共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
溶胶—凝胶法制备有机—无机纳米复合材料 总被引:19,自引:0,他引:19
溶胶-凝胶法以其温和的反应条件,尤其是低的反应温度成为有机-无机纳米复合材料制备的最有效的方法.本文根据合成路线的不同,分5个方面对用溶胶-凝胶法制备复合材料进行概要介绍. 相似文献
3.
4.
5.
6.
7.
在水热体系下,通过溶胶-凝胶法,以阳离子表面活性剂十六烷基三甲基溴化铵作为模板剂,正硅酸乙酯作为硅源,三氯化钛作为钛源,制备出Ti/Si复合材料。样品的结构和形貌采用X射线衍射、扫描电子显微镜和透射电子显微镜进行表征,结果表明,所得样品呈现10 nm左右的层状形貌,同时具有相对规则的微孔结构,为其在催化氧化方面提供了有利条件,也为实验教材中Ti/Si复合材料的制备奠定了理论基础。 相似文献
8.
9.
10.
新颖的玻璃制备方法—溶胶—凝胶法 总被引:10,自引:0,他引:10
长期以来,玻璃和光学纤维玻璃的制备几乎都是使用熔融—冷却法。这种方法不仅需要昂贵的生产设备,而且难以得到高纯度和高均匀度的材料。尤其是对于一些具有特殊结构和高熔点的玻璃材料,熔融—冷却法往往无能为力。 相似文献
11.
P. Egger S. Dirè M. Ischia R. Campostrini 《Journal of Thermal Analysis and Calorimetry》2005,81(2):407-415
Summary A homogeneous ZrO2 gel was obtained by hydrolysis-condensation of zirconium(IV) n-propoxide previously reacted with acetic acid. Dried zirconia powders were characterized by Fourier transformed infra-red (FTIR) and X-ray diffraction (XRD) analyses. Thermogravimetric (TG) and differential thermal analysis (DTA) coupled with mass spectrometric (MS) and gas chromatographic (GC) measurements were carried out in order to identify and quantify the organic products released during the ZrO2 gel pyrolysis. The TG-MS semi-quantitative analysis of the main released species allowed to describe the chemical rearrangement occurring in the solid during heating and to determine the chemical composition of the initial gel. 相似文献
12.
Kun-Hong Lee Yung-Pyo Koh Jae-Gon Lim 《Journal of Sol-Gel Science and Technology》1994,2(1-3):907-912
Silica glass was synthesized form TEOS and deionized water using sol-gel process. To introduce the physicochemical effects of ultrasonic waves, an ultrasonic homogenizer was used to mix reactants instead of adding cosolvents. 2-step method was chosen to separate hydrolysis reaction and condensation reaction, and thus to control the microstructure of wet gels. Wet gels were dried in 5–8 hours without cracks using supercritical drying with ethanol at 300°C and 10.34 MPa. Aerogels thus obtained have hydrophobic surfaces due to the reesterification reactions during supercritical drying. Aerogels were sintered in a tube furnace in the changing atmosphere from N2 through O2 to He. Sudden volume change was started at 1050°C and sintering was completed at 1100°C as expected. Large pores of aerogels allowed fast sintering in 16 and a half hours. Incomplete extraction in supercritical drying step produced crystals during sintering. 相似文献
13.
sol-gel 法在有机-无机杂化体系中制备二氧化硅微粒 总被引:1,自引:0,他引:1
利用sol-gel法,通过正硅酸乙酯(tetraethyl orthosilicate(TEOS))在聚氧化乙烯/二甲基甲酰胺溶液中水解、缩聚,制备了粒径分布均匀的微米级二氧化硅粒子;利用扫描电子显微镜观测了制备条件对二氧化硅粒子的粒度和形貌的影响;研究了这一方法在制备无机粒子过程中的原理. 相似文献
14.
Tanaka H Yamada T Sugiyama S Shiratori H Hino R 《Journal of colloid and interface science》2005,286(2):812-815
Using a hydroxyl group appended free base porphyrin derivative (HP), porphyrin-introduced silica gels were synthesized by a sol-gel process. The HP content in the materials linearly increased with increasing the HP concentration. Meanwhile, free base tetraphenylporphyrin (TPP) with no hydroxyl groups were almost not incorporated into the silica gels. These facts suggested that the interaction between hydroxyl groups of the HP molecules and silica network is considerably strong. The UV-vis characters of HP-introduced materials were almost the same as pure HP molecules. The Beer's plot indicated that the HP molecules in the materials are dispersed. 相似文献
15.
