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Author |
Cassiers, K.; van der Voort, P.; Linssen, T.; Vansant, E.F.; Lebedev, O.; van Landuyt, J. |
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Title |
A counterion-catalyzed (S0H+)(X-I+) pathway toward heat- and steam-stable mesostructured silica assembled from amines in acidic conditions |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical |
Abbreviated Journal |
J Phys Chem B |
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Volume |
107 |
Issue |
16 |
Pages |
3690-3696 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA) |
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Abstract |
An alternative pathway to assemble mesoporous molecular sieve silicas is developed using nonionic alkylamines and N,N-dimethylalkylamines (SO) as structure-directing agents in acidic conditions. The synthesized mesostructures possess wormhole-like frameworks with pore sizes and pore volumes in the range of 20-90 Angstrom and 0.5-1.3 cm(3)/g, respectively. The formation of the mesophase is controlled by a counterion-mediated mechanism of the type (S(0)H(+))(X(-)I(+)), where S(0)H(+) are protonated water molecules that are hydrogen bonded to the lone electron pairs on the amine surfactant headgroups (S(0)H(+)), X(-) is the counteranion originating from the acid, and I(+) are the positively charged (protonated) silicate species. We found that the stronger the ion X(-) is bonded to S(0)H(+), the more it catalyzes the silica condensation into (S(0)H(+))(X(-)I(+)). Br(-) is shown to be a strong binding anion and therefore a fast silica polymerization promoter compared to Cl(-) resulting in the formation of a higher quality mesophase for the Br(-) syntheses. We also showed that the polymerization rate of the silica, dictated by the counterion, controls the morphology of the mesostructures from nonuniform agglomerated blocks in the case of Br(-) syntheses to spherical particles for the Cl(-) syntheses. Next to many benefits such as low temperature, short synthesis time, and the use of inexpensive, nontoxic, and easily extractable amine templates, the developed materials have a remarkable higher thermal and hydrothermal stability compared to hexagonal mesoporous silica, which is also prepared with nonionic amines but formed through the S(0)I(0) mechanism. |
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Place of Publication |
Washington, D.C. |
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Wos |
000182350200005 |
Publication Date |
2003-04-17 |
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Series Issue |
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Edition |
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ISSN  |
1520-6106;1520-5207; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.177 |
Times cited |
9 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.177; 2003 IF: 3.679 |
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Call Number |
UA @ lucian @ c:irua:103300 |
Serial |
24 |
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Author |
Liu, S.; Cool, P.; Collart, O.; van der Voort, P.; Vansant, E.F.; Lebedev, O.I.; Van Tendeloo, G.; Jiang, M. |
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Title |
The influence of the alcohol concentration on the structural ordering of mesoporous silica: cosurfactant versus cosolvent |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
The journal of physical chemistry : B : condensed matter, materials, surfaces, interfaces and biophysical |
Abbreviated Journal |
J Phys Chem B |
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Volume |
107 |
Issue |
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Pages |
10405-10411 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA) |
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Place of Publication |
Washington, D.C. |
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Wos |
000185401900013 |
Publication Date |
2003-09-18 |
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Edition |
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ISSN |
1520-6106;1520-5207; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.177 |
Times cited |
134 |
Open Access |
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Notes |
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Approved |
Most recent IF: 3.177; 2003 IF: 3.679 |
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Call Number |
UA @ lucian @ c:irua:46264 |
Serial |
1643 |
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Author |
Colomer, J.-F.; Henrard, L.; Flahaut, E.; Van Tendeloo, G.; Lucas, A.A.; Lambin, P. |
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Title |
Rings of double-walled carbon nanotube bundles |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Nano letters |
Abbreviated Journal |
Nano Lett |
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Volume |
3 |
Issue |
5 |
Pages |
685-689 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
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Place of Publication |
Washington |
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Wos |
000183040100025 |
Publication Date |
2003-05-14 |
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ISSN |
1530-6984;1530-6992; |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
12.712 |
Times cited |
59 |
Open Access |
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Notes |
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Approved |
Most recent IF: 12.712; 2003 IF: 6.144 |
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Call Number |
UA @ lucian @ c:irua:54853 |
Serial |
2908 |
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Author |
van Renterghem, W.; Schryvers, D.; van Landuyt, J.; van Roost, C.; de Keyzer, R. |
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Title |
The influence of crystal thickness on the image tone |
Type |
A1 Journal article |
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Year |
2003 |
Publication |
Journal of imaging science |
Abbreviated Journal |
J Imaging Sci Techn |
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Volume |
47 |
Issue |
2 |
Pages |
133-138 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT) |
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Abstract |
It is known that the neutral image tone of a developed photographic film becomes brownish when the thickness of the original silver halide tabular crystals is reduced. We investigate by electron microscopy to what extent the silver filament structure has changed and how it induces the shift in image tone. Therefore, two samples of AgBr {111} tabular crystals with average thicknesses of 160 nm and 90 nm respectively, are compared. It is shown that the dimensions and defect structure of the filaments are comparable, but that the 90 nm crystals result in a more widely spaced structure, which explains the shift in image tone on a qualitative level. The influence of the addition of an image toner, i.e., phenylmercaptotetrazole, on the filament structure is also investigated. An even more open filament structure of longer, but smaller filaments was observed. |
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Place of Publication |
Springfield, Va |
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Wos |
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Publication Date |
0000-00-00 |
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Edition |
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ISSN |
8750-9237; 1062-3701 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
0.348 |
Times cited |
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Open Access |
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Notes |
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Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:48384 |
Serial |
1619 |
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