Aqueous stability of mesoporous silica films doped or grafted with aluminum oxide.
- University of New Mexico, Albuquerque, NM
Surfactant-templated silica thin films are potentially important materials for applications such as chemical sensing. However, a serious limitation for their use in aqueous environments is their poor hydrolytic stability. One convenient method of increasing the resistance of mesoporous silica to water degradation is addition of alumina, either doped into the pore walls during material synthesis or grafted onto the pore surface of preformed mesophases. Here, we compare these two routes to Al-modified mesoporous silica with respect to their effectiveness in decreasing the solubility of thin mesoporous silicate films. Direct synthesis of templated silica films prepared with Al/Si = 1:50 was found to limit film degradation, as measured by changes in film thickness, to less than 15% at near-neutral pH over a 1 week period. In addition to suppressing film dissolution, addition of Al can also cause structural changes in silica films templated with the nonionic surfactant Brij 56 (C{sub 16}H{sub 33}(OCH{sub 2}CH{sub 2}){sub n{approx}10}OH), including mesophase transformation, a decrease in accessible porosity, and an increase in structural disorder. The solubility behavior of films is also sensitive to their particular mesophase, with 3D phases (cubic, disordered) possessing less internal but more thickness stability than 2D phases (hexagonal), as determined with ellipsometric measurements. Finally, grafting of Al species onto the surface of surfactant-templated silica films also significantly increases aqueous stability, although to a lesser extent than the direct synthesis route.
- Research Organization:
- Sandia National Laboratories
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1005029
- Report Number(s):
- SAND2003-3187J
- Journal Information:
- Proposed for publication in LANGMUIR., Journal Name: Proposed for publication in LANGMUIR. Journal Issue: 24 Vol. 19; ISSN LANGD5; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
Similar Records
Nanoengineered Electrochemical Sensor Based on Mesoporous Silica Thin-film Functionalized with Thiol-Terminated Monolayer
Method for making surfactant-templated thin films