Preparation of Hard Mesoporous Silica Spheres

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Original entry: Ian Bruce Burgess Fall 2009


References

Q. Huo, J. Feng, F. Schuth, G.D. Stucky, Chemistry of Materials 9, 14-17 (1997).

Summary

This paper describes the synthesis of small spheres (0.1-2mm in diameter) made of a mesoporous silica from a surfactant-stabilized emulsion chemistry. What is remarkable about this technique is that the spheres, with hierarchical, levels of ordering on multiple length scales, are synthesized in a one step process. The spheres are synthesized as follows: The silicon ester tetrabutyl orthosilicate (TBOS, <math>Si(OC_{4}H_{9})_{4}</math>) is used as both the silica precursor and the organic phase in a slightly basic aqueous emulsion. The surfactant, cetyltetramethylammonium bromide, serves a dual purpose. It acts as a stabilizer for the emulsion, whose droplet size determines the size of the spheres, and forms nanoscale micelles in the organic phase which template the final porous structure. The TBOS reacts with water molecules (catalyzed in basic conditions) forming silica with butanol acting as the leaving group.

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