Silica-Cyclodextrin Hybrid Materials: Two Possible Synthesis Processes

Both cyclodextrin (CD) and porous silica possess interesting properties of adsorption and release. A silica-CD hybrid, therefore, could synergically merge the properties of the two components, giving rise to a material with appealing properties for both environmental and pharmaceutical applications. With this aim, in the present study, a first hybrid is obtained through one-pot sol-gel synthesis starting from CD and tetramethyl orthosilicate (TMOS) as a silica precursor. In particular, methyl-β-cyclodextrin (bMCD) is selected for this purpose. The obtained bMCD-silica hybrid is a dense material containing a considerable amount of bMCD (45 wt.%) in amorphous form and therefore represents a promising support. However, since a high specific surface area is desirable to increase the release/adsorption properties, an attempt is made to produce the hybrid material in the form of an aerogel. Both the synthesis of the gel and its drying in supercritical CO₂ are optimized in order to reach this goal. All the obtained samples are characterized in terms of their physico-chemical properties (infra-red spectroscopy, thermogravimetry) and structure (X-ray diffraction, electron microscopy) in order to investigate their composition and the interaction between the organic component (bMCD) and the inorganic one (silica).