The Experts below are selected from a list of 89871 Experts worldwide ranked by ideXlab platform
Yoshiki Chujo - One of the best experts on this subject based on the ideXlab platform.
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Microwave-enhanced hybridizations of biopolymers with silica: effective method for rapid preparation and homogeneous dispersion
Polymer Bulletin, 2011Co-Authors: Yuichi Kajiwara, Yoshiki ChujoAbstract:Effective hybridization of biopolymers such as chitosan or lignin was conducted by microwave-assisted sol–Gel Reaction of several alkoxysilanes such as tetramethoxysilane (TMOS), methyltrimethoxysilane (MeTMOS), and 3-aminopropyltrimethoxysilane (APTMS). The hybridization proceeded rapidly and efficiently via inhibition of aggregates derived from intermolecular hydrogen bonding in the biopolymers as compared with the conventional heating as a traditional method due to activated hydroxyl groups of both the biopolymers and alkoxysilanes by microwave irradiation. The composition and the thermal properties of the polymers hybridized under microwave irradiation were almost identical to those prepared by the conventional method using TGA analysis and FT-IR spectroscopy. However, the homogeneity on the surface of the hybrid obtained under microwave irradiation was better than that under conventional heating by measuring the SEM and nitrogen adsorption porosimetry analysis.
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synthesis and characterization of transparent poly 2 methyl 2 oxazoline pozo vanadium oxide v2o5 hybrids with reversible formation
Journal of Materials Chemistry, 2003Co-Authors: Tomoki Ogoshi, Yoshiki ChujoAbstract:Optically transparent and homogeneous polymer hybrids of poly(2-methyl-2-oxazoline) (POZO) and vanadium oxide (V2O5) can be prepared by utilizing the hydrogen bonding interactions between the amide groups of POZO and V–OH groups formed in the hydrolysis of vanadium(V) oxytripropoxide (TPVO). POZO acts as a stabilizer in the sol–Gel Reaction of TPVO, since this sol–Gel Reaction is too fast to obtain a transparent film without POZO. The amorphous state of the POZO–V2O5 hybrid was confirmed by DSC, SEM, and XRD. The polymer hybrids obtained can be reversibly dissolved in the solvents and cast again because of the amorphous state of vanadium(V) oxide. Moreover, the solubility of the polymer hybrids was dramatically changed by the reduction of V2O5 from V(V) to V(IV).
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polymer hybrids of functionalized silsesquioxanes and organic polymers utilizing the sol Gel Reaction of tetramethoxysilane
Polymer, 2002Co-Authors: Kaoru Adachi, Yoshiki ChujoAbstract:The ternary polymer hybrids were prepared by organic polymers such as poly(2-methyl-2-oxazoline) (POZO) or poly(N-vinylpyrrolidone) (PVP) and aminopropylsilsesquioxane (Cube-aminopropyl) utilizing the sol–Gel Reaction of tetramethoxysilane (TMOS). The prepared polymer hybrids were characterized by IR, thermogravimetric analysis (TGA), X-ray diffraction (XRD), 1H NMR, scanning electron microscopy (SEM), etc. In this hybrid system, hydrogen-bonding interactions played a critical role in the formation of the transparent polymer hybrids. Polymer hybrids using POZO showed high transparency and homogeneity in a wide range of the feed ratios of POZO to Cube-aminopropyl. On the other hand, in case of polymer hybrids using PVP, higher Cube-aminopropyl ratio brought about the phase separation, indicating the aggregation of the Cube-aminopropyl itself. The homogeneity of ternary polymer hybrids was found to be closely dependent on the difference between strength of hydrogen bonding interaction of polymer and residual silanol groups of silica Gel and strength of that of polymer and Cube-aminopropyl. It is also observed that initial decomposition temperature of polymer hybrids was increased with increasing the Cube-aminopropyl ratio.
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synthesis of organic inorganic polymer hybrids having interpenetrating polymer network structure by formation of ruthenium bipyridyl complex
Macromolecules, 2002Co-Authors: Tomoki Ogoshi, Hideaki Itoh, Yoshiki ChujoAbstract:Organic−inorganic polymer hybrids were prepared by an in-situ method. In the presence of ruthenium salt, the cross-linking Reaction of bipyridyl-containing polymer was carried out together with the sol−Gel Reaction of tetramethoxysilane. This methodology includes the simultaneous formation of silica Gel and organic Gel. Using polystyrene or poly(ethylene oxide) having bipyridyl groups, organic−inorganic polymer hybrids could be prepared. The obtained polymer hybrids having IPN (interpenetrating polymer network) structure showed excellent solvent-resistant property.
