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排序方式: 共有126条查询结果,搜索用时 15 毫秒
91.
Hideki Sugihara Hiroki Murase Keiji Tanaka Atsushi Takahara 《Applied Surface Science》2008,254(10):3180-3183
A novel experimental technique for three-dimensional (3D) visualization of phase-separated structure of polymer blend thin film was proposed. Polystyrene/poly(methyl methacrylate) (PS/PMMA) blend thin films with the thickness of approximately 100 nm were cut at extremely low angle by utilizing surface and interface cutting analysis system (SAICAS), and the cross-section was exposed as gradient surface with the width of approximately 2.5 μm. SFM investigation for the grazing cross-section imaged the detailed internal and surface phase separated structure of the (PS/PMMA) blend thin films on one image. 相似文献
92.
93.
Takahara S Sumiyama N Kittaka S Yamaguchi T Bellissent-Funel MC 《The journal of physical chemistry. B》2005,109(22):11231-11239
Quasielastic neutron scattering (QENS) spectra of water-filled MCM-41 samples (pore diameters: 21.4 and 28.4 Angstrom) were measured over the temperature range 238-298 K and the momentum transfer range 0.31-0.99 A(-1) to investigate the dynamics of confined water molecules. The spectra, which consist mainly of contributions from the translational diffusion of water molecules, were analyzed by using the Lorentzian and the stretched exponential functions. Comparison of the fits indicated that the latter analysis is more reliable than the former one. The fraction of immobile water molecules located in the vicinity of the pore walls, which give an elastic component, was found to be 0.044-0.061 in both pores. The stretch exponent beta was determined as 0.66-0.80. It was shown that the translational diffusion of water molecules in the pores is decelerated by confinement and that the deceleration becomes marked with a decrease in pore size. The ratios of the translational diffusion coefficient D(T) of confined water to that of bulk water at room temperature were within a range of 0.47-0.63. 相似文献
94.
Dependence of the molecular aggregation state of octadecylsiloxane monolayers on preparation methods
Koga T Morita M Ishida H Yakabe H Sasaki S Sakata O Otsuka H Takahara A 《Langmuir : the ACS journal of surfaces and colloids》2005,21(3):905-910
The molecular aggregation state of octadecylsiloxane monolayers on Si-wafer substrate surfaces prepared from octadecyltrimethoxysilane (OTMS) or octadecyltrichlorosilane (OTS) was investigated on the basis of grazing incidence X-ray diffraction (GIXD), Fourier transform infrared spectroscopy (FT-IR), contact angle measurement, field emission scanning electron microscopy (FE-SEM), and scanning force microscopy (SFM). The OTMS monolayer was prepared by using the chemical vapor adsorption (CVA) method, and the OTS monolayers, which were used as reference samples, were prepared either by chemisorption (OTS-S) or by the water-cast method (OTS-W). The GIXD, FT-IR, lateral force microscopic (LFM) measurements, and FE-SEM observation revealed that the alkyl chains in the OTMS monolayers prepared using the CVA method are in an amorphous state at room temperature. According to the LFM measurement, the transition temperature from the hexagonal crystalline phase to the amorphous phase was found to be ca. 333 K for the OTS-S monolayer prepared by the chemisorption method. However, the phase transition was not observed in the OTMS monolayer prepared by the CVA method. Also, the atomic force microscopic (AFM) observation and the contact angle measurement showed that the OTMS monolayer prepared by the CVA method has a uniform surface when compared to the OTS monolayers. These results indicated that organosilane compounds in the monolayer prepared by the CVA method were immobilized on the Si-wafer substrate surface in an amorphous state, which was quite different from the hexagonal crystalline state obtained by the chemisorption and water-cast methods. 相似文献
95.
