scholarly journals Nanostructured Mesoporous Silica Wires with Intrawire Lamellae via Evaporation-Induced Self-Assembly in Space-Confined Channels

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Michael Z. Hu ◽  
Donglu Shi ◽  
Douglas A. Blom
Keyword(s):  
Mesoporous Silica ◽  
Aging Time ◽  
Self Assembly ◽  
Water Solution ◽  
Sol Gel ◽  
Vacuum Impregnation ◽  
Anodized Aluminum ◽  
Structure Directing Agent ◽  
Evaporation Induced Self Assembly ◽  
Silica Precursor

Evaporation-induced self-assembly (EISA) of silica sol-gel ethanol-water solution mixtures with block-copolymer were studied inside uniform micro/nano-channels. Nanostructured mesoporous silica wires, with various intrawire self-assembly structures including lamellae, were prepared via EISA process but in space-confined channels with the diameter ranging from 50 nm to 200 nm. Membranes made of anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC) were utilized as the arrays of space-confined channels (i.e., 50, 100, and 200 nm EPC and 200 nm AAO) for infiltration and drying of mixture solutions; these substrate membranes were submerged in mixture solutions consisting of a silica precursor, a structure-directing agent, ethanol, and water. After the substrate channels were filled with the solution under vacuum impregnation, the membrane was removed from the solution and dried in air. The silica precursor used was tetraethyl othosilicate (TEOS), and the structure-directing agent employed was triblock copolymer Pluronic-123 (P123). It was found that the formation of the mesoporous nanostructures in silica wires within uniform channels were significantly affected by the synthesis conditions including (1) preassemble TEOS aging time, (2) the evaporation rate during the vacuum impregnation, and (3) the air-dry temperature. The obtained intrawire structures, including 2D hexagonal rods and lamellae, were studied by scanning transmission electron microscopy (STEM). A steric hindrance effect seems to explain well the observed polymer-silica mesophase formation tailored by TEOS aging time. The evaporation effect, air-drying effect, and AAO versus EPC substrate effect on the mesoporous structure of the formed silica wires were also presented and discussed.

scholarly journals Effect of boron incorporation on the bioactivity, structure, and mechanical properties of ordered mesoporous bioactive glasses

2020 ◽  
Vol 8 (7) ◽  
pp. 1456-1465 ◽  
Author(s):  
Leonie Deilmann ◽  
Oliver Winter ◽  
Bianca Cerrutti ◽  
Henrik Bradtmüller ◽  
Christopher Herzig ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Self Assembly ◽  
Sol Gel ◽  
Bioactive Glasses ◽  
Structure Directing Agent ◽  
Structural Investigations ◽  
Ordered Mesoporous ◽  
Evaporation Induced Self Assembly

B2O3 doped (0.5–15 mol%) ordered mesoporous bioactive glasses were synthesized via sol–gel based evaporation-induced self-assembly using P123 as a structure directing agent and characterized by biokinetic, mechanical and structural investigations.

Fabrication and characterization of mesoporous borosilicate glasses with different boron contents

2007 ◽  
Vol 22 (7) ◽  
pp. 1834-1838 ◽  
Author(s):  
Tongping Xiu ◽  
Qian Liu ◽  
Jiacheng Wang
Keyword(s):  
Boric Acid ◽  
Self Assembly ◽  
Sol Gel ◽  
Sorption Isotherms ◽  
Mesoporous Structure ◽  
Borosilicate Glasses ◽  
Whole Process ◽  
Transmission Electron ◽  
Evaporation Induced Self Assembly ◽  
The Stability

A series of wormhole-like mesoporous borosilicate glasses (MBSGs) with different compositions has been prepared by a combination of surfactant templating, sol-gel methods, and evaporation-induced self-assembly processes. Small-angle x-ray diffraction, high-resolution transmission electron microscopy, and N2 sorption isotherms analysis showed that all the MBSGs prepared possess the mesoporous structure. However, the stability of the mesoporous structure is strongly affected by the boron contents. When boron content was increased, boric acid was found in the final product, and the mesoporous structure was partially degraded. The formation and loss of boric acid through the whole process may account for the partial collapse of the mesostructure.

Synthesis and Characterization of Mesoporous Silica Nanoparticles Embedded Gadolinium Oxide

2011 ◽  
Vol 306-307 ◽  
pp. 1275-1279 ◽  
Author(s):  
Ning Qi Luo ◽  
Zhan Yun Huang ◽  
Ping Luo ◽  
Yuan Zhi Shao ◽  
Di Hu Chen
Keyword(s):  
Mesoporous Silica ◽  
Self Assembly ◽  
Mesoporous Silica Nanoparticles ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Gadolinium Oxide ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
The Mean

We first synthesized gadolinium oxide (Gd2O3) by a modified “polyol” strategy and then embedded it into mesoporous silica by a simple self-assembly sol-gel reaction. Scanning electron microscope (SEM) results show that the samples have good sphericity and good dispersibility. The structure of mesoporous silica was characterized by transmission electron microscopy (TEM) and small-angle X-ray diffraction (SAXRD). Results show that the mesoporous structure has not been destroyed after gadolinium oxide imbedding. The ratio of gadolinium and silica was determined by the mean of energy dispersive spectroscopy (EDS).

