Sol-gel synthesis of silica–based mesoporous powders

2004 ◽  
Vol 848 ◽  
Author(s):  
Lidia Armelao ◽  
Gregorio Bottaro ◽  
Renzo Campostrini ◽  
Stefano Gialanella ◽  
Marco Ischia ◽  
...  
Keyword(s):  
Sol Gel ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structure Directing Agent ◽  
Template Removal ◽  
Guest Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Sol Gel Synthesis

ABSTRACTMesoporous silica powders have been synthesized starting from aqueous solutions of Si(OCH2CH3)4 (TEOS) under acidic conditions, using non-ionic alkyl poly(ethylene oxide) oligomer (Brij76) as a structure-directing agent. Template removal was performed by thermal treatment in air as well as by ethanol extraction. The annealing process (400 - 600°C) resulted in more efficient elimination of the organic molecules, thus yielding hexagonal (p6mm) mesopor-ous materials with pore volume and specific surface area ranging between 0.58 – 0.41 cm3/g and 900 – 700 m2/g, respectively. The systems were characterized by X-Ray Diffraction (XRD), N2 BET adsorption, Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). Particular attention was focused on the evolution of the system mesostructural and porous features as a function of the template removal procedure. The obtained mesoporous networks are suitable as matrices for the development of nanocomposite systems in which the dispersion or the growth of various guest species (clusters, molecules…) can be addressed into the host mesopores.

Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

2003 ◽  
Vol 68 (10) ◽  
pp. 2019-2031 ◽  
Author(s):  
Markéta Zukalová ◽  
Jiří Rathouský ◽  
Arnošt Zukal
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Sodium Metasilicate ◽  
Spherical Particles ◽  
Structure Directing Agent ◽  
Inorganic Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

Study of Pseudoboehmite Synthesis by Sol-Gel Process

2006 ◽  
Vol 45 ◽  
pp. 260-265 ◽  
Author(s):  
Antônio Hortêncio Munhoz Jr. ◽  
Leila Figueiredo de Miranda ◽  
G.N. Uehara
Keyword(s):  
Sol Gel ◽  
Thermo Gravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Sol Gel Process ◽  
Different Temperatures ◽  
Sol Gel Synthesis

A pseudoboehmite was obtained by sol-gel synthesis using aluminum nitrate as precursor. It was used a 2n full factorial design for studying the effect of the temperature of synthesis, the concentration of ammonium hydroxide, and the radiation dose in the product of sol-gel synthesis. The product of the synthesis was analyzed by scanning electron microscopy, x-ray diffraction of the product (after firing the pseudoboehmite at different temperatures), and it was also analyzed the temperature of endothermic and exothermic transformations using the thermo gravimetric analysis (TG) and differential scanning calorimetry (DSC). The X-ray diffraction data show that α-alumina was obtained at 1100o C.

scholarly journals Facile Sol-gel Synthesis of Porous Silicas Using Poly(propylene)imine Dendrimers as Templates

2000 ◽  
Vol 15 (8) ◽  
pp. 1842-1848 ◽  
Author(s):  
Gustavo Larsen ◽  
Edgar Lotero ◽  
Manuel Marquez
Keyword(s):  
Single Molecule ◽  
Sol Gel ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Template Removal ◽  
Synthesis Conditions ◽  
Transmission Electron ◽  
Argon Adsorption ◽  
Poly Propylene ◽  
Sol Gel Synthesis

Commercially available poly(propylene)imine (DAB-Am-32 and DAB-Am-64) dendrimers were used as single-molecule templates to tailor the porosity of silicas via a nonacidic sol-gel method. X-ray diffraction on both the as-prepared (oven-dried at 373 K) and the calcined (833 K) materials revealed that modest contraction took place on template removal and that the cavities created did not achieve three-dimensional ordering under the current synthesis conditions. Transmission electron microscopy of “Pt-stained” samples supported this picture. A modified Horvath–Kawazoe analysis of the argon adsorption isotherms indicated that DAB-Am-64 is a much more effective template than DAB-Am-32. Pyrolysis and oxidation protocols for template removal are also presented.

