer conversion that under ARGET-ATRP and TERP proceeds smoothly and affords structurally well-defined poly(DEMH-TFSI)s. TERP is especially efficient for the control and poly(DEMH-TFSI)s with low to high molecular weights (M̄n = 49 100-392 500) and narrow molecular weight distributions (M̄w/M̄n = 1.17-1.46) are obtained. These results represent the first example of synthesis of a structurally well-defined protic, ammonium PIL by direct polymerization of the protic ionic liquid monomer. The polymerization of N,N-diethyl-N-(2- methacryloylethyl)-N-methylammonium bis(trifluoromethylsulfonyl)imide (DEMM-TFSI), which possesses a quaternary ammonium salt, also proceeds in a highly controlled manner under TERP conditions. A diblock copolymer, polystyrene-block-poly(DEMH-TFSI), is also successfully synthesized by TERP. Structurally well-defined protic polymeric ionic liquid is prepared by the direct polymerization of protic ammonium-salt ionic liquid monomers, N,N-diethyl-N-(2-methacryloylethyl) ammonium bis(tri-fluoromethylsulfonyl)imide (DEMH-TFSI), under ARGET-ATRP and TERP conditions. TERP is especially suitable for the controlled polymerization and afforded poly(DEMH-TFSI) with low to high molecular weight (M̄n = 49 100-392 500) and a narrow molecular weight distribution (M̄w/M̄n = 1.17-1.46). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/marc.201300855

Scopus

PubMed

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Letters  

Macroporous TiO2 monolith was first prepared by the sol-gel method and then macroporous TiO2-SrTiO3 heterostructured monolith was obtained by the impregnation of the as-prepared macroporous TiO2 monolith in the strontium-containing aqueous solution followed by calcination at different temperatures. The formation of SrTiO3 crystals in the TiO2 network was confirmed by X-ray diffraction and electron microscopy analyses. Macroporous structure of the heterostructured monolith was analyzed by mercury porosimetry. The photocatalytic activity of macroporous TiO2-SrTiO3 heterostructured monolithic photocatalyst was evaluated for the photodegradation of Rhodamine B over the samples under visible light irradiation. The obtained results reveal that the samples show an enhanced photocatalytic activity for the degradation of organic dye molecules. © 2013 Elsevier B.V.

DOI： 10.1016/j.matlet.2013.11.065

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

The kinetic performance of commercially available first generation and prototype second generation silica monoliths has been investigated for 2.0mm and 3.0-3.2mm inner diameter columns. It is demonstrated that the altered sol-gel process employed for the production of second generation monoliths results in structures with a smaller characteristic size leading to an improved peak shape and higher efficiencies. The permeability of the columns however, decreases significantly due to the smaller throughpore and skeleton sizes. Scanning electron microscopy pictures suggest the first generation monoliths have cylindrical skeleton branches, whereas the second generation monoliths rather have skeleton branches that resemble a single chain of spherical globules. Using recently established correlations for the flow resistance of cylindrical and globule chain type monolithic structures, it is demonstrated that the higher flow resistance of the second generation monoliths can be entirely attributed to their smaller skeleton sizes, which is also evident from the external porosity that is largely the same for both monolith generations (e{open}e~0.65). The recorded van Deemter plots show a clear improvement in efficiency for the second generation monoliths (minimal plate heights of 13.6-14.1μm for the first and 6.5-8.2μm for the second generation, when assessing the plate count using the Foley-Dorsey method). The corresponding kinetic plots, however, indicate that the much reduced permeability of the second generation monoliths results in kinetic performances (time needed to achieve a given efficiency) which are only better than those of the first generation for plate counts up to N~45,000. For more complex samples (N≥50,000), the first generation monoliths can intrinsically still provide faster analysis due to their high permeability. It is also demonstrated that - despite the improved efficiency of the second generation monoliths in the practical range of separations (N=10,000-50,000) - these columns can still not compete with state-of-the-art core-shell particle columns when all columns are evaluated at their own maximum operating pressure (200bar for the monolithic columns, 600bar for core-shell columns). It is suggested that monolithic columns will only become competitive with these high efficiency particle columns when further improvements to their production process are made and their pressure resistance is raised. © 2013 Elsevier B.V.

DOI： 10.1016/j.chroma.2013.11.047

Web of Science

Scopus

PubMed

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

High-performance thermal insulating materials are desired especially from the viewpoint of saving energy for a sustainable society. Aerogel is the long-awaited material for extended applications due to its excellent thermal insulating ability. These materials are, however, seriously fragile against even small mechanical stress due to their low density, and their poor mechanical properties inhibit their practical use as superinsulators. In this paper, we report relationships between the thermal conductivity, pore size and mechanical properties of organic-inorganic hybrid polymethylsilsesquioxane (PMSQ) aerogels with improved mechanical properties and controllable pore sizes from ∼50 nm to 3 μm. The dependency of thermal conductivity on gas pressure and pore properties can be well explained by the thermal conduction theory of porous materials. These PMSQ aerogels show improved mechanical properties due to their elastic networks, which enable easier handling compared to conventional aerogels and facile production by simple ambient pressure drying. An aerogel-like "xerogel" monolithic panel has been successfully prepared via ambient pressure drying, which shows a low thermal conductivity (0.015 W m-1 K-1) comparable with those of the corresponding PMSQ aerogel and conventional silica aerogels. These results would open the gate for practical applications of these porous materials. This journal is © the Partner Organisations 2014.

DOI： 10.1039/c3ta15094a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

Hierarchically porous layered double hydroxide (LDH) materials have potential in anion-exchange, adsorption and catalysis applications, because of their large surface areas and liquid transportation capabilities. The preparation of monolithic LDH-Al(OH)3 composites with hierarchical μm and nm-scale channels and their adsorption behavior is reported. Monolithic gels were synthesized via sol-gel processing, from metal salt precursor solutions. μm-scale macrochannels spontaneously formed by inducing phase separation during sol-gel transition. nm-scale mesochannels were accommodated as interstices between primary/secondary particles. In this study, these hierarchical channel sizes were controlled. The macrochannel size was controlled by tuning the degree of phase separation. The mesochannel size was controlled independently, by tuning the crystallite size of LDH under different solvothermal conditions. The relationship between pore characteristics and adsorption behavior of tailored hierarchically porous LDH-Al(OH)3 monolithic gels were investigated by using dye molecules as adsorbates. Monolithic gels with larger macrochannels and mesochannels exhibit faster adsorption rate and higher affinity, respectively. LDH-Al(OH)3 monolithic gels with hierarchical channels may have potential in some applications such as biosensing, water purification and catalysis. This journal is © the Partner Organisations 2014.

