Journal article
Pore size engineering in fluorinated surfactant templated mesoporous silica powders through supercritical carbon dioxide processing
Microporous and mesoporous materials, Vol.113(1), pp.106-113
2008
DOI: 10.1016/j.micromeso.2007.11.017
Abstract
Pore expansion of fluorinated surfactant templated mesoporous silica powders is demonstrated as a function of pressurized CO
2 processing conditions. Mesoporous silica powder is synthesized by sol–gel reaction induced precipitation in a base-catalyzed medium using 1-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-octyl)-pyridinium chloride (HFOPC) as a template and, immediately after filtration, the precipitated material is processed in gaseous and supercritical CO
2 (88–344
bar, 45
°C) for 48
h. Characterization of the silica powders by XRD, TEM and N
2 adsorption reveals the formation of well-ordered materials with 2D hexagonal close-packed pore structure before and after CO
2 processing. An optimal aging time (time from addition of silica precursor to the sol until the filtration of the hydrolyzed sol) of 20
min prior to CO
2 processing is identified. Proper aging time results in silica powder with significant pore expansion at all processing pressures while retaining the long-range structure of the material. The pore diameter of the mesoporous material increases with increasing CO
2 pressure (from 2.60
nm (unprocessed) to 3.21
nm at 344
bar), but appears to level off above 100
bar. The pore expansion behavior is attributed to favorable CO
2 penetration in the ‘CO
2-philic’ fluorinated tails of the surfactant template. The CO
2 expansion of base-catalyzed silica powders is significantly less than we previously observed for acid catalyzed, evaporation-driven thin film synthesis using fluorinated cationic surfactant templates. The effect of pH on self-assembly and increased silica condensation in basic conditions may inhibit pore expansion by CO
2.
Details
- Title: Subtitle
- Pore size engineering in fluorinated surfactant templated mesoporous silica powders through supercritical carbon dioxide processing
- Creators
- Kaustav Ghosh - Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-0046, United StatesSarah Bashadi - Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-0046, United StatesHans-Joachim Lehmler - Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA 52242-5000, United StatesStephen E Rankin - Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-0046, United StatesBarbara L Knutson - Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506-0046, United States
- Resource Type
- Journal article
- Publication Details
- Microporous and mesoporous materials, Vol.113(1), pp.106-113
- DOI
- 10.1016/j.micromeso.2007.11.017
- ISSN
- 1387-1811
- eISSN
- 1873-3093
- Publisher
- Elsevier Inc
- Language
- English
- Date published
- 2008
- Academic Unit
- Occupational and Environmental Health; Iowa Neuroscience Institute
- Record Identifier
- 9984001092402771
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