Brij surfactants

In addition to catalysis of small molecule transformations and biocatalysis, non-functionalized LLC phases used as reaction media have also been found to accelerate polymerization reactions as well. For example, the L and Hi phases of the sodium dodecylsulfate/n-pentanol/sulfuric acid system have been found to lower the electric potential needed to electropolymerize aniline to form the conducting polymer, polyaniline [110]. In this system, it was also found that the catalytic efficiency of the L phase was superior to that of the Hi phase. In addition to this work, the Ii, Hi, Qi, and L phases of non-charged Brij surfactants (i.e., oligo(ethylene oxide)-alkyl ether surfactants) have been observed to accelerate the rate of photo-initiated radical polymerization of acrylate monomers dissolved in the hydrophobic domains [111, 112]. The extent of polymerization rate acceleration was found to depend on the geometry of the LLC phase in these systems. Collectively, this body of work on catalysis with non-functionalized LLC phases indicates that LLC phase geometry and system composition have a large influence on reaction rate. 

Brij surfactants) (Fig. 18). Additionally, LLC phases of commercially available ionic surfactants such as metal salts of alkylsulfonic and alkylcarboxylic acids [e.g., dioctyl sodium sulfosuccinate (aka, Aerosol OT)] and long-chain ammonium salts have also been explored (Fig. 19). Some of these surfactants are even U.S. Food and Drug Administration (FDA)-approved because of their prior utility in other food or medication-related formulations. 

Liquids to waxy solids. Compds with one to five moles ethylene oxide are so] in oil and many hydrocarbons. Water soly increases with increasing ethylene oxide content. Properties of Brij surfactants G. King, Drug Cosmet. Ind. 90, 24 (1962). 

However, more details would be desirable. It is possible to express the architecture of an amphiphilic molecule by the number of units in the molecular chain. For instance, would denote the number of CH2 atoms, and AI7J would denote the number of ethylene oxide units in so-called Brij surfactants (see Fig. 2f). It is then possible to relate the size of the pores to the molecular architecture of the template molecules for a row of compositions (see Fig. 2g). Interestingly, the pore size depends on the size of both blocks. Classically (Fig. 3b), a microphase separation of the hydrophilic parts and hydrophobic parts into separate domains is expected. In this case, the pore-size dependence on both molecular parts is impossible. A "one-phase" scenario as depicted in Fig. 3a can also be excluded due to many reasons, which will not be further discussed here. ... 

Figure 11.8 Removal rates and Si02-to-poly-Si selectivity as a function of HLB value of the added Brij surfactant (a) Si02 and poly-Si removal rate dependency on the HLB value (b) Si02 and poly-Si selectivity dependency on the 1/HLB value.

Evidence of decreased solubility of both chlorhexidine diacetate and chlor-hexidine dihydrochloride in Brij surfactant mixtures has been adduced [203] though this is only clear in the case of the dihydrochloride at concentrations higher than 5% when uptake is some 30% higher in Brij 96 than in Brij 92-96 mixtures if HLB =11. 

As mentioned above, several types of PMO were synthesized using different templates and different reaction conditions. So, surfactant molecules are an important factor for the synthesis of PMOs and their numerous apphcations. The surfactants employed can be divided as shown in Figure 3.8. Ionic surfactants generally include C12-C18 alkyl chains with trimethylammonium head groups such as CTAB and octadecyltrimethylammonium chloride (OTAC). Nonionic surfactants consist of alkyl polyether type molecules such the Brij surfactants and the triblock copolymers such as Pluronic PI23 and FI27. 

It was found that the effect of solvents and various surfactants Triton X-100, Twin-80, Brij-35 sodium laurylsulfate, sodium cetylsulfate, cetylpyridinium chloride, cetyltrimethylammonium bromide on the luminescence intensity is insignificant. 

Some groups of pollutants also have specific problems. For instance, PAHs tend to adsorb on the walls of the system with which they come into contact and so an organic solvent or surfactant must be added to the sample. Several solvents have been tested (66, 67) isopropanol or acetonitrile are the most often used solvents, while Brij is the most recommended surfactant (66). A very critical parameter in these cases is their concentration. 

In addition, water motion has been investigated in reverse micelles formed with the nonionic surfactants Triton X-100 and Brij-30 by Pant and Levinger [41]. As in the AOT reverse micelles, the water motion is substantially reduced in the nonionic reverse micelles as compared to bulk water dynamics with three solvation components observed. These three relaxation times are attributed to bulklike water, bound water, and strongly bound water motion. Interestingly, the overall solvation dynamics of water inside Triton X-100 reverse micelles is slower than the dynamics inside the Brij-30 or AOT reverse micelles, while the water motion inside the Brij-30 reverse micelles is relatively faster than AOT reverse micelles. This work also investigated the solvation dynamics of liquid tri(ethylene glycol) monoethyl ether (TGE) with different concentrations of water. Three relaxation time scales were also observed with subpicosecond, picosecond, and subnanosecond time constants. These time components were attributed to the damped solvent motion, seg-... 