Poly(ethylene glycol) as structure directing agent in sol–gel synthesis of amorphous silica

2014 ◽  
Vol 190 ◽  
pp. 146-151 ◽  
Author(s):  
O.V. Gorbunova ◽  
O.N. Baklanova ◽  
T.I. Gulyaeva ◽  
M.V. Trenikhin ◽  
V.A. Drozdov
Keyword(s):  
Ethylene Glycol ◽  
Amorphous Silica ◽  
Sol Gel ◽  
Poly Ethylene Glycol ◽  
Structure Directing Agent ◽  
Poly Ethylene ◽  
Sol Gel Synthesis

scholarly journals Effects of Hydrothermal Treatment and Template Removal on the Adsorption and Structural Properties of SBA-16 Mesoporous Silica

2007 ◽  
Vol 25 (6) ◽  
pp. 439-449 ◽  
Author(s):  
Pasquale F. Fulvio ◽  
Bogna E. Grabicka ◽  
Rafal M. Grudzien ◽  
Mietek Jaroniec
Keyword(s):  
Ethylene Oxide ◽  
Structural Properties ◽  
Hydrothermal Treatment ◽  
High Surface ◽  
Pluronic F127 ◽  
Structure Directing Agent ◽  
Template Removal ◽  
Large Pore ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

The evolution of the adsorption and structural properties of large-pore SBA-16 silica samples was studied in relation to hydrothermal treatment and template removal procedures. These samples were synthesized using the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer Pluronic F127 as the structure-directing agent and tetraethyl orthosilicate as the silica source in the presence of hydrochloric acid (low concentration) and sodium chloride under various hydrothermal treatment conditions. The concomitant use of the recently reported two-step template removal procedure, which combines solvent extraction and low-temperature calcination, afforded the SBA-16 samples with large pore volumes, high surface areas, uniform cages and uniform cage openings as demonstrated by nitrogen and argon adsorption isotherms measured at −196°C. Small-angle X-ray diffraction spectra confirmed the existence of the Im3m symmetry group (body-centred cubic pore structure) for the samples studied. The efficiency of the aforementioned template removal method was confirmed via thermogravimetric analysis.

On the Properties of an Ion Conductive System Incorporated in Hybrid Films

2000 ◽  
Vol 628 ◽  
Author(s):  
G. González ◽  
P. J. Retuert ◽  
S. Fuentes
Keyword(s):  
Electrochemical Impedance ◽  
Ternary Phase Diagram ◽  
Lithium Perchlorate ◽  
Molar Ratio ◽  
Ionic Conductors ◽  
X Ray Diffraction ◽  
Poly Ethylene Oxide ◽  
Ion Conducting ◽  
Poly Ethylene ◽  
High Degree

ABSTRACTBlending the biopolymer chitosan (CHI) with poly (aminopropilsiloxane) oligomers (pAPS), and poly (ethylene oxide) (PEO) in the presence of lithium perchlorate lead to ion conducting products whose conductivity depends on the composition of the mixture. A ternary phase diagram for mixtures containing 0.2 M LiClO4 shows a zone in which the physical properties of the products - transparent, flexible, mechanically robust films - indicate a high degree of molecular compatibilization of the components. Comparison of these films with binary CHI-pAPS nanocomposites as well as the microscopic aspect, thermal behavior, and X-ray diffraction pattern of the product with the composition PEO/CHI/pAPS/LiClO4 1:0.5:0.6:0.2 molar ratio indicates that these films may be described as a layered nanocomposite. In this composite, lithium species coordinated by PEO and pAPS should be inserted into chitosan layers. Electrochemical impedance spectroscopy measurements indicate the films are pure ionic conductors with a maximal bulk conductivity of 1.7*10-5 Scm-1 at 40 °C and a sample-electrode interface capacitance of about 1.2*10-9 F.

scholarly journals Sodium Solid Electrolytes: NaxAlOy Bilayer-System Based on Macroporous Bulk Material and Dense Thin-Film