Takamuku T Maruyama H Kittaka S Takahara S Yamaguchi T 《The journal of physical chemistry. B》2005,109(2):892-899
Large-angle X-ray scattering (LAXS) measurements over a temperature range from 223 to 298 K have been made on methanol confined in mesoporous silica MCM-41 with two different pore diameters, 28 A (C14) and 21 A (C10), under both monolayer and capillary-condensed adsorption conditions. To compare the structure of methanol in the MCM-41 pores with that of bulk methanol, X-ray scattering intensities for bulk methanol in the same temperature range have also been measured. The radial distribution functions (RDFs) for the monolayer methanol samples showed that methanol molecules are strongly hydrogen bonded to the silanol groups on the MCM-41 surface, resulting in no significant change in the structure of adsorbed methanol with respect to the pore size and temperature. On the other hand, the RDFs for the capillary-condensed methanol samples showed that hydrogen-bonded chains of methanol molecules are formed in both pores. However, the distance and number of hydrogen bonds estimated from the RDFs suggested that hydrogen bonds between methanol molecules in the pores are significantly distorted or partly disrupted. It has been found that the hydrogen bonds are more distorted in the smaller pores of MCM-41. With decreasing temperature, however, the hydrogen-bonded chains of methanol in the pores were gradually ordered. A comparison of the present results on methanol in MCM-41 pores with those on water in the same pores revealed that the structural change with temperature is less significant for confined methanol than for confined water. 相似文献
96.
Megumu Inaba Kazuhisa Murata Masahiro Saito Isao Takahara 《Reaction Kinetics and Catalysis Letters》2006,88(1):135-141
Summary H-ZSM-5 (Si/Al2 = 29) zeolite showed especially high activity in the conversion of ethanol to BTX (benzene, toluene, xylenes), while other
zeolites exclusively formed ethylene. Noble metal catalysts supported on H-ZSM-5 (29) zeolite have high activity for the formation
of BTX. Of these, Au/H-ZSM-5 catalyst can partially inhibit carbon deposition during the reaction, thus maintaining constant
catalytic activity for BTX formation. 相似文献
97.
Otsuka H Aotani K Higaki Y Takahara A 《Chemical communications (Cambridge, England)》2002,(23):2838-2839
A dynamic covalent polymer incorporating thermally alkoxyamine units in the main chain was synthesized. Due to a radical crossover reaction between the alkoxyamine units, an interchange of the main chains in poly(alkoxyamine ester) was observed on heating. 相似文献
98.
Takahara YK Ikeda S Tachi K Sakata T Hasegawa T Mori H Matsumura M Ohtani B 《Chemical communications (Cambridge, England)》2005,(33):4205-4207
Production of porous polystyrene microspheres having dimpled surface structures was demonstrated using amphiphilic and hydrophobic silica particles as structure-directing agents. 相似文献
99.
Kazuhisa Murata Isao Takahara Megumu Inaba 《Reaction Kinetics and Catalysis Letters》2008,93(1):59-66
Solid acid supports such as H-ZSM5, H-Mordenite, γ-Al2O3, USY and Beta catalysts were modified with Pt. These Pt/oxide catalysts were found to be active for propane formation through
aqueous reforming of glycerol in the presence of hydrogen. The reforming reactions, possibly, proceeded through reaction cycles
of dehydration on acid sites and hydrogenation on Pt sites over the catalysts. 相似文献
100.
X‐ray absorption fine structure study on the role of solvent on polymerization of 3‐hexylthiophene with solid FeCl3 particles 下载免费PDF全文
Tomoyasu Hirai Masanao Sato Makoto Kido Yusuke Nagae Katsuhiro Kaetsu Yudai Kiyoshima Shota Fujii Tomoyuki Ohishi Kevin L. White Yuji Higaki Yasutake Teraoka Maiko Nishibori Kazutaka Kamitani Kenji Hanada Takeharu Sugiyama Ryuichi Sugimoto Kazuhiko Saigo Ken Kojio Atsushi Takahara 《Journal of polymer science. Part A, Polymer chemistry》2015,53(18):2075-2078