CTAB cetyl trimethyl ammonium bromide

Surfactants employed for w/o-ME formation, listed in Table 1, are more lipophilic than those employed in aqueous systems, e.g., for micelles or oil-in-water emulsions, having a hydrophilic-lipophilic balance (HLB) value of around 8-11 [4-40]. The most commonly employed surfactant for w/o-ME formation is Aerosol-OT, or AOT [sodium bis(2-ethylhexyl) sulfosuccinate], containing an anionic sulfonate headgroup and two hydrocarbon tails. Common cationic surfactants, such as cetyl trimethyl ammonium bromide (CTAB) and trioctylmethyl ammonium bromide (TOMAC), have also fulfilled this purpose however, cosurfactants (e.g., fatty alcohols, such as 1-butanol or 1-octanol) must be added for a monophasic w/o-ME (Winsor IV) system to occur. Nonionic and mixed ionic-nonionic surfactant systems have received a great deal of attention recently because they are more biocompatible and they promote less inactivation of biomolecules compared to ionic surfactants. Surfactants with two or more hydrophobic tail groups of different lengths frequently form w/o-MEs more readily than one-tailed surfactants without the requirement of cosurfactant, perhaps because of their wedge-shaped molecular structure [17,41]. 

Cetyl trimethyl ammonium bromide [CTAB]/w-alkanol [13-15]... 

Surface-active agents used as adjuvants in pharmaceutical preparations to improve drug dissolution may affect the stability of /3-lactams. Thus, the presence of micelles of cetyl(trimethyl)ammonium bromide (CTAB) enhanced up to 50-fold the rate of alkaline hydrolysis of penicillins [140]. In the case of cephalosporins, micelle-promoted catalysis of the intramolecular degradation process (see Sect 5.2.2) was also observed [85][141], It has been proposed that the negatively charged penicillins and cephalosporins are attracted by the cationic micelles. This attraction increases substrate concentration in the micellar phase, in turn accelerating the rate of HO- ion attack. Ion exchange at the micellar surface and electrostatic stabilization of the transition state may also contribute to the increased rate [142][143],... 

Surfactants such as cetyl trimethyl ammonium bromide (CTAB), Triton X-100 (TX-lOO) and sodium dodecyl sulphate (SDS) are the most commonly used. CTAB forms large micelles [24-26] with aggregation number 61, cmc 9.2 X 10 M, and a positive micellar Stem layer TX-lOO has aggregation number 139 with neutral OH groups on the Stern layer, and SDS forms negative micelles with cmc 8.3 x 10 M and aggregation number 131. The... 

Schultz and Matijevic (16) prepared nanoparticles of palladium sulfide (PdS) by the continuous double-jet mixing of PdCl2 or Na2(PdCl4) and Na2S. They found that the particle size was 20-30 nm in mean diameter obtained in acidic media (pH = 2-3), but 2-5 nm in alkaline media, probably due to the high equilibrium concentration of sulfide ions S2- by dissociation of H2S and HS in the alkaline media (pH = 10-12). A cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), was found to be useful for stabilizing the small particles prepared in alkaline media. 

Baxendale, Evans and coworkers reported in 1946 that the polymerization of methyl methacrylate (MMA) in aqueous solution was characterized by homogeneous solution kinetics, i.e. where mutual termination of free radicals occurred, in spite of the fact that the polymer precipitated as a separate phase. Increases in the rates of polymerization upon the addition of the surfactant cetyl trimethyl ammonium bromide (CTAB) were attributed to the retardation of the rate of coagulation of particles, which was manifested in a reduction in the effective rate constant for mutual termination,... 

In this area, recent unrelated efforts of the groups of Bhattacharya and Fife toward the development of new aggregate and polymer-based DAAP catalysts deserve mention. Bhattacharya and Snehalatha [22] report the micellar catalysis in mixtures of cetyl trimethyl ammonium bromide (CTAB) with synthetic anionic, cationic, nonionic, and zwitterionic 4,4 -(dialkylamino)pyridine functional surfactant systems, lb-c and 2a-b. Mixed micelles of these functional surfactants in CTAB effectively catalyze cleavage of various alkanoate and phosphotriester substrates. Interestingly these catalysts also conform to the Michaelis-Menten model often used to characterize the efficiency of natural enzymes. These systems also demonstrate superior catalytic activity as compared to the ones previously developed by Katritzky and co-workers (3 and 4). 

Eliasson and Ljunger (33) reported that the cationic surfactant cetyl trimethyl-ammonium bromide (CTAB) slowed down the rate of formation of amylopectin crystallites in gelatinized waxy maize starch, as measured by differential scanning calorimetry (DSC). 