DOI： 10.1039/c4ra00873a

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Pore architecture of catalyst supports is an important factor facilitating accessibility of reactants to catalytic sites. This holds the key to improving catalytic activities. Amongst various catalytic reactions, supported Pd nanoparticles-catalyzed C-C cross-coupling reactions have been attracting a great deal of attention in the last decade. Although various supports have been examined, applications of hierarchically porous monolithic materials have never been reported, mainly because of difficulties in multistep synthesis of catalysts. We herein report a novel on-site reduction-based methodology using hierarchically porous hydrogen silsesquioxane (HSQ) monoliths for one-step synthesis of Pd nanoparticles-embedded monoliths (Pd@HSQ). Characterization of these monoliths evidences the on-site reduction, i.e. formation of Pd nanoparticles and conversion of Si-H present in the monolith to Si-O∼. Fast, quantitative reduction of Pd2+ to Pd(0) to form supported Pd nanoparticles is achieved with preservation of the porous structure of the original monolith, which makes this material attractive as a catalyst for C-C cross-coupling reactions. The obtained Pd@HSQ catalyst has been employed in the Mizoroki-Heck cross-coupling reaction. High accessibility of reactant molecules, undetectable leaching of Pd nanoparticles and easy separation of the monolith from liquid media provide high catalytic activity, reusability and easy handling. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

DOI： 10.1039/c3nj01433a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

In this research, we have successfully prepared hierarchically porous chromium-based non-oxide ceramic monoliths (chromium nitride (CrN) and chromium carbide (Cr3C2)) by facile two-step methods. By utilizing an epoxide-mediated sol-gel reaction accompanied by phase separation, a well-defined macroporous structure is tailored in the chromium (oxy)hydroxide-urea composites in the presence of poly(acrylic acid). Urea works as a nitrogen and/or carbon source through the following heat-treatment, whereas poly(acrylic acid) behaves as a phase separation inducer as well as a network-supporting constituent. The macroporous morphology of xerogels is controllable by changing the starting composition. Heat-treatment for thus obtained xerogels under an air atmosphere provides chromium oxide (Cr 2O3), whereas that under a nitrogen atmosphere leads to the crystallization of CrN at 700 °C and Cr3C2 at 900 °C without any deterioration of the porous morphologies. The heat-treated samples possess a high specific surface area up to 450 m2 g -1 as well as high porosity over 80%, preserving good mechanical strength. This facile and novel synthesis strategy has a potential extendability to other macroporous monoliths with high surface area based on various metal nitrides and carbides, which are useful in various applications such as catalysts, semiconductor devices, magnetic materials, and refractory materials. © 2014 The Royal Society of Chemistry.

DOI： 10.1039/c3ta13725b

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

Supported metal alloy nanoparticles demonstrate high potential in designing heterogeneous catalysts for organic syntheses, pollution control and fuel cells. However, requirements of high temperature and multistep processes remain standing problems in traditional synthetic strategies. We herein present a low-temperature, single-step, liquid-phase methodology for designing monolith-supported metal alloy nanoparticles with high physicochemical stability and accessibility. Metal ions in aqueous solutions are reduced to form their corresponding metal alloy nanoparticles within hierarchically porous hydrogen silsesquioxane (HSQ, HSiO1.5) monoliths bearing well-defined macro- and mesopores and exhibiting high surface redox activity due to the presence of abundant Si-H groups. Supported bi-, tri- and tetrametallic nanoparticles have been synthesized with controlled compositions and loadings, and characterized in detail by microscopy and spectroscopy techniques. Examination of these supported metal alloy nanoparticles in catalytic reduction of 4-nitrophenol shows high catalytic activities depending on their compositions. Their recyclability and potential application in continuous flow reactors are also demonstrated. This journal is © the Partner Organisations 2014.

DOI： 10.1039/c4ta01767f

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：New Journal of Chemistry  

Hierarchically porous N-doped TiO2 materials have been synthesized from macroporous inorganic-organic hybrid gels composed of titanium bridged with ethylenediamine. Homogeneously dispersed nitrogen in the precursor gel networks leads to TiO2 doped with a large amount of nitrogen, which delivers high discharge capacity and good cycle performance as a negative electrode for Li-ion batteries. © 2014 The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

DOI： 10.1039/c3nj01332d

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Porous Materials  

Macroporous methylsilsesquioxane (MSQ) monoliths have been prepared by in situ two-step processing using an initial acid catalysis step accompanied by an epoxide-mediated condensation step in the presence of ammonium chloride (NH 4Cl). We investigate the effects of duration time of acidic step, heat-treatment and hydrothermal treatment on the macroporous morphology and pore structures of MSQ monoliths. The duration time of acidic step gives an important effect on the macroporous morphology and pore structures of MSQ monoliths, resulting from the polymerization of MSQ. Heat-treatment and hydrothermal treatment basically do not spoil the macroporous morphology of MSQ monoliths, while obviously varies the mesopore/micropore structures including pore size, pore volume, and pore size distribution. The macroporous MSQ materials with thick skeleton and intrinsic hydrophobicity are promising for wide applications such as ultra performance liquid chromatography (UPLC), superhydrophobic materials and so on. © 2013 Springer Science+Business Media New York.

DOI： 10.1007/s10934-013-9733-z

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Langmuir  

Synthesis of class II hybrid silica materials requires the formation of covalent linkage between organic moieties and inorganic frameworks. The requirement that organosilylating agents be present to provide the organic part limits the synthesis of functional inorganic oxides, however, due to the water sensitivity and challenges concerning purification of the silylating agents. Synthesis of hybrid materials with stable molecules such as simple alcohols, rather than with these difficult silylating agents, may therefore provide a path to unprecedented functionality. Herein, we report the novel functionalization of silica with organic alcohols for the first time. Instead of using hydrolyzable organosilylating agents, we used stable organic alcohols with a Zn(II) catalyst to modify the surface of a recently discovered highly reactive macro-mesoporous hydrogen silsesquioxane (HSQ, HSiO1.5) monolith, which was then treated with water with the catalyst to form surface- functionalized silica. These materials were comprehensively characterized with FT-IR, Raman, solid-state NMR, fluorescence spectroscopy, thermal analysis, elemental analysis, scanning electron microscopy, and nitrogen adsorption-desorption measurements. The results obtained from these measurements reveal facile immobilization of organic moieties by dehydrogenative addition onto surface silane (Si-H) at room temperature with high loading and good tolerance of functional groups. The organic moieties can also be retrieved from the monoliths for recycling and reuse, which enables cost-effective and ecological use of the introduced catalytic/reactive surface functionality. Preservation of the reactivity of as-immobilized organic alcohols has been confirmed, moreover, by successfully performing copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reactions on the immobilized silica surfaces. © 2013 American Chemical Society.

DOI： 10.1021/la402205j

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

In this report, we demonstrate a novel synthesis method to obtain reduced titanium oxides with monolithic shape and with a well-defined hierarchically porous structure from the titanium-based network bridged with ethylenediamine. The hierarchically porous monoliths are fabricated by the nonhydrolytic sol-gel reaction accompanied by phase separation. This method allows a low-temperature crystallization into Ti4O7 and Ti3O5 at 800 and 900 C, respectively, with N-doped carbon. These reduced titanium oxides are well-doped with N atoms even under argon atmosphere without NH 3, which accounts for the low-temperature reduction. The resultant monolithic materials possess controllable macropores and high specific surface area together with excellent electric conductivity up to 230 S cm-1, indicating promise as a conductive substrate that can substitute carbon electrodes. © 2013 American Chemical Society.

DOI： 10.1021/cm401933a

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Macromolecules  

An organotellurium chain transfer agent (CTA) bearing a triethoxysilyl group at one end and a 2-methyltellanyl-2-methylpropionate group at the other was prepared and immobilized on the surface of a silicon wafer and silica nanoparticle (SiP). Surface-initiated organotellurium-mediated living radical polymerization (SI-TERP) from the immobilized CTA in the presence of nonimmobilized (free) organotellurium CTA was examined. Concentrated polymer brushes (CPBs) having surface occupancies above 0.1 were prepared by polymerization of various monomers, including styrene, methyl methacrylate, butyl acrylate, N-isopropyl acrylamide, N-vinyl pyrrolidone (NVP), and N-vinyl carbazole (NVC). All CPBs were formed in a controlled manner, with number-average molecular weights close to the theoretical values and low polydispersity indices (<1.41). Structurally well-controlled CPBs comprising unconjugated monomers, NVP and NVC, were prepared for the first time. Atomic force microscopy and transmission electron microscopy analyses of the CPBs revealed the highly stretched and anisotropic structure of the grafted polymer chain in a good solvent. © 2013 American Chemical Society.