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Synthesis of Photoresponsive Organic-Inorganic Polymer Hybrids from Azobenzene-Modified Poly(2-methyl-2-oxazoline)
Macromolecules, 1998Co-Authors: Yusuke Imai, Kensuke Naka, Yoshiki ChujoAbstract:Transparent and homogeneous polymer hybrids could be obtained in a wide range of composition by th acid-catalyzed sol-Gel Reaction of alkoxysilanes in the presence of azobenzene-modified poly(2-methyl-5-oxazoline) (POZO). It is confirmed that both trans-to-cis photoisomerization and thermal or photochemical cis-to-trans reverse isomerization of azobenzene chromophores took place reversibly in the POZO/methyltrimethoxysilane
Taeghwan Hyeon - One of the best experts on this subject based on the ideXlab platform.
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large scale synthesis of bioinert tantalum oxide nanoparticles for x ray computed tomography imaging and bimodal image guided sentinel lymph node mapping
Journal of the American Chemical Society, 2011Co-Authors: Nohyun Lee, Seung Hong Choi, Hyoungsu Kim, Seung Pyo Park, Yuanzhe Piao, Jisoo Lee, Samuel Woojoo Jun, Woo Kyung Moon, Taeghwan HyeonAbstract:Ever since Au nanoparticles were developed as X-ray contrast agents, researchers have actively sought alternative nanoparticle-based imaging probes that are not only inexpensive but also safe for clinical use. Herein, we demonstrate that bioinert tantalum oxide nanoparticles are suitable nanoprobes for high-performance X-ray computed tomography (CT) imaging while simultaneously being cost-effective and meeting the criteria as a biomedical platform. Uniformly sized tantalum oxide nanoparticles were prepared using a microemulsion method, and their surfaces were readily modified using various silane derivatives through simple in situ sol−Gel Reaction. The silane-modified surface enabled facile immobilization of functional moieties such as polyethylene glycol (PEG) and fluorescent dye. PEG was introduced to endow the nanoparticles with biocompatibility and antifouling activity, whereas immobilized fluorescent dye molecules enabled simultaneous fluorescence imaging as well as X-ray CT imaging. The resulting na...
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large scale synthesis of water dispersible ceria nanocrystals by a simple sol Gel process and their use as a chemical mechanical planarization slurry
European Journal of Inorganic Chemistry, 2008Co-Authors: Taekyung Yu, Yong Il Park, Mincheol Kang, Jin Kyung Park, Taeghwan HyeonAbstract:Ceria nanocrystals with a cube shape were synthesized from the hydrolytic sol–Gel Reaction of cerium salt in the presence of oleylamine. The overall synthetic process is very simple and readily applicable to the large-scale synthesis of tens of grams of product in a single Reaction in air. These ceria nanocrystals are readily dispersible in aqueous media without the addition of any extra dispersing agent. The aqueous dispersion of the ceria nanocrystals was successfully used as a chemical mechanical polishing slurry, and it exhibited high removal selectivity between silicon oxide and silicon nitride at pH 7.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
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simultaneous phase and size controlled synthesis of tio2 nanorods via non hydrolytic sol Gel Reaction of syringe pump delivered precursors
Journal of Physical Chemistry B, 2006Co-Authors: Bonil Koo, Jongnam Park, Yukyeong Kim, Sanghyun Choi, Yungeun Sung, Taeghwan HyeonAbstract:The simultaneous phase- and size-controlled synthesis of TiO2 nanorods was achieved via the non-hydrolytic sol−Gel Reaction of continuously delivered two titanium precursors using two separate syringe pumps. As the injection rate was decreased, the length of the TiO2 nanorods was increased and their crystalline phase was simultaneously transformed from anatase to rutile. When the Reaction was performed by injecting titanium precursors contained in two separate syringes into a hot oleylamine surfactant solution with an injection rate of 30 mL/h, anatase TiO2 nanorods with dimensions of 6 nm (thickness) × 50 nm (length) were produced. When the injection rate was decreased to 2.5 mL/h, star-shaped rutile TiO2 nanorods with dimensions of 25 nm × 200 nm and a small fraction of rod-shaped anatase TiO2 nanorods with dimensions of 9 nm × 100 nm were synthesized. Pure star-shaped rutile TiO2 nanorods with dimensions of 25 nm × 450 nm were synthesized when the injection rate was further decreased to 1.25 mL/h. The ...