Fig. 1. 1H chemical-shift dependence on the concentration of surfactants, Triton X-100 (TX-100) and cetyl trimethyl ammonium bromide (CTAB). 

Chemicals. N,N-dimethyldodecylamine-N-oxide (DDAO) and cetyl trimethyl-ammonium bromide (CTAB) were purchased from Fluka Chemical Corp. Cetyl pyridinium chloride (CPC) and polyoxyethylene nonyl phenyl ether, with an average degree of polymerization of 10 (NP(EO)2q) were obtained from Hexacel Corp. and... 

Competitive displacement of spread (3-lactoglobulin from an air-water interface by (a) nonionic and (b) ionic surfactants. The collapse of the protein network is indicated by showing the change in area occupied by the protein at the interface as a function of surface pressure, (a) Data for A-Tween 20 (polyoxyethylene sorbitan monolaurate) and B-Tween 60 (polyoxyethylene sorbitan momostearate). (b) Data for A-cetyl-trimethyl-ammonium bromide (CTAB), B-lyso-phosphatidylcholinelauroyl (LPC-L), and -sodium dodecyl sulphate (SDS). 

AFM images showing the displacement of a spread (3-lactoglobulin protein film from an air-water interface by the progressive addition of surfactant, (a) Displacement with (polyoxyethylene sorbitan monolaurate) Tween 20, surface pressure Tr=22.5mN/m, image size 3.2 X 3.2 jam. (b) Displacement with cetyl-trimethyl-ammonium bromide (CTAB), TT = 22.8 mN/m, image size 1x1 /rm. (c) Displacement with CTAB in the presence of 0.2 M sodium phosphate buffer, pH — 7, ir— 22.8 mN/m. scan size 1x1 /rm. Data are shown at similar surface pressures in order to allow comparison of domain sizes for ionic and nonionic surfactants. 

Hunter and Nicol [5] studied the flocculation and restabilisation of kaolinite suspensions using rheology and zeta-potential measurements. Figure 21.11 shows plots of the yield value (cr ) and electrophoretic mobility (i) as a function of cetyl trimethyl ammonium bromide (CTAB) concentration at pH =9. increases in line with increases in CTAB concentration, reaching a maximum at the point where the mobility reaches zero (the isoelectric point, i.e.p., of the clay), and then decreases with further increases in CTAB concentration. This trend can be explained on the basis of flocculation and restabilisation of the clay suspension. 

The location occupied by a solute within a micelle depends upon the structure and hydrophobicity of the solute as well as the charge of both the surfactant and the solute (Mittal K.L., 1977). A solute bearing a charge may associate tightly to an oppositely charged micelle surface, be confined to a region close to the surface, or exist in the bulk phase. A neutral solute may be solubilized within the micelle interior, close to the surface, in the surface, or on the surface. For those solutes with dimensions that are comparable to that of the micelles, a specific micellar location may not exist. However, two operational positions may be defined (a) within the micelle or close the surface and (b) on the surface, in close proximity to the aqueous bulk phase. Thomas J.K. (1980), for example, suggested that several aromatic molecules are solubilized on, or at the surface of cetyl trimethyl ammonium bromide (CTAB) micelles. 

Cationic Cetyl trimethyl ammonium bromide [CTAB]/w-alkanol w-Benzyl-w-dodecyl-w-bis(2-hydroxyethyl) ammonium chloride [BDB AC]/1 -hexanol [13-15] [16]... 

In this research, cetyl trimethyl ammonium bromide (CTAB), as an arrtimicrobial ent is applied on polyester, polypropylene and viscose non-woven fabrics alone and in combination with a Fluorochemical (FC 1112). The antimicrobial, water and blood repellency of the treated samples were investigated. To reveal the antimicrobial properties of the treated samples, the zone of inhibition and reduction of bacteria were measured with S. aureus, E. coli and P. aeroginosa. The results showed a good antimicrobial property on different concentration of CTAB solutions (1%, 2%, 4% and 8%). Application of CTAB with concentration of (0.5%, 1% and 2%) on polyester, polypropylene and viscose nonwoven fabrics indicated a reasonable antimicrobial effect Co-application of CTAB with fluorochemical on different samples also showed a good antimicrobial, water and blood repellency properties. 

The polypropylene and polyester melt blown and raw and dyed (direct) viscose nonwoven furies, cetyl trimethyl ammonium bromide (CTAB) as an antimicrobial finish agent (Fig.l), citric acid (5%), and fluorochemical namely FC 1112 (Organic Kimia Co.) as a water and blood repellents were used. 

Cetyl trimethyl ammonium bromide (CTAB). This has a greater space requirement than nitrogen and the CTAB number most closely approaches the determination of geometrical surface area (the surface without pores), correlating well with primary particle size. 

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