DOI： 10.1021/ma401385a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the European Ceramic Society  

Mullite monoliths with well-defined macropores and mesostructured skeletons have been prepared via the sol-gel process accompanied by phase separation in the presence of poly(ethylene oxide) (PEO). Gelation of Al2O3-SiO2 binary system with chloride salts as an additional precursor has been mediated by propylene oxide (PO) as an acid scavenger, while PEO worked as a phase-separation inducer. The dried gel and that heat-treated at 800°C are amorphous, and γ-Al2O3 or Si-Al spinel phase nanocrystals are crystallized at 900-1000°C. After heat-treated at and above 1100°C for 5h, the complete crystalline mullite is generated, and the macroporous monoliths in large dimensions of more than 15mm×15mm×10mm are obtained. Heat-treatment at 200-1400°C does not basically spoil the macroporous structure of monoliths, while decreases the macropore size and significantly alters the phase compositions and micro-mesoporous structure. © 2013 Elsevier Ltd.

DOI： 10.1016/j.jeurceramsoc.2013.02.018

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Monolithic macroporous titanium dioxide (TiO2) derived from ionic precursors has been successfully prepared via the sol-gel route accompanied by phase separation in the presence of formamide (FA) and poly(vinylpyrrolidone) (PVP). The addition of FA promotes the gelation, whereas PVP enhances the polymerization-induced phase separation. Appropriate choice of the starting compositions allows the production of cocontinuous macroporous TiO2 monoliths in large dimensions, and controls the size of macropores. The resultant dried gel is amorphous, whereas anatase and rutile phases are precipitated at 500 and 900 C respectively, without spoiling the macroporous morphology. Nitrogen adsorption-desorption measurements revealed that the dried gels exhibits mesostructure with a median pore size of about 3 nm and BET surface area of 228 m2/g, whereas 15 nm and 73 m 2/g for the gels calcined at 600 C. © 2013 Springer Science+Business Media New York.

DOI： 10.1007/s10971-013-3123-5

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10971-013-3094-6

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

Utilizing a facile sol-gel reaction accompanied by phase separation, rigid monolithic nickel hydroxide-based xerogels and nickel/carbon composites with hierarchical porosity have been successfully fabricated. In the synthetic route starting from nickel chloride as a nickel precursor, trimethylene oxide acts as a gelation initiator to increase pH in a reaction solution. In addition, poly(acrylic acid) plays a double role as a phase separation inducer and as a co-constituent with nickel hydroxide to comprise continuous gel skeletons in the micrometer range. As a result, obtained xerogels possess well-defined macropores evidenced by microscopy observation and mercury porosimetry. Subsequent heat-treatment in air led to the crystallization of NiO at 300 C, while calcination under argon flow brought about the formation of nickel/carbon (Ni/C) composites with hierarchical pores and large specific surface area at temperatures higher than 300 C. This is the first report on the preparation of rigid monolithic xerogels and metal/carbon composite with well-defined macropores based on a metal salt precursor containing "divalent" cation. © 2013 Elsevier B.V.All rights reserved.

DOI： 10.1016/j.micromeso.2013.03.042

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Science and Technology of Advanced Materials  

Monolithic aluminum phosphate (AlPO4) with a macro-mesoporous structure has been successfully prepared via the sol-gel process accompanied by phase separation in the presence of poly(ethylene oxide) (PEO). Gelation of the system has been mediated by propylene oxide (PO), while PEO induces a phase separation. The dried gel is amorphous, whereas the crystalline tridymite phase precipitates upon heating above 1000 °C. Heat treatment does not spoil the macroporous morphology of the AlPO4 monoliths. Nitrogen adsorption-desorption measurements revealed that the skeletons of the dried gels possess a mesostructure with a median pore size of about 30 nm and a surface area as high as 120 m2 g-1. Hydrothermal treatment before heat treatment can increase the surface area to 282 m2 g -1. © 2013 National Institute for Materials Science.

DOI： 10.1088/1468-6996/14/4/045007

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Advanced Functional Materials  

A facile synthesis of a new class of reactive porous materials is reported: hierarchically porous hydrogen silsesquioxane (HSiO1.5, HSQ) monoliths with well-defined macropores and mesopores. The HSQ monoliths are prepared via sol-gel accompanied by phase separation in a mild condition, and contain micrometer-sized co-continuous macropores and high specific surface area reaching up to 800 m2 g-1 because of the small mesopores. A total preservation of Si-H, which is always an issue of HSQ materials, is confirmed by 29Si solid-state NMR. The HSQ monolith has then been subjected to reduction of noble metal ions to their corresponding metal nanoparticles in simple aqueous solutions under an ambient condition. The nanoparticles produced in this manner are immobilized on the HSQ monolith and are characterized by X-ray diffraction (XRD) and high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Both the bare HSQ and nanoparticles-embedded HSQ are promising as heterogeneous catalysts, exhibiting reusability and recyclability. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/adfm.201202558

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Separation Science  

Reproducible fabrication of the hierarchically porous monolithic silica in a large volume exceeding 1000 mL has been established. By the hydrothermal enlargement of the fully accessible small pores to exceed 50 nm in diameter, the capillary force emerged on solvent evaporation was dramatically reduced, which allowed the preparation of crack-free monoliths with evaporative solvent removal under an ambient pressure. The local temperature inhomogeneity within a reaction vessel in a large volume was precisely controlled to cancel the heat evolved by the hydrolysis reaction of tetramethoxysilane and that consumed to melt ice cubes dispersed in the solution, resulting in large monolithic silica pieces with improved structural homogeneity. Homogeneity of the pore structure was confirmed, both on macro- and mesoscales, using SEM, mercury intrusion, and nitrogen adsorption/desorption measurements. Furthermore, the deviations in chromatographic performance were examined by evaluating multiple smaller monolithic columns prepared from the monolithic silica pieces cut from different parts of a large monolith. All the daughter columns thus prepared exhibited comparable performances to each other to prove the overall homogeneity of the mother monolith. Preliminary results on high-speed separation of peptides and proteins by the octadecylsilylated silica monolith of the above production have also been demonstrated. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOI： 10.1002/jssc.201300123

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Silver nanoparticles (Ag NPs) have been homogeneously introduced into hierarchically porous monolithic silica columns with well-defined macropores and SBA-15-type hexagonally ordered mesopores by using ethanol as the mild reductant. Within the cylindrical silica mesopores treated with aminopropyl groups as the host, monocrystalline Ag NPs and nanorods are obtained after being treated in silver nitrate/ethanol solution at room temperature for different durations of reducing time. The loading of Ag NPs in the monolith can be increased to 33 wt % by the repetitive treatment, which also led to the formation of polycrystalline Ag nanorods in the mesopores. Although the bare silica column cannot separate aromatic hydrocarbons, good separation of those molecules by noncharged Ag NPs confined in the porous structure of the monolith has been for the first time demonstrated with the Ag NP-embedded silica column. The NP-embedded monolithic silica would be a powerful separation tool for hydrocarbons with different number, position, and configuration of unsaturated bonds. © 2013 American Chemical Society.

