Nanowires for surface enlargement of narrow‐bore fused‐silica tubing

Abstract

A method for preparation of silica nanowires with dimensions of d = 10-100 nm, l = 5-500 nm, is described. The nanostructured material is an integral part of the inner surface of narrow bore fused-silica capillary tubing. The wire preparation method is based on a decomposition of 2-chloro-1,1,2-trifluoroethyl methyl ether at elevated temperature and pressure. The silica bulk material is rearranged via a sustained silica-hydrogen fluoride chemistry, and reaction mechanisms for this process are proposed. The method is suitable for preparing long lengths of tubing with the modified surface. It is our belief that the texture of the capillary wall with its increased surface area is useful for applications such as microreactions, catalysis, and high-resolution pressure and/or electrodriven open-tubular liquid chromatography.

Near- and Supercritical Water as a Diameter Manipulation and Surface Roughening Agent in Fused Silica Capillaries

“…Several reviews are available of the large field of FSC surface modification and/or roughening procedures; − during the last two decades, the majority of FSC surface treatment applications have shifted from chromatographic to electromigration methods. To name but a few agents used for treatment of the inner surfaces of FSCs, one should mention, e.g., microcrystalline NaCl layer to facilitate coating FSCs with ionic liquids, ammonium hydrogen difluoride for FSC applications in electrochromatography, application of Grignard agents to chlorinated surface silanols to form Si–C bonds on the inner surface of FSC, or 2-chloro-1,1,2-trifluoroethyl methyl ether used to prepare nanowires inside narrow-bore FSCs, , apart from the age-long application of concentrated aqueous solution of sodium hydroxide to etch the glass or silica surfaces. The latter procedure has also been used in modifications involving the use of potassium hydroxide instead of NaOH and the use of methanol as a solvent instead of water …”