Mesoporous silica materials with pore diameters of 2-5 nm have been prepared using ascorbic acid as a nonsurfactant template or pore-forming agent in HCl-catalyzed sol-gel reactions of tetraethylorthosilicate,followed by removing the ascorbic acid compound by extraction with ethanol.Characterization results from nitrogen sorption isotherm,powder X-ray diffraction and transmission electron microscopy indicate that the materials have large specific surface areas (e.g.1000 m2/g) and pore volumes (e.g.0.8 cm3/g).The rnesoporosity is arisen from interconnecting disordered wormlike channels and pores with relatively broad size distributions.As the ascorbic acid concentration is increased,the pore diameters and pore volumes of the materials increase. 相似文献
16.
YuYingFENG XiaoTianGU JiaHongZHOU JianChunBAO GangLI TianHongLU 《中国化学快报》2004,15(12):1505-1508
New Ge/SiO2 glasses have been synthesized by heating the GeO2/SiO2 dry gels under H2 gas at 700℃. The resulting fluorescence spectra show that this kind of Ge/SiO2 glasses emit strong photoluminescence at 392 nm (3.12 eV), medium strong photoluminescence at 600 nm (2.05 eV) and weak photoluminescence at 770 nm (1.60 eV) respectively. Possible photoluminescence mechanisms are also discussed based on the results of X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS). 相似文献
17.
Pyrolysis study of fluorinated sol-gel silica 总被引:1,自引:0,他引:1
Fluorinated silica gels at various fluorine content were prepared via sol-gel by hydrolysis of 3,3,3-trifluoropropyltrimethoxysilane
and tetraethoxysilane mixtures. The gels, of nominal stoichiometry Si(CH2CH2CF3)XO(2-X/2)(X=0.1-1), were characterized by FT-IR, X-ray photoelectron spectroscopy (XPS) and N2 adsorption analysis. The thermal stability of the fluorinated samples was investigated by coupling thermogravimetric measurements
with mass spectrometric and gas chromatographic analyses of the evolved gaseous species. The chemical reactions occurring
in the gel matrices during heating were siloxane chain rearrangements involving condensation between residual hydroxyl and
ethoxyl groups in the 100-350°C temperature range, whereas the thermal decomposition of the fluoroalkyl groups were observed
at higher temperatures (450-600°C). The release of the fluoroalkyl moieties also involved C-F/Si-O bond exchanges inside the
siloxane chains, with gas-phase evolution of different fluorinated silicon units.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
19.
A novel flexible free-standing films of polyvinyl alcohol (PVA)/silica polymer network dispersed cholesteric liquid crystals (CLC) have been prepared by the sol-gel process. In the hydrolysis of silicon alkoxides tetraethoxysilane (TEOS) processes, the silica having -OH with the -OH groups on PVA formed polymer networks with Si-O-C bonds by dehydration. The cholesteric liquid crystals were incorporated into the networks. The free-standing films were obtained by the spin-coating method. In order to improve the compatibility and microstructure of the cholesteric liquid crystals with PVA/silica polymer networks, the amphiphilic compound of hexadecyl trimethyl ammonium bromide (HDTMA) was introduced into the forming film solutions. Effects of the different ratios of raw materials on the structure of films were investigated. The microscopic morphology of free-standing films and the uniform dispersion of CLCs in the films have been characterized by polarizing optical microscopy (POM), the field emission scanning electron microscope (FESEM), Fourier transform infrared (FT-IR) spectrometer and atomic force microscope (AFM). The free-standing films exhibiting excellent CLC droplets dispersion, mechanical stability, and good flexibility could be useful for flexible displays, switchable optical elements and smart windows. 相似文献
20.
B. Borak S. Laskowski O. Heczko A. Aaltonen A. Baszczuk M. Jasiorski O. Söderberg B. Mazurek M. Oja S.-P. Hannula K. Maruszewski 《Journal of Sol-Gel Science and Technology》2007,41(2):185-190
Magnetic powders based on metallic iron crystallites encapsulated in submicron-sized spherical silica particles have been obtained and investigated. The metallic iron clusters have been produced by the exploding wire method. The silica shells have been prepared via the modified sol-gel Stöber method and the metallic particles have been entrapped by occlusion during the silica powder formation. The entrapped iron particles are partially oxidized due to the nature of the synthetic methods employed. The obtained hybrid materials have been investigated by electron microscopy, X-ray diffraction, magnetic and ζ-potential techniques. Such materials can be employed in such applications as e.g. magnetically-controlled drug vectors or electromagnetic field-shielding. 相似文献