This work was partially supported by the CICYT, Spain (Projects: MAT2000-0096-P4-02, MAT2003-06003-C02-01, and BTE2003-05757-C02-02). We are indebted to Dr. M. Yates for fruitful discussions on the textural analyses of samples. We also thank Mr. F. Pinto for technical assistance in TEM, SEM, and EDAX studies, as well as Mr. T. García-Somolinos for his help in the surface area determinations. Supporting Information is available online from Wiley InterScience or from the author.
A Colloidal Route for Delamination of Layered Solids: Novel Porous-Clay Nanocomposites†
Article first published online: 8 DEC 2005
Copyright © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Advanced Functional Materials
Volume 16, Issue 3, pages 401–409, February, 2006
How to Cite
Letaïef, S., Martín-Luengo, M. A., Aranda, P. and Ruiz-Hitzky, E. (2006), A Colloidal Route for Delamination of Layered Solids: Novel Porous-Clay Nanocomposites. Adv. Funct. Mater., 16: 401–409. doi: 10.1002/adfm.200500190
- Issue published online: 27 JAN 2006
- Article first published online: 8 DEC 2005
- Manuscript Accepted: 4 JUL 2005
- Manuscript Received: 4 APR 2005
- Nanocomposites, inorganic;
- Sol–gel processes
Under soft conditions, it is possible to cause the irreversible delamination of organoclays (long-chain alkylammonium cation-exchanged smectites, and vermiculite-layered silicate derivatives) via a sol–gel process that involves alkoxysilanes (e.g., tetraethoxysilane) and that finally gives silica–clay heteromaterials. These intermediate silica–organoclay nanocomposites facilitate the diffusion of the alkoxides which, in the presence of water, are hydrolyzed and subsequently polymerized. This process is a heterocoagulation that gives homogeneous gels in which the order in the layer stacking of clays is partially or completely lost, depending on the nature of the layered silicate. After calcination to eliminate the organic moiety, that is, the alkylammonium chains, the gel is irreversibly transformed into a silica–clay material in which the silicate layers are fully separated by the silica network generated by the alkoxide. The resulting solids are inorganic–inorganic nanocomposites which could be compared to polymer–clay nanocomposites, but in the present case the inorganic silica network is the continuous phase and the individual layers the corresponding disperse phase of the nanocomposite. These materials are solids of high specific surface area (> 400 m2 g–1), which exhibit micro- and mesoporosity, and also have properties inherent to both components, the pristine clay (e.g., a cation-exchange capacity) and the silica network (e.g., an ability to be functionalized).