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simultaneous phase and size controlled synthesis of tio2 nanorods via non hydrolytic sol Gel Reaction of syringe pump delivered precursors
Journal of Physical Chemistry B, 2006Co-Authors: Bonil Koo, Jongnam Park, Yukyeong Kim, Sanghyun Choi, Yungeun Sung, Taeghwan HyeonAbstract:The simultaneous phase- and size-controlled synthesis of TiO(2) nanorods was achieved via the non-hydrolytic sol-Gel Reaction of continuously delivered two titanium precursors using two separate syringe pumps. As the injection rate was decreased, the length of the TiO(2) nanorods was increased and their crystalline phase was simultaneously transformed from anatase to rutile. When the Reaction was performed by injecting titanium precursors contained in two separate syringes into a hot oleylamine surfactant solution with an injection rate of 30 mL/h, anatase TiO(2) nanorods with dimensions of 6 nm (thickness) x 50 nm (length) were produced. When the injection rate was decreased to 2.5 mL/h, star-shaped rutile TiO(2) nanorods with dimensions of 25 nm x 200 nm and a small fraction of rod-shaped anatase TiO(2) nanorods with dimensions of 9 nm x 100 nm were synthesized. Pure star-shaped rutile TiO(2) nanorods with dimensions of 25 nm x 450 nm were synthesized when the injection rate was further decreased to 1.25 mL/h. The simultaneous phase transformation and length elongation of the TiO(2) nanorods were achieved. Under optimized Reaction conditions, as much as 3.5 g of TiO(2) nanorods were produced. The TiO(2) nanorods were used to produce dye-sensitized solar cells, and the photoconversion efficiency of the mixture composed of star-shaped rutile TiO(2) nanorods and a small fraction of anatase nanorods were comparable to that of Degussa P-25.
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multigram scale synthesis and characterization of monodisperse tetragonal zirconia nanocrystals
Journal of the American Chemical Society, 2003Co-Authors: Jin Joo, Youngwoon Kim, Hyunmin Park, Jin Z Zhang, Taeghwan HyeonAbstract:A new and simple method has been developed to synthesize large quantities of highly monodisperse tetragonal zirconia nanocrystals. In this synthesis, a nonhydrolytic sol−Gel Reaction between zirconium(IV) isopropoxide and zirconium(IV) chloride at 340 °C generated 4 nm sized zirconia nanoparticles. A high-resolution transmission electron microscopic (HRTEM) image showed that the particles have a uniform particle size distribution and that they are highly crystalline. These monodisperse nanoparticles were synthesized without any size selection process. X-ray diffraction studies combined with Rietveld refinement revealed that the ZrO2 nanocrystals are the high-temperature tetragonal phase, and very close to a cubic phase. When zirconium(IV) bromide is used as a precursor instead of zirconium chloride, zirconia nanoparticles with an average size of 2.9 nm were obtained. The UV−visible absorption spectrum of 4 nm sized zirconia nanoparticles exhibited a strong absorption starting at around 270 nm. A fluoresce...
Yong Qian - One of the best experts on this subject based on the ideXlab platform.
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the synthesis of a novel graphene based inorganic organic hybrid flame retardant and its application in epoxy resin
Composites Part B-engineering, 2014Co-Authors: Zehao Wang, Yong QianAbstract:Abstract In this paper, a novel graphene-based inorganic–organic hybrid flame retardant (GFR) was prepared via sol–Gel Reaction of FGO and phenyl-bis-(triethoxysilylpropyl) phosphamide (PBTP) and characterized by FT-IR, XPS, XRD, TGA and AFM. The influence of the GFR on the thermal stability and flame retardance of epoxy resin composites were characterized by TGA, LOI as well as micro-cone, which indicated that GFR brought a good effect in enhancing the residual char and flame retardance of epoxy composites. The dynamic mechanical properties and electrical properties of EP composites were also analyzed.
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the synthesis of a novel graphene based inorganic organic hybrid flame retardant and its application in epoxy resin
Composites Part B-engineering, 2014Co-Authors: Zehao Wang, Yong Qian, Ping Wei, Jiping LiuAbstract:Abstract In this paper, a novel graphene-based inorganic–organic hybrid flame retardant (GFR) was prepared via sol–Gel Reaction of FGO and phenyl-bis-(triethoxysilylpropyl) phosphamide (PBTP) and characterized by FT-IR, XPS, XRD, TGA and AFM. The influence of the GFR on the thermal stability and flame retardance of epoxy resin composites were characterized by TGA, LOI as well as micro-cone, which indicated that GFR brought a good effect in enhancing the residual char and flame retardance of epoxy composites. The dynamic mechanical properties and electrical properties of EP composites were also analyzed.
Zehao Wang - One of the best experts on this subject based on the ideXlab platform.
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the synthesis of a novel graphene based inorganic organic hybrid flame retardant and its application in epoxy resin
Composites Part B-engineering, 2014Co-Authors: Zehao Wang, Yong QianAbstract:Abstract In this paper, a novel graphene-based inorganic–organic hybrid flame retardant (GFR) was prepared via sol–Gel Reaction of FGO and phenyl-bis-(triethoxysilylpropyl) phosphamide (PBTP) and characterized by FT-IR, XPS, XRD, TGA and AFM. The influence of the GFR on the thermal stability and flame retardance of epoxy resin composites were characterized by TGA, LOI as well as micro-cone, which indicated that GFR brought a good effect in enhancing the residual char and flame retardance of epoxy composites. The dynamic mechanical properties and electrical properties of EP composites were also analyzed.