DOI： 10.1021/am303163s

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica  

Macroporous SiO2 monoliths were prepared via a sol-gel process accompanied by phase separation using a tetramethoxysilane (TMOS) precursor, 0.01 mol·L-1 HCl catalyst, propylene oxide (PO) gelation agent, and poly(ethylene oxide) (PEO, viscosity-averaged molecular weight (Mv): 10000) phase separation inducer. Monoliths were characterized by differential thermal analysis/thermogravimetry (DTA/ TG), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), mercury porosimetry, and nitrogen adsorption/desorption analysis (BET). The mechanism of the epoxide-mediated sol-gel reaction and PEO induced phase separation was discussed. The addition of PEO induced phase separation, and monolithic SiO2 with a cocontinuous macroporous skeletal structure was obtained at PEO/TMOS molar ratio of 0.0018. Monoliths had a narrow pore size distribution of 1-3 μm, surface area as high as 719 m2·g-1 and pore volume of 0.48 m3·g-1. This sol-gel transition is mediated by PO because of its strong nucleophilic properties and irreversible ring-opening reaction. Simultaneous phase separation is induced by PEO adsorbed on the SiO2 oligomers. © Editorial office of Acta Physico-Chimica Sinica.

DOI： 10.3866/PKU.WHXB201212252

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Physical Chemistry Chemical Physics  

Monolithic Li2FeSiO4-carbon composites with well-defined macropores have been prepared from the silica-based gels containing Li, Fe, and carbon sources. The macroporous precursor gels can be fabricated by the sol-gel method accompanied by phase separation. A fine control of the macropore size in the resultant composites has been achieved by controlling the macropore size of the precursor gels simply by adjusting the starting compositions. The effects of pore properties on Li insertion-extraction capabilities have been investigated by utilizing the resultant Li 2FeSiO4-carbon composites as the cathode of lithium ion batteries. The electrodes prepared from the Li2FeSiO 4-carbon composites with different macropore sizes exhibit significant differences in the charge-discharge properties. The results strongly suggest that the smaller macropore size (equal to the thinner macropore skeletons) and the presence of micro- and mesopores in the macropore skeletons (hierarchically porous structure) are desirable for a better electrode in the case of Li2FeSiO4, which has extremely low ionic and electrical conductivities. © 2013 The Owner Societies.

DOI： 10.1039/c3cp50352f

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

Starting from an aqueous solution, porous zinc ferrite-based xerogel monoliths have been prepared via a sol-gel route accompanied by phase separation mediated by propylene oxide in the presence of poly(acrylamide). The xerogels possess well-defined macropores, and the macroporous morphologies could be easily controlled (macropore size ranges from 0.55 to 1.29 μm) by simply changing the starting composition. As-dried xerogel samples were amorphous under X-ray diffraction, while heat-treatment in air brought about the formation of spinel type ferrite phase, ZnFe<inf>2</inf>O<inf>4</inf>. Calcination under Ar atmosphere allowed the crystallization of various iron-based phases/carbon composites (Fe<inf>3</inf>O<inf>4</inf>, Fe<inf>1-δ</inf>O, Fe <inf>3</inf>N, Fe<inf>4</inf>N, Fe<inf>3</inf>C, and Fe). Samples heated under Ar flow exhibited hierarchical pore structures, including continuous macropores, in addition to mesopores and micropores embedded in the carbon-containing composite matrices. © 2013 The Royal Society of Chemistry.

DOI： 10.1039/c3ra22481c

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1039/c3ra90142d

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ROYAL SOC CHEMISTRY  

DOI： 10.1039/c3ra90142d

Web of Science

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry A  

Monolithic layered double hydroxides (LDHs) with interconnected channels have been expected to enhance sorption rate as well as increase accumulation of anions. Although powder molding can form easily-handled LDH compacts, interconnected channel formation therein has not been achieved. Herein, we demonstrate cm-scale monolithic LDH-based composites with interconnected hierarchical channels via a spontaneous sol-gel reaction. The synthesis was performed on Mg-Al hydrotalcite-type LDHs starting from metal chlorides aqueous/ethanolic solution with poly(ethylene oxide) incorporated. Addition of propylene oxide triggers a sol-gel reaction to form monolithic xerogels with a formula of [Mg0.66Al0.33(OH)2Cl 0.33·2.92H2O]·3.1Al(OH)3. LDH crystals together with aluminum hydroxide crystals homogeneously build up gel skeletons with well-defined hierarchical channels. The interconnected channel in μm range (macrochannel) are formed as a phase-separated structure, whereas the channel in nm range (nanochannel) are as interstices of primary particles. The channel architectures are preserved in the course of rehydration process, affording enhanced sorption affinity for anion species in the process. Both of macro and mesochannels as well as high charge density of the obtained LDHs (Mg/Al = 2.0) contribute to enhanced anion sorption in the monolithic xerogels. The materials obtained here opens up applications of high performance adsorbents and ion-storage free from diffusion limitation. © 2013 The Royal Society of Chemistry.

DOI： 10.1039/c3ta11110e

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

We report an electrically conducting oxygen-deficient anatase TiO 2-x monolith with macro/meso/micro trimodal pores, prepared by reducing insulating porous TiO2 monoliths at low temperature. Without adding any conductive materials, the TiO2-x monolith itself was electrically conducting enough for lithium insertion, potentially opening a new avenue for carbon-free electrode materials. © The Royal Society of Chemistry 2013.

DOI： 10.1039/c3ra40545a

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Physical Chemistry C  

The effects of the pore properties and the ionic sizes on the electric double-layer capacitances have been investigated by using the monolithic carbon electrodes with different pore properties. The carbon monoliths with high surface areas which possess homogeneous pore properties in the whole monoliths were prepared from the bridged-polysilsesquioxane gels via the nanophase extraction technique. The detailed investigations of the pore properties of the carbon monoliths were conducted by the nitrogen physisorption measurement as well as the mercury porosimetry. The electrochemical property of each monolithic carbon electrode was examined by the cyclic voltammetry in the different aqueous electrolytes in order to investigate the effects of the ionic sizes. These fundamental analyses have provided new insights into the efficient micropore sizes in each electrolyte for the superior electric double-layer capacitors. © 2012 American Chemical Society.

