Type

Journal Article

Authors

Justin D. Holmes
Ralf Schweins
Richard K Heenan
David C Steytler
Michael A. Morris
Trevor R Spalding
Kirk J Ziegler
Mark P Copley
John P Hanrahan

Subjects

Chemistry

Topics
surface properties x ray diffraction carbon dioxide chemistry nitrogen phase transition adsorption magnesium hydroxide surface active agents aluminum hydroxide porosity silicon dioxide hydrotalcite microscopy electron transmission

Pore size engineering in mesoporous silicas using supercritical CO2. (2005)

Abstract In this paper we investigate the use of supercritical carbon dioxide (sc-CO(2)) for synthesizing calcined mesoporous silicas with tunable pore sizes, wall thickness, and d spacings. Small angle neutron scattering was used to probe the controlled swelling of the triblock copolymer surfactant templating agents, P123 (PEO(20)PPO(69)PEO(20)), P85 (PEO(26)PPO(39)PEO(26)), and F127 (PEO(106)PPO(70)PEO(106)), as a function of CO(2) pressure. The transition from the liquid crystal phase to the calcined mesoporous silicas, formed upon condensation and drying, was also studied in detail. Powder X-ray diffraction, transmission electron microscopy, and nitrogen adsorption techniques were used to establish pore diameters, silica wall widths, and the hexagonal packing of the pores within the calcined silicas. Using a direct templating method, the diameters of mesopores and the spacing between the pores could be tuned with a high level of precision. The swelling process was observed to have no detrimental effects on the quality of silica formed, a distinct advantage over conventional swelling techniques, and all of the silicas synthesized in this study were highly ordered over distances of at least 2000 A.
Collections Ireland -> University College Cork -> PubMed

Full list of authors on original publication

Justin D. Holmes, Ralf Schweins, Richard K Heenan, David C Steytler, Michael A. Morris, Trevor R Spalding, Kirk J Ziegler, Mark P Copley, John P Hanrahan

Experts in our system

1
Justin D. Holmes
University College Cork
Total Publications: 287
 
2
Michael A. Morris
University College Cork
Total Publications: 164