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941.
Oun-Ho Park Young-Joo Eo Yoon-Ki Choi Byeong-Soo Bae 《Journal of Sol-Gel Science and Technology》1999,16(3):235-241
Structural evolution and optical properties of the silica-poly(ethylene oxide) hybrid films prepared from -glycidoxypropyltrimethoxysilane (GPTS) and 1-methylimidazol (MI) are studied. Polymerization of the epoxy groups is achieved by using 1-methylimidazol as a thermal curing agent. In liquid state 1H &13 C NMR spectroscopy, it is found that silica condensation mainly occurs without epoxy ring opening. The epoxide polymerization is confirmed by using FT-IR, solid state CP-MAS 13C-NMR, and differential scanning calorimetry (DSC). The hybrid material is densified due to the epoxide polymerization as well as silica condensation with thermal curing. As a result, the thermal curing increases refractive index and extinction coefficient and shifts UV optical absorption edge to longer wavelength. 相似文献
942.
A. Vergnes M. Nobili P. Delord Luca Cipelletti R.J.P. Corriu B. Boury 《Journal of Sol-Gel Science and Technology》2003,26(1-3):621-624
A new type of hybrid material is prepared through sol-gel processing by the polycondensation of (MeO)3Si–R–Si(OMe)3 units containing a rigid organic anisotropic group R. The hybrid covalently bounded organic-inorganic gel shows an unexpected structural birefringence n (n = 2 × 10–3). This birefringence is induced by a strain field anisotropy during gel aging as revealed by simultaneous dynamic light scattering and birefringence measurements. To better address the role of the strain field, we use a free interface sol-gel/air to control strain anisotropy and to measure the gel optical axis and its birefringence. We find that the birefringence is associated to a long-range orientational order of organic moieties induced by the strain anisotropy during the gel aging. 相似文献
943.
You-Kyong Seo 《Journal of solid state chemistry》2006,179(4):1285-1288
Mesoporous hybrid material containing urethane moieties in functionalized long chain organic group have been synthesized by using bis[3-(triethoxysilyl) propyl urethane]ethane (BTESPUE) and tetraethoxysilane as structural ingredients. The incorporation of BTESPUE within the framework of mesoporous material was confirmed by Fourier transform-infrared, X-ray photoelectron spectroscopy, solid-state NMR spectroscopy and thermogravimetric analysis. This material had a thick wall and uniform pore, which may be attributed to the hydrogen bonding inside framework due to urethane moieties. 相似文献
944.
Minoru Kuniyoshi Masahide Takahashi Yomei Tokuda Toshinobu Yoko 《Journal of Sol-Gel Science and Technology》2006,39(2):175-183
The effects of acid catalyst, water content and reaction temperature on the hydrolysis and polycondensation of phenyltriethoxysilane
(PhTES) were studied using 29Si NMR spectroscopy. The sol catalyzed by hydrochloric acid showed the simultaneous progress of hydrolysis and polycondensation.
In addition, the reaction rate was almost independent of reaction temperature. On the other hand, the polycondensation in
the PhTES-derived sol mixed with an excess amount of water and acetic acid as a catalyst proceeded after completion of the
hydrolysis. In the acetic acid-catalyzed system, the degree of the hydrolysis and polycondensation largely depends on the
reaction temperature. 相似文献
945.
The conductivity behavior of Al(OH)3-acrylamide hybrid polyacrylamide (hybrid PAAm) in distilled water was studied. A discontinuity phenomenon of the conductivity (k) versus concentration (c) curve of the hybrid PAAm in a certain concentration regime is found. This phenomenon is dependent on the molecular weight of the hybrid PAAm and on the particle size and content of the AI(OH)3 colloid in the hybrid PAAm. This phenomenon was accounted for assuming ionization of the hybrid PAAm. 相似文献
946.
Hybrid inorganic-organic hard coatings on PMMA substrate were obtained by sol-gel reaction of 3-glycidoxypropyltrimethoxysilane(GPTS), tetramethyl orthosilicate(TMOS) and aluminum butoxyethoxide (Al(OEtOBu)3). The catalytic effect of aluminum butoxyethoxide on inorganic condensation and epoxide polymerization has been studied by 13C, 29Si nuclear magnetic resonance spectroscopy and by Fourier transformed infrared spectroscopy. Hardness of hybrid inorganic-organic materials were measured by nanoindentor and mainly influenced by the extent of epoxide polymerization and inorganic condensation of their coating catalyzed by aluminum butoxyethoxide. 相似文献
947.
Angeloni A Crawford PC Orpen AG Podesta TJ Shore BJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(15):3783-3791
The preparation and structure determinations of the crystalline salts [3,3'-H(2)bipy][PtCl(4)] (2), [2,2'-H(2)bipy][PtCl(4)] (3) and [1,4'-Hbipy][PtCl(4)] (4) and [3,3'-H(2)bipy][SbCl(5)] (6) and [1,4'-Hbipy][SbCl(5)] (8) are reported. In addition a redetermination of the structure of the metastable salt [4,4'-H(2)bipy][SbCl(5)] (5 b) in the corrected space group Pbcm is described. These structures are compared to those of the known salt [4,4'-H(2)bipy][PtCl(4)] (1), the stable triclinic form of [4,4'-H(2)bipy][SbCl(5)] (5 a) and [2,2'-H(2)bipy][SbCl(5)] (7). In the case of the salts of the rigid [PtCl(4)](2-) ion, structures 2, 3 and 4 are essentially isostructural despite the differing hydrogen-bonding capability of the cations. Similarly, among the salts of [SbCl(5)](2-) ions, structures 7 and 8 are essentially isostructural. Structure 6 differs from these in having a differing pattern of aggregation of the [SbCl(5)](2-) ions to form polymeric rather than tetrameric units. It is evident that local hydrogen-bonding interactions, although significant, are not the only or even the decisive influence on the crystal structures formed by these salts. These observations are not in good accord with the heuristic "sticky tecton" or supramolecular synthon models for synthetic crystallography or crystal engineering. 相似文献
948.
The electroreduction of eosin Y on a platinum electrode in deaerated slightly acidic aqueous 0.1 mol L(-1) potassium chloride medium is followed in situ by electron spin resonance (ESR) spectroscopy and UV/Vis spectroscopy. The electrochemical formation of a semiquinone radical is proved by both the appearance of an absorbing band at 408 nm, and a strong ESR signal observed during a negative-going scan. The system is also studied in the presence of Zn(II) ions due to its importance for understanding the growth mechanism of nanostructured ZnO/Eosin Y hybrid films by electrodeposition; under such conditions the ESR and UV/Vis response of the semiquinone radical is not observed. Zinc (II) ions form a complex with the dye, which is reduced by a fast two-electron process. 相似文献
949.
950.
A hybrid multilayered "ONIOM"-type approach to solvation is presented in which the basic free energy of hydration is taken from the Poisson Boltzmann method and the contribution to the solute polarization is taken from a quantum mechanical implementation of the Born method. The method has been tested on the 52 neutral molecules used in the AM1-SM2 parameterization, and the polarized continuum method is taken as the standard by which the results are assessed. Regression analysis shows that the method gives a small improvement over the standard Poisson Boltzmann method or a dramatic improvement over the Born method. The system presented here represents one of the more straightforward applications of the multilayered approach to solvation, but other more sophisticated approaches are discussed. 相似文献