DOI： 10.1021/jp309010p

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

Structure and physical properties of monolithic polymethylsilsesquioxane (PMSQ, CH 3SiO 1.5) aerogels have been systematically examined with varied starting compositions using a sol-gel system containing surfactant n-hexadecyltrimethylammonium chloride (CTAC). The precursor methyltrimethoxysilane (MTMS) undergoes hydrolysis and polycondensation under an acid-base two-step reaction to obtain uniform gels as a one-pot reaction. To compare the samples, each factor of starting composition, such as amount of CTAC, concentration of aqueous acetic acid solution, volume of solvent and amount of urea, is independently varied. With appropriate concentrations of surfactant CTAC, the aerogels with high light transmittance (at 550 nm) are obtained, owing to the effective suppression of macroscopic phase separation. Acid-base catalysts, acetic acid and urea also impose significant effects on the properties of obtained aerogels including their molecular-level structures. The aerogel with 91% of light transmittance was obtained under an optimized condition. The lowest density of the PMSQ aerogel in this system reaches 0.045 g cm -3. © 2012 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.micromeso.2012.03.049

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Various iron-based polycrystalline monoliths, Fe 3O 4, iron, and Fe 3C, with hierarchically distributed pores have been synthesized from ionic precursors using a sol-gel process accompanied by phase separation. Propylene oxide acts as a proton scavenger to increase pH moderately and uniformly in a reaction solution, which leads to homogeneous gelation. On the other hand, poly(acrylamide) works as a phase separation inducer as well as a precipitation inhibitor. Appropriate choice of iron precursor, solvent, polymer, and epoxide allowed the formation of iron(III)-based xerogels with cocontinuous macroporous structures. The dried gels were amorphous, whereas heating in air above 300 °C led to the formation of α-Fe 2O 3. Calcination under an inert condition above 400 °C formed Fe 3O 4, iron, and Fe 3C without collapse of macrostructures. Examination has been carried out using SEM, TG-DTA, FT-IR, Hg intrusion, pH measurement, X-ray diffraction, and N 2 adsorption-desorption. © 2012 American Chemical Society.

DOI： 10.1021/cm300495j

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Materials Letters  

In this report, we demonstrate the facile preparation of macroporous monolithic materials based on graphitized carbon by utilizing catalytic graphitization at relatively low temperature (1000°C). The precursor polymer, macroporous resorcinol-formaldehyde (RF) xerogel, can be obtained without any surfactants or polymeric additives in water/ethanol mixed solvent via the sol-gel reaction accompanied by phase separation. The use of iron chloride as an acid catalyst for polymerization provides the RF monoliths incorporated with Fe, which catalyzes the graphitization. The effects of the starting composition on the morphologies of the resultant RF gels and the characteristics of the graphitized carbon monoliths have been discussed. © 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.matlet.2012.02.069

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

Hierarchically porous carbon monoliths with high specific surface area have been prepared via a nano-phase extraction technique from carbon/silica composites which had been prepared from arylene-bridged polysilsesquioxanes. The nano-sized silica phase developed in the composite has been removed to increase micropores, resulting in a similar effect to thermal activation of carbons. The resultant carbons are expected to possess homogeneously distributed micropores. Here we report the changes of the pore characteristics through the synthesis process by the nitrogen adsorption-desorption method and mercury porosimetry. In particular, the growth of silica phase in carbon/silica composites at different temperatures has been characterized by the micropore analysis using the Horváth-Kawazoe method. © 2011 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.micromeso.2012.02.001

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

Organosiloxane (RnSiO(4-n)/2) gels can be prepared from organoalkoxysilanes using the sol-gel process. In general,however, formation of uniform networks from these precursors is strongly inhibited due to cyclization reactions. In addition, phase separation of hydrophobic condensates from polar solvent leads to inhomogeneous gels in these systems. A careful control of the hydrolysis and polycondensation reactions is therefore required to obtain a monolithic gel with desired properties. We have been trying to control the sol-gel reactions as well as phase separation in these systems to obtain unique porous materials particularly from methyltrimethoxysilane(MTMS) and dimethyldimethoxysilane (DMDMS). Flexible aerogels and xerogels based on the methylsiloxane networks are discussed.

DOI： 10.2497/jjspm.59.320

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Colloid and Interface Science  

Surface modification of titania materials to give flower-like structures has been achieved simply by the treatment in lithium hydroxide aqueous solution under mild conditions. The flower-like structured materials were characterized by X-ray diffraction, thermogravimetric analysis, and Raman scattering. The analyses indicate that the flower-like materials are composed of layered hydrous lithium titanate. It is suggested that the unique intercalation behavior of lithium ions into titania allows dissolution and re-precipitation of titania to form the flower-like structure. The obtained flower-like structure can be retained up to 700°C, while the crystal phase transforms into Li 4Ti 5O 12. © 2012 Elsevier Inc.

DOI： 10.1016/j.jcis.2012.02.002

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：ACS Applied Materials and Interfaces  

Macroporous polymer monoliths based on poly(styrene-co-divinylbenzene) with varied styrene/divinylbenzene ratios have been prepared by organotellurium- mediated living radical polymerization. The well-defined cocontinuous macroporous structure can be obtained by polymerization-induced spinodal decomposition, and the pore structures are controlled by adjusting the starting composition. The separation efficiency of small molecules (alkylbenzenes) in the obtained monoliths has been evaluated in the capillary format by high-performance liquid chromatography (HPLC) under the isocratic reversed-phase mode. Baseline separations of these molecules with a low pressure drop (∼2 MPa) have been achieved because of the well-defined macropores and to the less-heterogeneous cross-linked networks. © 2012 American Chemical Society.

DOI： 10.1021/am300552q

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

エアロゲルの力学的強度を改善するため、非反応性のメチル基により柔軟性や低い架橋密度を実現した有機-無機ハイブリッドエアロゲルがこれまでに研究されてきた。本研究においては3官能性ケイ素アルコキシドmethyltrimethoxysilane (MTMS) と2官能性アルコキシドdimethyldimethoxysilane (DMDMS) を前駆体、<I>n</I>-hexadecyltrimethylammonium chloride (CTAC) を相分離抑制のための界面活性剤として用い、酢酸と尿素を使った酸性/塩基性触媒による2段階ゾル－ゲル反応でエアロゲルを合成することに成功している。この出発組成を変化させることでエアロゲルの微細構造や結合を制御し、密度・力学特性の変化を調べた。

DOI： 10.14853/pcersj.2012S.0.280.0

記述言語：英語   掲載種別：研究論文（学術雑誌）  

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：International Journal of Polymer Science  

By combining the micellar templating in nanometer scale with the polymerization-induced phase separation in micrometer scale, ethylene-bridged polysilsesquioxane gels with hierarchical macropores and mesopores are prepared. The difference of mesopore structures depending on the method of the solvent removal has been observed by the X-ray diffraction and the nitrogen adsorption-desorption measurements. During the hydrothermal treatment under the basic condition, the reorganization of the polysilsesquioxane gel network occurred differently depending on the alkoxy group contained in the precursors. From 29Si CP/MAS NMR measurements, it was revealed that the crosslinking density of the hydrothermally treated gels was increased so that the highly ordered mesostructure of the wet gel could be preserved even after the evaporative drying of solvent. © 2012 Atsushi Mushiake et al.

