Surfactants CTAC cetyltrimethylammonium chloride

In micelles of the surfactant cetyltrimethylammonium chloride (CTAC), the ratio of AA AB BB is <1 >98 <1 %. The CTAC micelles provide a cage effect, which greatly enhances the joining of the A and B radicals produced by the photolysis (Scheme 12.3). 

Preparing mixture solution A Distilled H20, NaOH and surfactant (cetyltrimethylammonium chloride, CTAC) were mixed together with stirring, then adding alumina source (if synthesis of Zr (Ti)-Si-Al material, here adding alumina source + Zr (Ti)... 

Fig. 7. Molecular structure of the spin probe 4-(A, A -dimethyl-A -hexadecyl)-ammonium-2,2,6,6-tetramethyl piperidinyloxy iodide (CAT16) and the surfactant cetyltrimethylammonium chloride (CTAC).

Goldfarb et al. (65) discovered how to monitor the synthesis of MCM-41 in the liquid/solid phase by EPR spectroscopy using a nitroxide radical, 4-(A, A -dimethyl-A -hexadecyl)-ammonium-2,2,6,6-tetramethyl piperidinyloxy iodide (CAT16), as probe molecule. This nitroxide has a structure similar to that of cetyltrimethylammonium chloride (CTAC), which was used as surfactant in the synthesis of MCM-41 (Fig. 7). Thus, it was shown to be the best suited to monitor the formation process of MCM-41. Because the synthesis was performed at room temperature, commercial flat cells could be used for EPR measurements without the need for further heating. 

FT-EPR spectra of the ZnTPPS/DQ system in a solution of cetyltrimethylammonium chloride (CTAC), a cationic surfactant, are shown in figure B 1.16.21. As in the TXlOO solution, both donor and acceptor are... 

The general features of micelles and reversed micelles (polar head buried in, with the hydrophilic tail pointing out to a low dielectric medium) can enhance the separation of photoproducts in different fashions. One of the best known examples is the effect of the surfactant cetyltrimethylammonium chloride (CTAC) on the photoreduction of by... 

The shape and size of self-assembled micellar systems depend on the conditions for a given system. Changes can be induced, e.g., by addition of cosurfactant or salt or by high surfactant concentrations. An aqueous solution of cetyltrimethylammonium chloride (CTAC) exhibits a transition from spherical micelles to elongated cylinders upon addition of chlorate anions, which is shown, for instance, by a strong increase in viscosity [25]. This system was experimentally studied by TRLQ, with results in good agreement with theory, as shown in Fig. 4. 

Anions will be separated by cationic micellar phases. Kirkbright and Mullins obtained the elution order T> N03 > Br > N02 > lOj with a 0.14 M cetyltrimethylammonium chloride (CTAC) micellar mobile phase and a C18 Spherisorb column [29]. This is the usual eluotropic order obtained with strong basic anion exclmngers. They showed that the ion retention decreased with the increase of both the ionic strength, p, and the surfactant concentration. Plots of 1/k vs. and 1/k vs. [CTAC] were linear. The first linear relationship is typical of ion-exchange mechanisms, the second plot means that the anion-micelle interaction obeys the Armstrong-Nome model for molecule-micelle partition. 

Cationic sm-factants such as tetradecyltrimethyl-ammonium bromide (TTAB), cetyltrimethylammoni-um bromide (CTAB), and cetyltrimethylammonium chloride (CTAC) have also been useful for MEKC analysis. Most cationic sm-factants have an alkyltri-methylammonium group, and their counterions are halides. The addition of cationic surfactants to the backgroimd electrolytes (BGE) caused the reversal of electroosmotic flow (EOF) owing to a positively charged capillary wall on account of the adsorption of cationic sm-factants. As a result of the reversed EOF, the polarity of the electrodes has to be reversed in order to detect the analytes. 

A low concentration of an ionic surfactant in the capillary electrolyte can also be used to modify the migration behavior of sample ions. A cationic surfactant such as cetyltrimethylammonium chloride (CTAC) is often used for anion separations, and SDS is often used when cations are to be separated. Kenata et al. [11] found that CTAC decreased the effective electrophoretic mobilities of several inorganic anions as the result of two processes ... 

More recent studies of amine adsorption mechanisms at surfaces have been carried out using atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), and SFVS techniques (Bakshi et al. 2004 Castro et al. 1986 C hemyshova et al. 2000 Fuerstenau and Renhe 2004 Paruchuri et al. 2004 Schrodle and Richmond 2008 Subramanian and Ducker 2000 Velegol et al. 2000). AFM studies show that spherical micelles of cetyltrimethylammonium bromide/cetyltrimethylammonium chloride (CTAB/CTAC) surfactants form at silica surfaces near the critical micelle concentration (CMC) (Bakshi et al. 2004). Compared with tertiary and quaternary amines, primary amines, such as DDA, would have a different molecular structure at the silica surface. For example, AFM studies suggest that primary amine forms a featureless bilayer at mica surfaces. 

Most MLC procedures use micelles of the anionic surfactant sodium dodecyl sulfate (SDS). Other useful surfactants include the cationic cetyltrimethylammonium bromide or chloride (CTAB or CTAC) and the nonionic Brij-35. The separations are usually carried out in Cig or Cg columns. 

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