Catalytic Activity of Fe-SBA-15 Prepared by Evaporation-Induced Self-Assembly (EISA) Method

2017 ◽  
Vol 898 ◽  
pp. 1916-1922
Author(s):  
Tie Ming Zhang ◽  
De Yong Li ◽  
Wen Liu
Keyword(s):  
Catalytic Activity ◽  
Self Assembly ◽  
Cost Effective ◽  
Product Yield ◽  
Bet Surface Area ◽  
Phenol Hydroxylation ◽  
Structure Directing Agent ◽  
Pluronic P123 ◽  
Fe Content ◽  
Evaporation Induced Self Assembly

Fe-SBA-15 materials with different Fe content have been prepared using tetraethyl orthosilicate (TEOS) and iron nitrate (Fe (NO3)3·H2O as precursors and Pluronic P123 as structure directing agent through evaporation-induced self-assembly (EISA) method. The materials were characterized by nitrogen sorption, powder X-ray diffraction and TEM. All the Fe-SBA-15 samples appeared ordered 2D hexagonal mesostructure. The BET surface area and pore diameter were about 500 m2/g and 4 nm respectively. In the reaction of phenol hydroxylation to dihydroxybenzenes, the Fe-SBA-15 materials showed good catalytic activity, giving 20.2% of phenol conversion, 58.2% of selectivity for o-dihydroxy benzene and 41.8% of selectivity for p-dihydroxy benzene. After five cycles, the product yield was 25.2%, while selectivities of o-dihydroxy benzene and p-dihydroxy benzene were 58.2% and 41.8%, respectively. All these findings indicated the potential of Fe-SBA-15-10 could be used as a cost-effective, environment-friendly catalyst.

scholarly journals Hybrid mesoporous silica with controlled drug release

2019 ◽  
Vol 84 (9) ◽  
pp. 1027-1039 ◽  
Author(s):  
László Almásy ◽  
Ana-Maria Putz ◽  
Qiang Tian ◽  
Gennady Kopitsa ◽  
Tamara Khamova ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Drug Release ◽  
Mesoporous Silica ◽  
Drug Loading ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Controlled Drug Release ◽  
Ammonium Bromide ◽  
Structure Directing Agent ◽  
One Step

The mesoporous silica particles were prepared by the sol?gel method in one-step synthesis, in acidic conditions, from tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES), varying the mole ratio of the silica precursors. Nitric acid was used as catalyst at room temperature and hexadecyltrimethyl ammonium bromide (CTAB) as structure directing agent. Optical properties, porosity and microstructure of the materials in function of the MTES/TEOS ratio were evaluated using infrared spectroscopy, nitrogen adsorption and small angle X-ray scattering. All materials showed the ordered pore structure and the high specific surfaces, making them suitable as the drug delivery systems. Drug loading and release tests using ketoprofen were performed to assess their performance for drug delivery applications. The amount of the methylated precursor used in the synthesis had little effect on the drug loading capacity, but had a strong influence on the initial rate of the drug release.

Hierarchical Macro-Mesoporous Silica Monolith

2004 ◽  
Vol 847 ◽  
Author(s):  
Tomohiko Amatani ◽  
Kazuki Nakanishi ◽  
Kazuyuki Hirao ◽  
Tetsuya Kodaira
Keyword(s):  
Self Assembly ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Silica Gels ◽  
Polymerization Reaction ◽  
Structure Directing Agent ◽  
Swelling Agent ◽  
Pure Silica ◽  
Inorganic Species ◽  
Hexagonal Arrays

ABSTRACTMonolithic pure silica gels with hierarchical macro-mesoporous structure have been synthesized via spontaneous sol-gel process from silicon alkoxide using a structure-directing agent and a micelle-swelling agent. Monolithic body with well-defined co-continuous macropores is a result of concurrent phase separation and sol-gel transition induced by the polymerization reaction, whereas the mesopores are templated by the cooperative self-assembly of inorganic species, a structure-directing agent and a micelle-swelling agent. The following removal of surfactants by heat-treatment gives silica gels with hierarchical and fully accessible pores in discrete size ranges of micrometers and nanometers. The highly ordered 2D-hexagonal arrays of mesopores have been confirmed by X-ray diffraction measurements and FE-SEM observations. Furthermore, by further additions of the micelle-swelling agent, the mesostructural transition from well-ordered 2D-hexagonal arrays to mesostructured cellular foams (MCF) have been induced accompanied by minor modifications of the micrometer-range structure.

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