ANYL 141 |
| Ordered mesoporous silica films were synthesized by the selective condensation of tetraethylorthosilicate (TEOS) within amphiphilic templates using carbon dioxide as a heterogeneous reaction media. Blends of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (Pluronic F108) and poly(p-hydroxystyrene) (PHOSt) containing p-toluenesulfonic acid were exposed to gaseous or supercritical fluid solutions of CO2, TEOS and H2O. The morphology of the mesoporous silica can be tailored through the CO2 pressure during reaction. The pore radius increases slightly as the CO2 pressure is increased to approximately 80 bar. A small increase in pressure resulted in more than doubling of the pore size near 84 bar. The pore size then actually decreased slightly as the pressure was further increased. We attribute this maximum to anomalous swelling of the interface near the critical point similar to observations for swelling of thin polymer films. The impact of CO2 pressure on other physical properties of the films will also be discussed. |
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Nanomaterials in Analytical Chemistry
8:25 AM-12:25 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. 335, Oral
Division of Analytical Chemistry |