Anionic templated mesoporous silica

The AMS (anionic surfactant-templated mesoporous silicas) materi-aisi30,i40,i42 family of well-ordered organosilicas prepared using anionic... 

T. (2003) Synthesis of anionic-surfectant-templated mesoporous silica using organoalkoxysilane-containing amino groups. Chem, Mater., 15 (24), 4536-4538 (b) Che, S., Liu, Z Ohsuna, T., Sakamoto, K Terasaki, 0 and Tatsumi, T. (2004) Synthesis and characterization of chiral mesoporous silica. Nature, 429 (6989), 281-284. 

Scheme 16.6 Ionic interactions between anionic surfactant and cationic costructuredirecting agent (CSDA) in the synthesis of anionic surfactant template mesoporous silica (AMS). (Adapted from Ref. [100].)...

Figure 1. Scheme for the liquid crystalline templating mechanism proposed by Kresge et al 1 for synthesis of mesoporous silica MCM-41. Formation of a hexagonal array of cylindrical micelles possibly mediated by silicate anions followed by condensation of the silicate anions from the silicate source (tetraethylorthosilicate) leads to templated framework structure. Calcination or extraction of the template produces hexagonally ordered mesoporous silica. 

In basic solution (pH >10), the silicate ion is anionic. The simplest method is the use of a cation template (e.g., cationic surfactant) to organize these silicate ions. This interaction (synthesis pathway), S I, was applied in the classical synthesis of mesoporous silica in basic media. 

S. Che, A.E. Garcia-Bennett, T. Yokoi, K. Sakamoto, H. Kunieda, O. Terasaki, and T. Tatsumi, A Novel Anionic Surfactant Templating Route for Synthesizing Mesoporous Silica with Unique Structure. Nature Mater. (London), 2003, 2, 801-805. 

O., and Tatsumi, T. (2003) A novel anionic surfactant templating route for synthesizing mesoporous silica with unique structure. Nat. Mater., 2, 801-805. 

In general, the procedures used for the preparation of mesoporous materials are similar to those utilized in the synthesis of zeolites except that a surfactant instead of an inorganic cation or base is used as the template. Mesoporous materials (e.g., mesoporous silica) are prepared under room temperature or mild hydrothermal conditions (typically below 150°C) in the presence of anionic, cationic, or neutral surfactants, in either basic or acidic conditions. 

Che, S., Garcia-Bennett, A.E., Yokoi, T., Sakamoto, K., Kunieda, H., Terasaki, O., and Tatsumi, T. (2003) A novel anionic surfactant templating route for synthesizing mesoporous silica with unique structure. Nat. Mater., 2 (12), 801-805. 

Figure 11.5 TEM images of hollow mesoporous silica particles prepared using an anionic PS template (A40-an, A30-an, and A5-an) and the cationic PS template (A25-cat). Scale bar 100 nm. (Reproduced with permission from Ref. [37], Copyright 2008, American Chemical Society.)...

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