DOI： 10.1155/2012/460835

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1007/s10971-012-2790-y

researchmap

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：公益社団法人 日本セラミックス協会  

細孔特性の精密な制御が可能な相分離法によって，細孔サイズが一様で，連続したマクロ孔をもつシリカやアルミナ，チタニアなどのマクロ多孔性酸化物モノリス体が得られているが、従来の報告は全て絶縁体であった．我々は相分離法により得られたTiO<SUB>2</SUB>のマクロ多孔性モノリス体に対して，金属ジルコニウムを用いた還元反応を行い，一連の酸素欠損型チタン酸化物Ti<SUB><I>n</I></SUB>O<SUB>2<I>n</I>－1</SUB> (<I>n</I> = 2, 3, 4, 6)のマクロ多孔性モノリス体をそれぞれ単相で作製した．得られた一連の還元体はTiO<SUB>2</SUB>前駆体の孔特性をほぼ完全に維持している．また従来の約半分のバルク密度(1.8 g cm<SUP>－3</SUP>)，約3倍の空孔率(60%)，そして同等の室温バルク抵抗率(2 × 10<SUP>－2</SUP> Ω cm)を有しており，様々な電極材料としての応用が考えられる．

DOI： 10.14853/pcersj.2012S.0.526.0

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：RSC Advances  

Transparent and low-density methylsilsesquioxane (MSQ, CH 3SiO 1.5) aerogels can be obtained solely from methyltrimethoxysilane (MTMS) by a one-pot two-step process under the co-presence of surfactant. In the present study, we have systematically investigated the effects of the molecular structure of triblock copolymer-type nonionic surfactants PEO-b-PPO-b-PEO (PEO and PPO denote poly(ethylene oxide) and poly(propylene oxide) units, respectively) on the properties of the resultant MSQ aerogels. Macroscopic phase separation of hydrophobic MSQ networks from polar solvent occurs when no surfactant is employed, which results in macroporous opaque aerogels. In contrast, a co-presence of appropriate surfactant effectively suppresses the phase separation and yields transparent aerogels after supercritical drying. By employing various surfactants having different molecular weight and PO/EO ratio, the mechanism of suppression of phase separation or pore formation is discussed in detail. In situ 1H NMR suggests that the PO units of surfactant interact with the hydrophobic MSQ network enriched with methyl groups and make the MSQ network hydrophilic by extending EO chains toward the aqueous solvent in the late phase of gelation, until which hydrogen bonding dominates between the Si-OH groups of polymerizing MSQ and the ether oxygens of the EO unit. Through the comprehensive understanding of the role of surfactant, the strategy for rational design of MSQ aerogels materials has become developable. © 2012 The Royal Society of Chemistry.

DOI： 10.1039/c2ra20799k

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

A novel and facile method for the preparation of monolithic LiFePO 4/carbon composites with well-defined macropores has been developed. The precursor macroporous gels consisting of inorganic networks as well as organic polymers were fabricated by the epoxide-mediated sol-gel method accompanied by phase separation. The inorganic-organic hybrid gels were calcined under an inert atmosphere, resulting in LiFePO4/carbon monoliths. The influence of the starting compositions on the gel morphologies has been investigated, and the constituents of the gel network were discussed. The reaction mechanism of the crystallization of LiFePO4 from green bodies during calcination has also been investigated by thermal analysis, X-ray diffraction, and Raman scattering. In addition, the electrochemical properties of the resultant LiFePO4/carbon composites were examined by the charge-discharge test. © 2011 American Chemical Society.

DOI： 10.1021/cm2021438

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Materials Research Society Symposium Proceedings  

Macro/meso/microporous carbon monoliths doped with sulfur have been prepared from sulfonated polydivinylbenzene networks followed by the activation with CO 2 resulted in the activated carbon monoliths with high surface area of 2400 m 2 g -1. The monolithic electrode of the activated carbon shows remarkably high specific capacitance (175 F g -1 at 5 mV s -1 and 206 F g -1 at 0.5 A g -1). © 2011 Materials Research Society.

DOI： 10.1557/opl.2011.604

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Materials Research Society Symposium Proceedings  

Recent years, although silica aerogels are expected to be the promising material for energy savings, the lack of mechanical strength prevents from commercial applications such as to low-density thermal insulators. To improve mechanical properties, methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) are used in this study as the co-precursor of aerogels because the network becomes flexible due to the relatively low cross-linking density and to the unreacted methyl groups. Because of the strong hydrophobicity of MTMS/DMDMS-derived condensates, phase separation occurs in aqueous sol and must be suppressed to obtain uniform and monolithic gel. We employed surfactant n-hexadecyltrimethylammonium chloride (CTAC) in starting compositions to control phase separation during a 2-step acid/base sol-gel reaction. By changing the starting composition, various microstructures of pores are obtained. In the uniaxial compression test, the aerogel showed high flexibility and spring-back to the original shape after removing the stress. © 2011 Materials Research Society.

DOI： 10.1557/opl.2011.216

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Materials Research Society Symposium Proceedings  

A transition of porous structures in monolithic poly(methylsilsesquioxane) (PMSQ, CH 3SiO 1.5) gels from uniform mesopores to hierarchical pore structures consisting of macro- and mesopores, has been investigated using a sol-gel system containing surfactant Pluronic F127. A broad variation of porous morphology is controlled by changing the concentration of F127. Sufficient concentrations of F127 inhibit the occurrence of macroscopic phase separation of hydrophobic PMSQ condensates and lead to well-defined mesoporous transparent aerogels with high specific pore volume. Mesopores are developed through microscopic phase separation of PMSQ colloid-surfactant complexes in the solvent. Macroscopic phase separation regulates well-defined macropores in the micrometer range on decreasing concentrations of F127, in which microscopic phase separation concurrently takes place in the PMSQ-rich gelling phase after the onset of macroscopic phase separation. Monolithic PMSQ gels with hierarchical macro- and mesopore structures are consequently obtained. © 2011 Materials Research Society.

DOI： 10.1557/opl.2011.96

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Wiley-VCH  

DOI： 10.1002/9783527639588.ch8

Scopus

researchmap

記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Wiley-VCH  

DOI： 10.1002/9783527639588.ch17

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Separation Science  

Separation media based on hierarchically porous titania (TiO2) monoliths for highperformance liquid chromatography (HPLC) have been successfully fabricated by the sol-gel process of titanium alkoxide in a mild condition utilizing a chelating agent and mineral salt. The as-gelled TiO 2 monoliths were subjected to a simple solvent exchange process from ethanol (EtOH) to H2O followed by drying and calcination. The resultant monolithic TiO2 columns consist of anatase crystallites with the typical specific surface area of more than 200m2/g. The resultant monolithic TiO2 column calcined at 200 and 400°C exhibited a good separation performance for organophosphates as well as for polar benzene derivatives in the normal-phase mode. © 2011 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim.

DOI： 10.1002/jssc.201100538

Web of Science

Scopus

PubMed

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the American Ceramic Society  

Hierarchically porous nanocrystalline CaTiO3, SrTiO 3, and BaTiO3 ceramics have been produced by impregnating corresponding alkaline-earth metal ions into preformed macroporous TiO2 monoliths in a solution containing urea, followed by calcination. The macroporous TiO2 had been obtained via the sol-gel process accompanied by phase separation utilizing a chelating agent, ethyl acetylacetonate (EtAcAc), together with mineral salt and ammonium chloride, to decrease the reactivity of titanium alkoxide. Formations of CaCO3, SrCO3, and BaCO3 on the surface of TiO2 monoliths are promoted by CO2 generated by the concurrent two processes during impregnation; hydrolysis, and decarbonation of the chelating agent EtAcAc, and hydrolysis of urea at 60°C. The latter also raises pH of the impregnating solution which further promotes the mineralization of the carbonate salts. Calcination of the resultant monolithic composite of metal carbonate/TiO2 allows the crystallization of metal titanate. The addition of urea to the impregnating solution is found to be an effective strategy for the formation of perovskite monoliths by the impregnation process. This study provides a versatile approach to the preparation of hierarchically porous titania-based perovskites. © 2011 The American Ceramic Society.

