Synthesis of hexagonal mesoporous silicates functionalized with amino groups in the pore channels by a co-condensation approach

RSC Advances ◽  
2016 ◽  
Vol 6 (59) ◽  
pp. 53991-54000 ◽  
Author(s):  
Yunping Li ◽  
Wei Xiong ◽  
Chun Wang ◽  
Bo Song ◽  
Guolin Zhang
Keyword(s):  
Triblock Copolymer ◽  
Sol Gel ◽  
Amino Groups ◽  
Mesoporous Silicates ◽  
Sol Gel Process ◽  
Acidic Conditions

Mesoporous silicates functionalized with amino groups in the pore channels have been made by the co-condensation of tetraethoxyl siloxide (TEOS) with precursors of P–Si through a triblock copolymer-templated sol–gel process under acidic conditions.

Enhanced tribological properties of bismaleimides with a novel hybrid silicon dioxide containing amino groups

2020 ◽  
Vol 32 (10) ◽  
pp. 1150-1159
Author(s):  
Yuan Jia ◽  
Juxiang Yang ◽  
Xue Hu ◽  
Zhen Liu
Keyword(s):  
Silicon Dioxide ◽  
Tribological Properties ◽  
Sol Gel ◽  
Amino Groups ◽  
Silicon Dioxide Nanoparticles ◽  
Friction Process ◽  
Excessive Heat ◽  
Sol Gel Process ◽  
Volume Wear ◽  
Hybrid Silicon

To improve the tribological properties of bismaleimide (BMI) resin, silicon dioxide nanoparticles with imino and terminal functional amino groups were prepared through a sol–gel process to form a novel SiO2-NH2 hybrid. The as-prepared hybrid was then applied as a modifying agent for the BMI matrix to obtain SiO2-NH2/BMI composites. Compared to those of pure BMI resin, the volume wear rate and friction coefficient of the SiO2-NH2/BMI composites decreased significantly, while the wear mechanism changed from fatigue (BMI) to adhesive (SiO2-NH2/BMI) wear. This improvement in the tribological properties of the SiO2-NH2/BMI composites was attributed to the appropriate SiO2-NH2 added content, which endowed the BMI with excellent mechanical and thermal-resistant properties. Thus, the SiO2-NH2/BMI composites could resist the external load and excessive heat during the friction process.

scholarly journals PVP-Stabilized Palladium Nanoparticles in Silica as Effective Catalysts for Hydrogenation Reactions

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Caroline Pires Ruas ◽  
Daiane Kessler Fischer ◽  
Marcos Alexandre Gelesky
Keyword(s):  
Catalytic Activity ◽  
Palladium Nanoparticles ◽  
Sol Gel ◽  
Molar Ratio ◽  
Sol Gel Process ◽  
Hydrogenation Reactions ◽  
Acidic Conditions

Palladium nanoparticles stabilized by poly (N-vinyl-2-pyrrolidone) (PVP) can be synthesized by corresponding Pd(acac)2(acac = acetylacetonate) as precursor in methanol at 80°C for 2 h followed by reduction with NaBH4and immobilized onto SiO2prepared by sol-gel process under acidic conditions (HF or HCl). The PVP/Pd molar ratio is set to 6. The effect of the sol-gel catalyst on the silica morphology and texture and on Pd(0) content was investigated. The catalysts prepared (ca.2% Pd(0)/SiO2/HF andca.0,3% Pd(0)/SiO2/HCl) were characterized by TEM, FAAS, and SEM-EDS. Palladium nanoparticles supported in silica with a size 6.6 ± 1.4 nm were obtained. The catalytic activity was tested in hydrogenation of alkenes.