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 854
Author(s):  
Antonia Hoppe ◽  
Cornelius Dirksen ◽  
Karl Skadell ◽  
Michael Stelter ◽  
Matthias Schulz ◽  
...  
Keyword(s):  
Pore Size ◽  
Bulk Material ◽  
Sol Gel ◽  
Dense Layer ◽  
X Ray Diffraction ◽  
Bilayer System ◽  
Step Procedure ◽  
Short Circuits ◽  
Α Al2o3 ◽  
Sol Gel Synthesis

A new preparation concept of a partially porous solid-state bilayer electrolyte (BE) for high-temperature sodium-ion batteries has been developed. The porous layer provides mechanical strength and is infiltrated with liquid and highly conductive NaAlCl4 salt, while the dense layer prevents short circuits. Both layers consist, at least partially, of Na-β-alumina. The BEs are synthesized by a three-step procedure, including a sol-gel synthesis, the preparation of porous, calcined bulk material, and spin coating to deposit a dense layer. A detailed study is carried out to investigate the effect of polyethylene oxide (PEO) concentration on pore size and crystallization of the bulk material. The microstructure and crystallographic composition are verified for all steps via mercury intrusion, X-ray diffraction, and scanning electron microscopy. The porous bulk material exhibits an unprecedented open porosity for a NaxAlOy bilayer-system of ≤57% with a pore size of ≈200–300 nm and pore volume of ≤0.3 cm3∙g−1. It contains high shares of crystalline α-Al2O3 and Na-β-alumina. The BEs are characterized by impedance spectroscopy, which proved an increase of ionic conductivity with increasing porosity and increasing Na-β-alumina phase content in the bulk material. Ion conductivity of up to 0.10 S∙cm−1 at 300 °C is achieved.

scholarly journals V2O3/C composite fabricated by carboxylic acid-assisted sol–gel synthesis as anode material for lithium-ion batteries

2021 ◽  
Author(s):  
G. S. Zakharova ◽  
E. Thauer ◽  
A. N. Enyashin ◽  
L. F. Deeg ◽  
Q. Zhu ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Lithium Ion Batteries ◽  
Sol Gel ◽  
Carbon Sources ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Battery Electrode ◽  
Sol Gel Synthesis

AbstractThe potential battery electrode material V2O3/C has been prepared using a sol–gel thermolysis technique, employing vanadyl hydroxide as precursor and different organic acids as both chelating agents and carbon sources. Composition and morphology of resultant materials were characterized by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies, physical sorption, and elemental analysis. Stability and electronic properties of model composites with chemically and physically integrated carbon were studied by means of quantum-chemical calculations. All fabricated composites are hierarchically structured and consist of carbon-covered microparticles assembled of polyhedral V2O3 nanograins with intrusions of amorphous carbon at the grain boundaries. Such V2O3/C phase separation is thermodynamically favored while formation of vanadium (oxy)carbides or heavily doped V2O3 is highly unlikely. When used as anode for lithium-ion batteries, the nanocomposite V2O3/C fabricated with citric acid exhibits superior electrochemical performance with an excellent cycle stability and a specific charge capacity of 335 mAh g−1 in cycle 95 at 100 mA g−1. We also find that the used carbon source has only minor effects on the materials’ electrochemical performance.

scholarly journals Study Structure and Properties of Nanocomposite Material Based on Unsaturated Polyester with Clay Modified by Poly(ethylene oxide)

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Tran Duy Thanh ◽  
Nguyen Dang Mao ◽  
Nguyen Thi Kim Ngan ◽  
Ha Thuc Chi Nhan ◽  
Ha Thuc Huy ◽  
...  
Keyword(s):  
Ethylene Oxide ◽  
Polymer Matrix ◽  
Unsaturated Polyester ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Poly Ethylene Oxide ◽  
Hydrophobic Nature ◽  
Poly Ethylene ◽  
Alkyl Ammonium

In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide) was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, and make nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide), modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by X-ray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr.

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