Synthesis of silica xerogels with highly distinct morphologies in the presence of imidazolium ionic liquids

• Published in: Journal of sol-gel science and technology 2009, Vol.49 (1), p.71-77
• Main Authors: Donato, R. K., Migliorini, M. V., Benvegnú, M. A., Stracke, M. P., Gelesky, M. A., Pavan, F. A., Schrekker, C. M. L., Benvenutti, E. V., Dupont, J., Schrekker, H. S.
• Format: Article
• Language: English
• Subjects: Anions; Atomic force microscopy; Catalysis; Ceramics; Chemical bonds; Chemistry; Chemistry and Materials Science; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Exact sciences and technology; Flat surfaces; General and physical chemistry; Glass; Hydrofluoric acid; Inorganic Chemistry; Ionic liquids; Ions; Materials Science; Microscopy; Morphology; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper; Photography; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Porcelain; Scanning electron microscopy; Silicon dioxide; Sol-gel processes; Spherical powders; Tetraethyl orthosilicate; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Thermogravimetric analysis; X-ray diffraction; Xerogels
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-008-1829-6

This article describes the preparation of silica xerogels by the sol–gel technique, using tetraethoxysilane as precursor and hydrofluoric acid as catalyst, in the presence of imidazolium ionic liquids (ILs). The applied ILs 1 – 3 contained the 1-monoethylene glycol monomethyl ether-3-methylimidazolium cation in combination with the methanesulfonate ( 1 ), tetrafluoroborate ( 2 ) and hexafluorophosphate ( 3 ) anions, respectively. Characterization of these materials was performed by photography, scanning electron microscopy, atomic force microscopy, X-ray diffraction, thermogravimetric analysis and nitrogen adsorption-desorption isotherms. The IL anion was identified as a powerful morphology controller. The methanesulfonate anion of IL 1 induced the formation of a compact lamellar monolith with an interlamellar distance of 1.5 nm and a flat surface. A free flowing powder of aggregated spherical particles was obtained in the presence of tetrafluoroborate IL 2 , and the hexafluorophosphate anion of IL 3 induced the formation of porcelain like aggregates with honeycomb shapes.