Preparation of Pt Nanoparticles Dispersed in Mesoporous Silica

2009 ◽  
Vol 1217 ◽  
Author(s):  
Yukitoshi Chiba ◽  
Hirobumi Shibata ◽  
Daichi Nagata ◽  
Takahiro Gunji ◽  
Ryuji Tamura ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Platinum Nanoparticles ◽  
Triblock Copolymer ◽  
Sol Gel ◽  
Pt Nanoparticles ◽  
Chelating Agent ◽  
Pluronic P123 ◽  
Amphiphilic Triblock Copolymer ◽  
Sol Gel Process ◽  
Phenanthroline Complex

AbstractPlatinum nanoparticles were dispersed in mesopores of mesoporous silica using a sol-gel process with a composite template consisting of an amphiphilic triblock copolymer (Pluronic P123 or F127) and a Pt-organic complex, which was prepared with K2Pt(II)Cl4 as a Pt source and 1,10-phenanthroline as a chelating agent. The obtained Pt-1,10-phenanthroline complex did not dissolve in any of several solvents, e.g., hexane, benzene, toluene, THF, H2O, CH3OH, and C2H5OH. However, when the Pt-1,10-phenanthroline complex was reacted with ethylenediamine it dissolved in many solvents. Platinum nanoparticles dispersed in mesoporous silica were obtained using a sol-gel process with a complex template consisting of Pt-1,10-phenanthroline-ethylenediamine, and an amphiphilic triblock copolymer (Pluronic P123 or F127). A sample dried at 353 K was bright yellow. When it was subsequently heat-treated at 823 K, it turned light gray. This change indicates that Pt nanoparticles can be obtained by heat-treatment at high temperature, because, to generate Pt nanoparticles, the organics chelated to Pt ions must be removed. Measurements from small-angle x-ray scattering show that mesoporous silica obtained using a complex template has a much more highly ordered pore structure than that obtained using only an amphiphilic triblock copolymer. It has both large pores (above 8 nm) and a large surface area (about 290 m2/g). Furthermore, results of a TEM investigation showed that Pt nanoparticles were generated only in mesopores of mesoporous silica.

scholarly journals Ionic Liquids/SiO2 Supporting Pd Nanoparticles: Efficient Catalysts in Hydrogenation Reaction

2021 ◽  
pp. 8-12
Author(s):  
Hartz Taís ◽  
Fischer Daiane ◽  
Karina de Fraga ◽  
Scheeren Carla
Keyword(s):  
Ionic Liquids ◽  
Palladium Nanoparticles ◽  
Sol Gel ◽  
Pd Nanoparticles ◽  
Hydrogenation Reaction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Sol Gel Process ◽  
Acidic Conditions ◽  
Palladium Content

Palladium nanoparticles (ca. 4.8 nm) were synthesized in presence of 1-n-butyl-3-methylimidazolium tetraflouroborate (BMI.BF4) and 1-n-butyl-3-methylimidazolium hexafluorophosphate (BMI.PF6) and PMI.Si.(OMe)3.Cl functionalized ionic liquids using the sol-gel method. The characteristics of the sol-gel method, ionic liquid on the palladium content was studied, as well as the silica morphology and texture of the support and the hydrogenation activity. The palladium content in the resulting xerogels (ca. 0.22 wt% Pd/SiO2) was shown to be independent of the sol-gel process. The xerogels synthesized in acidic conditions formed materials with larger pore diameters, which in turn might be responsible for the higher catalytic activity in hydrogenation of the alkenes and arenes obtained with the heterogeneous catalyst (Pd/ILs/SiO2).

Study on the Sol-Gel Process of TEOS by React-IR

2011 ◽  
Vol 110-116 ◽  
pp. 1401-1405 ◽  
Author(s):  
Hua Hua Zhou ◽  
Wei Xue ◽  
Fang Li ◽  
Yan Fei Qin
Keyword(s):  
Sol Gel ◽  
Porous Silica ◽  
Polymerization Rate ◽  
Condensation Polymerization ◽  
Acid Base ◽  
Nucleophilic Reaction ◽  
Sol Gel Process ◽  
Acidic Conditions ◽  
Adsorption Desorption ◽  
Meso Scale