EOF reversal Surfactants SDS, CTAB, Brij, Tween, quaternary amines, diaminopropane, diaminobutane, Polybrene ... 

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... 

FIGURE 13.5 AFM images of Prussian blue-modified monocrystalline graphite (a) conventional Prussian blue deposited without surfactants, (b) Prussian blue electrochemically deposited through liquid crystalline phase of non-ionic surfactant Brij-56. 

Other cationic surfactants such as TTAB, DTAB, DODAB, STAC, CEDAB, and DDDAB have been used in CL reactions with less frequency. Thus, tetradecyltrimethylammonium bromide [TTAB] has been used to increase the sensitivity of the method to determine Fe(II) and total Fe based on the catalytic action of Fe(II) in the oxidation of luminol with hydrogen peroxide in an alkaline medium [47], While other surfactants such as HTAB, hexadecylpiridinium bromide (HPB), Brij-35, and SDS do not enhance the CL intensity, TTAB shows a maximum enhancement at a concentration of 2.7 X 10 2 M (Fig. 11). At the same time it was found that the catalytic effect of Fe(II) is extremely efficient in the presence of citric acid. With regard to the mechanism of the reaction, it is thought that Fe(II) forms an anionic complex with citric acid, being later concentrated on the surface of the TTAB cationic micelle. The complex reacts with the hydrogen peroxide to form hydroxy radical or superoxide ion on the... 

One of the nonionic surfactants most used as an enhancer of chemiluminescent reactions is Brij-35. This surfactant increases the reaction of lucigenin with catecholamines by a factor of 2.6 compared with the CL intensity in an aqueous medium [42], This enhancement can be explained in the following way it is known that oxygen from the polyoxyethylene chains in Brij-35 can react with sodium ion to form an oxonium ion, by which means the polyoxyethylene chains act as an oxonium cation. In this way the increase in CL intensity due to Brij-35 can be attributed to the same effect described for the micelles of a cationic surfactant. 

Dan et al. found that Brij-35 also produces an enhancement of the CL intensity of the reaction of fti.v AL[2-(A, -rnclhyl-2 -pyridiniumyl)ethyl]-AL [(trifluoromethyl)sulfonyl]]oxamide with hydrogen peroxide in the presence of some fluorophors [40], To be precise, the CL intensity increased by a factor of 130 for 8-aniline-1-naphthalenesulfonic acid (ANS) and 5.6 forrhodamine B (RH B), compared to the CL intensity in the absence of surfactant. This leads to an increase of 2-3 orders of magnitude in the linear dynamic ranges and a more precise determination of these analytes. However, improvement of the detection... 

When the influence was studied of different surfactants on the CL intensity of the reaction of lucigenin with isoprenaline, it was found that while cationic surfactants such as HTAH and HTAB and anionic surfactants such as SDS decrease the CL signal, the presence of Brij-35 increases the signal by a factor of 2.1 compared to that obtained in an aqueous medium [61]. As a result, a quite sensitive analytical method has been established for determination of isoprenaline, using Brij-35 as a CL enhancer. Application of the method has been satisfactorily verified with the determination of isoprenaline in pharmaceutical preparations. 

Figure 9.4. Characterization of mesoporous Si02 films with cylindrical mesopores (ca. 3nm in diameter) templated using Brij 58 surfactant TEM image a), 2D GISAXS pattern with crystallographic indexation b), and SRSAXS/XRR analysis c).The experimental data in c) thus correspond to a detailed scan along the sz axis in b), using a suitable diffractometer. The films were prepared according to Ref. 39 and analyzed by the methods described therein.

The AE blend Brij 35 with the general formula CnH2n+i 0(CH2CH20)mH was analysed by MALDI MS prior to use for biochemistry research. Separation results of thin-layer (TLC) and RP-LC of these surfactants were compared [30]. Brij 35, as a mixture of Ci2 and C14 homologues (to = 15-39), was detected qualitatively as [M + Na]+ and [M + K]+ ions and quantitatively after TLC and RP-LC separation. 

Aranda and Burk [81] have established an SPME-HPLC-FL method and on-line derivatisation to determine AEs (Brij 56) in water. The surfactant was extracted with a PDMS-DVB fibre and pre-column derivatisation with 1-naphthoyl chloride in the presence of 4-(dimethyl-amino)pyridine as catalyst. The method has a limit of detection of 0.1 mg L-1. 

Other commonly used surfactants are cetyltrimethylammonium bromide (CTAB), Brij, Tween, Triton X and Siloxane polyether copolymer (PSPEO) [53]. 

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