DOI： 10.1111/j.1551-2916.2011.04613.x

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Polymer  

Rigid methacrylate-based polymer monoliths with well-defined macropores have been synthesized from glycerol 1,3-dimethacrylate (GDMA) and trimethylolpropane trimethacrylate (Trim) by organotellurium-mediated living radical polymerization. In each system, poly(ethylene oxide) induced spinodal decomposition with the progress of polymerization of GDMA or Trim. Well-defined macroporous structure can be tailored by fixing the bicontinuous structure by the sol-gel transition. Both polymer monoliths possessed macropores with narrow size distributions and the macropore size can be controlled simply by varying the amount of poly(ethylene oxide). Starting from GDMA, polymer monoliths with unimodal macropores can be obtained due to the collapse of micro- and mesopores, which were originally embedded in macropore skeletons, by large shrinkage during drying. In contrast, starting from Trim, the obtained polymer monoliths include not only macropores but also micro- and mesopores, which lead to high specific surface area (470 m2 g-1), owing to the higher crosslinking density. © 2011 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.polymer.2011.08.028

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of the Ceramic Society of Japan  

In this study, we for the first time came up with a facile approach to fabricate hierarchically porous nano-crystalline monolithic magnesium titanates (MgTi2O5/MgTiO3) by impregnating magnesium chloride into hierarchically porous TiO2 monolith in a solution containing urea followed by appropriate heat-treatment. The formation of porous MgTi2O5/MgTiO3 monolithic materials took place by the solid-state reaction between original TiO2 networks and precipitated MgCO3. The MgCO3 is precipitated within the TiO2 wet gel by the reaction between impregnated Mg2+ and CO2, which is produced by hydrolysis and decarbonation of chelating agent in the TiO2 wet gels and by the hydrolysis of urea at 60°C. The resultant porous magnesium titanates retained narrow macropore size distribution centered at the diameter ̃1 μm. These porous monoliths produced by impregnation, a facile and the low-cost method, are expected to open various engineering applications owing to the low thermal expansion coefficients and high chemical and physical stabilities. © 2011 The Ceramic Society of Japan.

DOI： 10.2109/jcersj2.119.440

Web of Science

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

A systematic study is reported on the performance of long monolithic capillary columns in gradient mode. Using a commercial nano-LC system, reversed-phase peptide separations obtained through UV-detection were conducted. The chromatographic performance, in terms of conditional peak capacity and peak productivity, was investigated for different gradient times (varying between 90 and 1320min) and different column lengths (0.25, 1, 2 and 4m) all originating from a single 4m long column. Peak capacities reaching values up to n=103 were measured in case of the 4m long column demonstrating the high potential of these long monoliths for the analysis of complex biological mixtures, amongst others. In addition, it was found that the different column fragments displayed similar flow resistance as well as consistent chromatographic performance in accordance with chromatographic theory indicating that the chromatographic bed of the original 4m long column possessed a structural homogeneity over its entire length. © 2010 Elsevier B.V.

DOI： 10.1016/j.chroma.2010.10.045

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Colloid and Interface Science  

A transition from hierarchical pore structures (macro- and meso-pores) to uniform mesopores in monolithic polymethylsilsesquioxane (PMSQ, CH3SiO1.5) gels has been investigated using a sol-gel system containing surfactant Pluronic F127. The precursor methyltrimethoxysilane (MTMS) undergoes an acid/base two-step reaction, in which hydrolysis and polycondensation proceed in acidic and basic aqueous media, respectively, as a one-pot reaction. Porous morphology is controlled by changing the concentration of F127. Sufficient concentrations of F127 inhibit the occurrence of micrometer-scale phase separation (spinodal decomposition) of hydrophobic PMSQ condensates and lead to well-defined mesoporous transparent aerogels with high specific pore volume as a result of the colloidal network formation in a large amount of solvent. Phase separation regulates well-defined macropores in the micrometer range on decreasing concentrations of F127. In the PMSQ-rich gelling domain formed by phase separation, the PMSQ colloidal network formation forms mesopores, leading to monolithic PMSQ gels with hierarchical macro- and meso-pore structures. Mesopores in these gels do not collapse on evaporative drying owing to the flexible networks and repulsive interactions of methyl groups in PMSQ. © 2011 Elsevier Inc.

DOI： 10.1016/j.jcis.2011.02.027

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Chromatography A  

Chromatographic properties of a new type of monolithic silica rod columns were examined. Silica rod columns employed for the study were prepared from tetramethoxysilane, modified with octadecylsilyl moieties, and encased in a stainless-steel protective column with two polymer layers between the silica and the stainless-steel tubing. A 25cm column provided up to 45,000 theoretical plates for aromatic hydrocarbons, or a minimum plate height of about 5.5μm, at optimum linear velocity of ca. 2.3mm/s and back pressure of 7.5MPa in an acetonitrile-water (80/20, v/v) mobile phase at 40°C. The permeability of the column was similar to that of a column packed with 5μm particles, with K F about 2.4×10 -14m 2 (based on the superficial linear velocity of the mobile phase), while the plate height value equivalent to that of a column packed with 2.5μm particles. Generation of 80,000-120,000 theoretical plates was feasible with back pressure below 30MPa by employing two or three 25cm columns connected in series. The use of the long columns enabled facile generation of large numbers of theoretical plates in comparison with conventional monolithic silica columns or particulate columns. Kinetic plot analysis indicates that the monolithic columns operated at 30MPa can provide faster separations than a column packed with totally porous 3-μm particles operated at 40MPa in a range where the number of theoretical plates (N) is greater than 50,000. © 2010 Elsevier B.V.

DOI： 10.1016/j.chroma.2010.11.032

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Sol-Gel Science and Technology  

Starting from calcium chloride dihydrate (CaCl2•2H 2O), phosphoric acid (H3PO4), and poly(acrylic acid) (PAA) dissolved in a mixture of water and methanol (MeOH), dicalcium phosphate anhydrous (DCPA, CaHPO4) monoliths with co-continuous macropores and mesopores have been synthesized by the addition of propylene oxide. Macropores are formed as a result of phase separation, while mesopores as interstices between primary particles with the size of ca. 30 nm. Propylene oxide acts as a proton scavenger and leads to moderate pH increase in a reaction solution, which brings about gelation in several minutes. On the other hand, PAA acts as a crystal growth inhibitor as well as a phase separation inducer. The extensive crystal growth of DCPA is hindered by the addition of PAA which allows morphological control of the structure in micrometer range. Fourier transform infrared spectroscopy indicates that PAA and DCPA form composite via interaction between the carboxyl groups and the surface of crystals, and together form gel phase. The solvent phase, which is converted to macropores after evaporative drying, is mainly comprised of solvent. The degree of supersaturation in a reaction solution considerably influence on the crystallization process, and thereby, influences on the porous structure in nano- and micrometer ranges. © 2010 Springer Science+Business Media, LLC.

DOI： 10.1007/s10971-010-2184-y

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Wiley-VCH  

DOI： 10.1002/9783527633241.ch5

Scopus

researchmap

記述言語：英語   掲載種別：論文集(書籍)内論文   出版者・発行元：Wiley-VCH  

DOI： 10.1002/9783527633241.ch2

Scopus

researchmap

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IOP Conference Series: Materials Science and Engineering  

Porous gel monolith was synthesized by reacting (3-mercaptopropyl) trimethoxysilane (MPTMS) with acetone on acidic conditions. It is known that MPTMS itself is difficult to turn into gel on acidic conditions and instead oligomers are obtained owing to the large mercaptopropyl group. In our system, the gels were obtained since acetone worked as a cross-linker via thioacetal reaction. Additionally, Au ions were selectively adsorbed on the obtained gel. When an obtained white gel was soaked in a chloroauric acid solution, the gel turned brown and was getting dark depending on the soaked time; on the other hand, the color of the solution turned from yellow to colorless. © 2011 Ceramic Society of Japan.