Porous silica was prepared through TEOS sol-gel process catalyzed by acid-base joint catalyst, and the process was monitored by React IRTM. Based on the measurements, mechanism of TEOS hydrolyzation and succedent condensation polymerization was inferred. Under acidic conditions, H+ attacks –OR group of TEOS firstly, then the electronegative Cl- can attack Si4+ and make TEOS be hydrolyzed. When basic catalyst was added, the reaction will be accelerated. The promotion effect of base is attributed to the direct nucleophilic reaction mechanism and the smaller size of OH-, which can attack Si more easily. Thirdly, silanol, generated from TEOS hydrolyzation, attract Si-OR or other Si-OH around; thereby resulting rapid dehydration or de-alcohol reaction. So the condensation polymerization rate is elevated, and Si-O-Si bond comes into being. Lastly, cross-linking reaction among Si-O-Si bonds forms the particle like conglomeration. The porous silica was characterized by SEM and N2 adsorption-desorption technique. It was shown that the silica had large specific surface area, 818.5 m2/g, and relatively narrow distribution of pore size in meso-scale. Futhermore, the mesopores were nonuniform in shape and arrangement.

Fabrication of Hollow Porous Silica Using a Combined Emulsion Sol–Gel Process and Amphiphilic Triblock Copolymer for Loading of Quercetin

2015 ◽  
Vol 15 (10) ◽  
pp. 7935-7941 ◽  
Author(s):  
Sang Gil Lee ◽  
Young Ho Kim ◽  
Jun Tae Bae ◽  
Chung Hee Lee ◽  
Hyeong Bae Pyo ◽  
...  
Keyword(s):  
Triblock Copolymer ◽  
High Performance ◽  
Sol Gel ◽  
Porous Silica ◽  
Poloxamer 407 ◽  
Bet Surface Area ◽  
Silica Spheres ◽  
Cell Protection ◽  
Sol Gel Process ◽  
The Stability

Flavonoids have recently attracted significant interest as potential reducing agents, hydrogendonating antioxidants, and singlet oxygen-quenchers. Quercetin, in particular, induces the expression of a gene, known to be associated with cell protection, in dose- and time-dependent manners. Therefore, quercetin may be used as an effective cosmeceutical material useful in the protection of dermal skin. In this study, hollow porous silica spheres used to load quercetin were prepared by using a combined emulsion sol–gel process and triblock copolymer as a template. Fabrication of hollow porous silica spheres was performed under various conditions such as the molar ratios of H2O/TEOS (w) and weight ratios of poloxamer 184/poloxamer 407. Loading of quercetin in hollow porous silica spheres was devised to improve the stability of quercetin and to consider the possibility as a raw cosmetic material. The surface of inclusion complexes of quercetin in hollow porous silicas was modified to enhance the stability of quercetin. The physicochemical properties of the samples were investigated using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA)-differential thermal analysis (DTA) and Brunauer–Emmett–Teller (BET) surface area and porosity analysis. Determination of quercetin concentration was carried out by high-performance liquid chromatography (HPLC) analysis.

Spontaneous solution-sol-gel process for preparing tin oxide monolith

1996 ◽  
Vol 11 (4) ◽  
pp. 813-820 ◽  
Author(s):  
Nae-Lih Wu ◽  
Lih-Fu Wu ◽  
Ya-Chin Yang ◽  
Shu-Jiuan Huang
Keyword(s):  
Gas Sensing ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Tin Chloride ◽  
Sol Gel Process ◽  
New Process ◽  
Ethanol Addition ◽  
Acidic Conditions ◽  
Increasing Temperature ◽  
Solution Acidity

A sol-gel process for preparing SnO2 monolith of high specific surface area and transparency from chloride solution is described. Without introducing any alkaline precipitating reagent to induce condensation, this new process employs tin chloride (or its hydrate), water, and, optionally, alcohols as the only process reagents. Spontaneous solution-to-sol and sol-to-gel transitions take place upon mixing these reagents under appropriate conditions, and the entire transition processes are carried out under acidic conditions (typically pH ≤ 4.0). The rate of condensation has been found to increase with decreasing SnCl4 concentration, which corresponds to decreasing solution acidity, and with increasing temperature. For fixed starting salt concentration and temperature, there exists an optimum amount of ethanol addition for the fastest condensation. Good performance of thus derived SnO2 monolith has been demonstrated in two applications, including catalytic oxidation and solid-state gas-sensing for carbon monoxide.

