| Autor: |
Wu, Qing, Rankin, Stephen |
| Zdroj: |
Journal of Sol-Gel Science & Technology; Oct2011, Vol. 60 Issue 1, p81-90, 10p |
| Abstrakt: |
Porous titania thin films with well-ordered mesostructures are prepared by using Pluronic surfactant P123 as the pore template and aging the films in a high-humidity environment at −6 °C. These structures are stable enough to undergo calcination at 400 °C to generate nanocrystalline TiO walls with retention of mesoporosity. Under the aging conditions used, the films have well-ordered mesostructures even with a molar ratio of P123 to titanium ( R) as small as 0.006. Because the P123 micelle diameter remains constant across a range of compositions, the pore diameter also remains fixed but the wall thickness of the titania thin films increases as the P123 concentration decreases without decreasing the long-range order of the products. Furthermore, mesoporous titania thin films with hexagonal close-packed channels oriented perpendicular to the substrate can be obtained R values of 0.008-0.012 by sandwiching the as-prepared films between glass slides modified with crosslinked P123. Analysis of the mesophases obtained here indicates that a transition from films containing significant 2D hexagonal channels to 3D hexagonal structure occurs below P123/Ti = 0.008. This does not match the expected volume fraction for this transition based on the mesophases behavior of aqueous P123 at room temperature, suggesting that a more detailed model would be needed to predict mesostructure in titania films aged below the freezing point of water. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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