DOI： 10.1088/1757-899X/18/3/032003

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1088/1757-899X/18/3/032001

Web of Science

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IOP Conference Series: Materials Science and Engineering  

Hierarchically porous carbon monoliths with high specific surface areas have been fabricated by removing nano-sized silica phase from carbon/silica composites pyrolyzed from bridged poly(silsesquioxane). This activation method improves the homogeneity between inner and outer parts of the monoliths compared to the conventional thermal activation methods. © 2011 Ceramic Society of Japan.

DOI： 10.1088/1757-899X/18/3/032005

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

DOI： 10.1088/1757-899X/18/3/032013

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry  

Macro/meso/microporous carbon monoliths doped with sulfur have been prepared from sulfonated poly(divinylbenzene) networks followed by the activation with CO2 resulted in the activated carbon monoliths with high surface area of 2400 m2 g-1. The monolithic electrode of the activated carbon shows remarkably high specific capacitance (175 F g-1 at 5 mV s-1 and 206 F g-1 at 0.5 A g-1). © The Royal Society of Chemistry.

DOI： 10.1039/c0jm03793a

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Materials Chemistry  

We report new flexible "marshmallow-like" aerogels and xerogels with a bendable feature from the methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) co-precursor systems. A 2-step acid/base sol-gel process and surfactant are employed to control the phase separation of the hydrophobic networks, which give porous monolithic gels. The obtained gels become softer and more flexible with increasing DMDMS fractions. © 2011 The Royal Society of Chemistry.

DOI： 10.1039/c1jm13664j

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Journal of Colloid and Interface Science  

The structure formation process of hierarchically porous alumina gels has been investigated by in situ small angle X-ray scattering (SAXS). The measurement was performed on the sol-gel solution containing aluminum chloride hexahydrate (AlCl3·6H2O), poly(ethylene oxide) (PEO), and propylene oxide (PO). The temporal divergence of scattering intensity in the low q regime was observed in the early stage of reaction, indicating that the occurrence of spinodal-decomposition-type phase separation. Detailed analysis of the SAXS profiles revealed that phase separation occurs between weakly branched polymerizing aluminum hydroxide (AH) and PEO. Further progress of the condensation reaction forms phase-separated two phases, that is, AH-rich phase and PEO-rich phase with the micrometer-range heterogeneity. The growth and aggregation of primary particles occurs in the phase-separated AH-rich domain, and therefore, the addition of PEO influences on the structure in nanometer regime as well as micrometer regime. The moderate stability of oligomeric species allows homogeneous condensation reaction parallel to phase separation and successful formation of hierarchically porous alumina gel. © 2010 Elsevier Inc.

DOI： 10.1016/j.jcis.2010.08.041

Web of Science

Scopus

PubMed

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Microporous and Mesoporous Materials  

Using macroporous alumina as an aluminum source as well as structural support, high- and low-silica zeolites with trimodal pores have been fabricated in a monolithic form. Trimodally porous zeolites are obtained by the hydrothermal treatment of a monolithic alumina support impregnated with a mixture of AEROSIL 200, H2O, and sodium hydroxide or tetrapropylammonium hydroxide. The results of XRD measurement and 27Al NMR analysis reveal the formation of zeolites and the incorporation of Al into zeolite frameworks in tetrahedrally-coordinated environment. Low-silica zeolites, such as PHI- and ANA-type zeolites are formed when sodium hydroxide is utilized as a base and a structure directing agent (SDA). On the other hand, MFI-type zeolites are crystallized from highly supersaturated solutions with the use of tetrapropylammonium hydroxide. High alkaline resistance of alumina support enables the choice of wide range of OH-/SiO2 ratio, and moreover, the choice of desirable degree of supersaturation. As a result, the homogeneous crystallization of zeolites onto the alumina support has been successfully achieved. © 2010 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.micromeso.2010.04.005

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Applied Catalysis A: General  

Ni/TiO2 with bimodal pore structure was prepared from nickel nitrate and titanium alkoxide by a sol-gel process under acidic conditions in the presence of formamide. The Ni/TiO2 has continuous macropores which are formed by fixing the transitional structure of phase separation. Although the addition of nickel nitrate in the sol-gel reaction of titanium alkoxide steeply decreases the phase separation tendency, the macropore size can be controlled by changing the composition of preparation. The Ni/TiO 2 prepared by sol-gel has higher dispersion of Ni compared with that prepared by impregnation, and shows catalytic activity for the selective hydrogenation of crotonaldehyde: selectivity in the hydrogenation of C=C bond is much higher than that of C=O bond over sol-gel-derived Ni/TiO2. © 2010 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.apcata.2010.05.025

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Carbon  

Poly(divinylbenzene) (PDVB) monoliths with well-defined macropores that have been sulfonated and carbonized to obtain macroporous carbon monoliths. The original macroporous PDVB networks have been synthesized by living radical polymerization accompanied by spinodal decomposition. Sulfonation prevents polymer networks from large shrinkage and weight loss during carbonization by heat-treatment in an inert atmosphere. In the case of PDVB gels sulfonated at 120 °C using conc. H2SO4, mesopores in the original skeletons as well as macropores are retained after carbonization. The obtained carbon monoliths are subsequently activated by CO2, which resulted in activated carbons. The specific surface area of the obtained activated carbons reaches up to 2360 m2 g-1. © 2010 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.carbon.2010.01.019

Web of Science

Scopus

researchmap

その他リンク： http://orcid.org/0000-0002-8069-4780

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Chemistry of Materials  

Macroporous polysilsesquioxane monoliths have been synthesized from biphenylene-bridged alkoxysilane via the sol-gel transition and concurrent phase separation both induced by the polycondensation reaction. The obtained polysilsesquioxane gels have been subsequently converted to macroporous SiC/C composites by the carbothermal reduction. The SiC/C monoliths thus obtained involve no visible cracks and their porosity reaches as high as >90%. In addition, according to the nitrogen adsorption-desorption measurement results, the micro- and mesopore characteristics of the samples did not undergo a significant change during the carbothermal reduction and the SiC/C composites have large specific surface areas owing to the microporous carbons in the skeletons. These composites therefore are more suitable for the applications to gas storage and catalyst supports compared to pure SiC. © 2010 American Chemical Society.

DOI： 10.1021/cm9034616

Web of Science

Scopus

J-GLOBAL

researchmap

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Comptes Rendus Chimie  

Carbon monoliths with well-defined macropores and high surface areas were prepared by carbonization of macroporous poly(divinylbenzene) (PDVB) monoliths. The carbonization reactions of PDVB networks are studied by thermal analysis and FT-IR measurements. According to the measurement results, the PDVB networks are mostly pyrolyzed at 430 °C and their structures dynamically change to graphite-like structure between 600 and 700 °C. The macropore structure retained while the mesopores disappeared after carbonization. In addition, the surface area of the obtained carbons dramatically increased over 900 °C. The typical carbon monolith carbonized at 1000 °C for 2 h had a surface area of 1500 m2 g-1 and uniform macropores with a diameter of 1 μm. © 2009 Académie des sciences.

DOI： 10.1016/j.crci.2009.04.003

Web of Science

Scopus

J-GLOBAL

researchmap