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the synthesis of a novel graphene based inorganic organic hybrid flame retardant and its application in epoxy resin
Composites Part B-engineering, 2014Co-Authors: Zehao Wang, Yong Qian, Ping Wei, Jiping LiuAbstract:Abstract In this paper, a novel graphene-based inorganic–organic hybrid flame retardant (GFR) was prepared via sol–Gel Reaction of FGO and phenyl-bis-(triethoxysilylpropyl) phosphamide (PBTP) and characterized by FT-IR, XPS, XRD, TGA and AFM. The influence of the GFR on the thermal stability and flame retardance of epoxy resin composites were characterized by TGA, LOI as well as micro-cone, which indicated that GFR brought a good effect in enhancing the residual char and flame retardance of epoxy composites. The dynamic mechanical properties and electrical properties of EP composites were also analyzed.
Farid R Zaggout - One of the best experts on this subject based on the ideXlab platform.
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behavior of immobilized alizarin red s into sol Gel matrix as ph sensor
Materials Letters, 2007Co-Authors: Farid R Zaggout, Abed El-fattah A. Qarraman, Shehata M. ZourabAbstract:Abstract The preparation of transparent monolithic silica doping with Alizarin Red S was carried out by acid catalyzed sol–Gel Reaction of tetraethylorthosilicate (TEOS) in the presence of Alizarin Red S. The immobilized Alizarin Red S pH indicator shows similar behavior as its solution counterpart. The UV/VIS spectra indicate that the Alizarin Red S retains its structure during the sol–Gel Reactions in terms of response to pH. Therefore, the Alizarin Red S can be regarded as uniformly distributed in the sol–Gel matrix. Also, addition of the dye plus SDS into the sol–Gel matrix modifies the structure of the net work and makes it more homogeneous and increases the surface area. These characteristics were justified by using polarized microscope technique.
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behavior of thymol blue analytical ph indicator entrapped into sol Gel matrix
Materials Letters, 2006Co-Authors: Farid R Zaggout, Issa M Elnahhal, Abed Elfattah A Qaraman, Naji Al DahoudiAbstract:Abstract The preparation of transparent monolithic silica doping with thymol blue has been carried out by the acid catalyzed sol–Gel Reaction of tetraethylorthosilicate in the presence of thymol blue. The immobilized thymol blue pH-indicator shows similar behavior as its solution counterpart. The UV/VIS spectra indicate that the thymol blue retains its structure during the sol–Gel Reactions in terms of response to pH. Thymol blue can be regarded as uniformly distributed in the sol–Gel matrix, and the use of SDS surfactant has positive effects on the immobilized thymol blue monolithic disk by homogenizing the polymerizing system. This research shows that thymol blue indicator can be used as solid pH sensor.
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entrapment of phenol red ph indicator into a sol Gel matrix
Materials Letters, 2006Co-Authors: Farid R ZaggoutAbstract:Abstract Entrapment of phenol red pH indicator into transparent monolithic silica matrices, was made by the acid catalyzed sol–Gel Reaction of tetraethylorthosilicate and the phenol red indicator. The immobilized phenol red shows similar behavior as its solution counterpart. It retains its structure during the sol–Gel Reactions in terms of response to pH. The polarized light microscopy has indicated that the phenol red molecules are strongly interacted within the host silica network. The successful encapsulation of phenol red results in using it as solid indicator.
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encapsulation of bromothymol blue ph indicator into a sol Gel matrix
Journal of Dispersion Science and Technology, 2006Co-Authors: Farid R ZaggoutAbstract:Transparent monolithic silica doping with bromothymol blue has been prepared by the acid catalyzed sol‐Gel Reaction of tetraethylorthosilicate in the presence of bromothymol blue. The immobilized bromothymol blue shows behavior similar to its solution counterpart. It retains its structure during the sol‐Gel Reactions in terms of response to pH. Polarized light microscopy has indicated that the bromothymol blue molecules are strongly interacted within the host silica network. The immobilization of bromothymol blue into sol‐Gel matrix could be used as a solid indicator.
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encapsulation of bromocresol green ph indicator into a sol Gel matrix
Journal of Dispersion Science and Technology, 2005Co-Authors: Farid R ZaggoutAbstract:The bromocresol green pH indicator was encapsulated into transparent monolithic silica matrices using acid catalyzed sol‐Gel Reaction. Tetraethylorthosilicate was used for the entrapment of the bromocresol green indicator. The immobilized bromocresol green shows behavior similar to its solution counterpart. It retains its structure during the sol‐Gel Reactions in terms of response to pH and albumine. The polarized light microscopy has indicated that the bromocresol green molecules are strongly interacted within the host silica network.
