Silica dodecyltrimethylammonium bromide

Presented below is an example of structure development at the solid-liquid interface for the silica/dodecyltrimethylammonium bromide (C12TAB) system, at pH 4.0 and O.IM NaCl as the background electrolyte, obtained by Singh et aL (11). A combination of different techniques such as adsorption, zeta potential, contact angle and FT-IR attenuated total reflection (ATR) measurements, have been used in this study to clearly illustrate the structural transitions, and the structure of self-assembled surfactant films at different adsorbed amounts of the surfactants at the interface. 

Periodic mesoporous vanadium modified silicates (V-MCM-41 and V-HMS) were synthesized, characterized and tested in our laboratory [93,141,172-174], V-MCM-41 samples were prepared hydrotheimally at 373 K using Cab-O-Sil fumed silica, vanadyl sulfate and dodecyltrimethylammonium bromide [172]. The preparation of V-HMS was carried out at room temperature in the presence of dodecylamine as template [173,174]. 

Microporous solid selected in this study is alumina pillared montmorillonite (Al-PILM) which exhibits well-defined slit-shaped micropores. Four mesoporous solids are examined Two silica MCM-41 samples prepared with quaternary ammonium surfactants dodecyltrimethylammonium bromide (the main carbon chain of the ammonium has 12 carbon atoms. Cl2) and cetyltrimethylammonium bromide. They are labeled as MCM-41 (Cl2) and MCM-41 (Cl6), respectively. The other two are commercial porous silicas (Kieselgel 60 and silica gel 40 A from Aldrich). 

The adsorption of dodecyltrimethylammonium bromide (LNBr) from aqueous solutions on silica and glass slides dewetted by these solutions was measured by using molecules labeled with radioisotopes (C and Br At low LNBr concentrations the counterion, Br , was not adsorbed. It was assumed that the ions were chemisorbed by cation... 

When brought in contact with aqueous solutions of organic salts (dodecyltrimethylammonium bromide [3] or dodecylammonium chloride [19]) of increasing concentrations, the surface electric charge of silica may decrease to zero and even become positive. 

Since then, the dewetting of silica has been extensively studied with solutions of dodecyltrimethylammonium bromide in the presence of HCl and NaOH, as well as the adsorption, 6 g of the dewetting agent at the surface of dewetted vitreous silica. 

Lokar, W. J. and Ducker, W. A. 2002. Proximal adsorption of dodecyltrimethylammonium bromide to the silica-electrolyte solution interface, Langmuir 18, 3167-3175. 

Kovacs-Hadady (1995) studied the retention behavior of barbiturates by overpressurized liquid chromatography (OPLC) on silica gel layers impregnated with paraffin or dodecyltrimethylammonium bromide and developed with mixtures of methanol and water. 

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