The crystallization of thin-film ceramics

1992 ◽  
Vol 50 (1) ◽  
pp. 338-339
Author(s):  
J.M. Schwartz ◽  
L.F. Francis ◽  
L.D. Schmidt ◽  
P.S. Schabes-Retchkiman
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Sol Gel ◽  
Processing Route ◽  
Small Areas ◽  
Ceramic Thin Films ◽  
Complex Shapes ◽  
Sol Gel Process ◽  
Ceramic Precursors ◽  
Crystalline Ceramic

Ceramic thin films and coatings are of interest for electrical, optical, magnetic and thermal barrier applications. Critical for improved properties in thin films is the development of specific microstructures during processing. To this end, the sol-gel method is advantageous as a versatile processing route. The sol-gel process involves depositing a solution containing metalorganic or colloidal ceramic precursors onto a substrate and heating the deposited layer to form a crystalline or non-crystalline ceramic coating. This route has several advantages, including the ability to create tailored microstructures and properties, to coat large or small areas, simple or complex shapes, and to more easily prepare multicomponent ceramics. Sol-gel derived coatings are amorphous in the as-deposited state and develop their crystalline structure and microstructure during heat-treatment. We are particularly interested in studying the amorphous to crystalline transformation, because many key features of the microstructure such as grain size and grain size distribution may be linked to this transformation.

Epitaxial Growth of Sr0.3Ba0.7Nb2O6 Thin Films Prepared by Sol-Gel Process

1999 ◽  
Vol 606 ◽  
Author(s):  
Keishi Nishio ◽  
Jirawat Thongrueng ◽  
Yuichi Watanabe ◽  
Toshio Tsuchiya
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Epitaxial Growth ◽  
Raw Materials ◽  
Substrate Surface ◽  
Sol Gel ◽  
Tungsten Bronze ◽  
Monomethyl Ether ◽  
Tetragonal Tungsten Bronze ◽  
Sol Gel Process

AbstructWe succeeded in the preparation of strontium-barium niobate (Sr0.3Ba0.7Nb2O6 : SBN30)that have a tetragonal tungsten bronze type structure thin films on SrTiO3 (100), STO, or La doped SrTiO3 (100), LSTO, single crystal substrates by a spin coating process. LSTO substrate can be used for electrode. A homogeneous coating solution was prepared with Sr and Ba acetates and Nb(OEt)5 as raw materials, and acetic acid and diethylene glycol monomethyl ether as solvents. The coating thin films were sintered at temperature from 700 to 1000°C for 10 min in air. It was confirmed that the thin films on STO substrate sintered above 700°C were in the epitaxial growth because the 16 diffraction spots were observed on the pole figure using (121) reflection. The <130> and <310> direction of the thin film on STO were oriented with the c-axis in parallel to the substrate surface. However, the diffraction spots of thin film on LSTO substrate sintered at 700°C were corresponds to the expected pattern for (110).

UV Curable Organic-Inorganic Hybrid Materials

2000 ◽  
Vol 628 ◽  
Author(s):  
Guang-Way Jang ◽  
Ren-Jye Wu ◽  
Yuung-Ching Sheen ◽  
Ya-Hui Lin ◽  
Chi-Jung Chang
Keyword(s):  
Hybrid Materials ◽  
Colloidal Silica ◽  
Sol Gel ◽  
Solution Ph ◽  
Uv Curable ◽  
Inorganic Hybrid ◽  
Degradation Temperature ◽  
Sol Gel Process ◽  
The Stability ◽  
Thermal Degradation Temperature

This work successfully prepared an UV curable organic-inorganic hybrid material consisting of organic modified colloidal silica. Applications of UV curable organic-inorganic hybrid materials include abrasion resistant coatings, photo-patternable thin films and waveguides. Colloidal silica containing reactive functional groups were also prepared by reacting organic silane and tetraethyl orthosilicate (TEOS) using sol-gel process. In addition, the efficiency of grafting organic moiety onto silica nanoparticles was investigated by applying TGA and FTIR techniques. Experimental results indicated a strong interdependence between surface modification efficiency and solution pH. Acrylate-SiO2 hybrid formation could result in a shifting of thermal degradation temperature of organic component from about 200°C to near 400°C. In addition, the stability of organic modified colloidal silica in UV curable formula and the physical properties of resulting coatings were discussed. Furthermore, the morphology of organic modified colloidal silica was investigated by performing TEM and SEM studies‥

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