Octadecyl trimethylammonium bromide

Phenylene-bridged periodic mesoporous organosilicas, with both amorphous and crystal-like walls, (referred to in the following as AW-Ph-HMM and CW-Ph-HMM, respectively) were synthesized and characterized as previously reported [6,7]. BTEB was used as a precursor for both solids the surfactant was Brij-76 (Ci8H37(OCH2CH2)nOH) in acidic media for AW-Ph-HMM and octadecyl-trimethylammonium bromide(ODTMA) in basic media for CW-Ph-HMM. A purely siliceous MCM-41 sample was also synthesised, the first step being the solution of octadecyltrimethylammonium bromide in a basic aqueous solution (NH3), kept a 333 K. Tetraethyl orthosilicate (TEOS) was then added in all cases dropwise, and the mixture stirred for 24h at room temperature (H20 34.2 g/ NH3 (15%) 8.52 g/ ODTMA 0.73 g TEOS 3.24 g). After further 24 hours in hydrothermal conditions at 368 K, the sample... 

Then, two MCM-41 materials modified by octyl-dimethyl chlorosilanes were tested. The parent MCM-41 matrices were synthesized by conventional route using hexadecyl-trimethylammonium bromide (sample MTS2) and octadecyl-trimethylammonium bromide (sample MTSl). They exhibit typical peaks of hexagonal ordered mesoporous materials in X-ray diffraction patterns. 

Octadecyl trimethylammonium bromide (stearyl trimethylammonum bromide)720-02-77 M... 

We describe in a companion paper (33) the salient features of our procedures for measuring low surface pressures, and we provide n-A isotherms for octadecyl trimethylammonium bromide (Ci8 TAB) and sodium octadecyl sulfate (Ci8 sulfate) monolayers spread at A/W and O/W interfaces. Here we extend some of these data to higher A using, in some instances, some of our earlier reported measurements. We have also taken from literature the few reported isotherms for dilute charged monolayers and discuss them in the light of our results and the predictions of Equations 7 and 8. 

The simplest, and at the same time the most effective way to achieve dispersion in water or aqueous media is the addition of amphiphihc molecules carbon nanotubes without any functional groups are hydrophobic. This characteristic may be employed to enclose them in micelles. The surfactant molecules arrange around the single tubes with their hydrophilic head directed outward and their hydrophobic tail oriented toward the nanotube in the center. In this manner, each individual tube is surrounded by an envelop that enables a dispersion, for example, in water. Yet complete solubilization requires considerable amounts of the surfactant. Solutions obtained this way may in fact contain up to 80% of detergent and only 20% of carbon nanotubes. Surfactants suitable to enclose nanotubes in micelles include, for example, sodium dodecylsulfate (SDS), Triton X-100, or octadecyl-trimethylammonium bromide (OTAB). 

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