Functionalized surfactant

The chemical stability of Toyopearl HW-40 resin to organic eluents allows this material to be used for a variety of applications, including the purification of synthetic functionalized surfactants, polyphenolics, and phenolic glycosides (50,51). 

Nanocrystals are fabricated by using reverse micelles. Functionalized surfactants are employed. 

The longtime stabihty of surfactant-coated Pd nanoparticles in w/o microemulsions has been investigated. It has been proven that under suitable conditions, the use of the functionalized surfactant Pd(AOT)2 allows very stable nanosize Pd particles to be obtained and to finely control their average size [229],... 

Fig. 4.19 Preparation of a protein-like structure in an inorganic mesostructured framework (Proteosilica) as a transparent film using polypeptide-functionalized surfactants.

The first example of this type of reaction was provided by Kunitake and coworkers who found that deacylation ofp-nitrophenyl acetate by functional surfactants containing oximate or hydroxamate groups was strongly accelerated by tri-n-octylmethylammonium chloride (Okahata et al., 1977). 

C16H33NMe2CH2CH2OH Br, aq.NaOH, octane, t-amyl alcohol. Reaction involves phosphorylation of the functional surfactant... 

Deacylation of p-nitrophenyl esters of amino acids Synthetic vesicles + histidine-functionalized surfactant. Cholesterol increased rates and enantioselectivity Ueoka and Matsumoto, 1984... 

Comicelles of hydroxy-, phenol-, thiophenoxide-, thiol- and imidazole-functionalized surfactants. Rate comparisons... 

Comicelles of histidine functionalized surfactants. Rate comparisons... 

Luk Y-Y, Abbott NL. Applications of functional surfactants. Curr Opin Colloid Interface Sci 2002 7 267-275. 

Yet another use of surfactants with limited stability is to have the cleavage product impart a new function. For instance, a surfactant used in personal care formulations may decompose on apphcation to form products beneficial to the skin. Surfactants that impart a new function after cleavage are sometimes referred to as functional surfactants. 

Surfactants having a positive curvature, above a given concentration usually called the critical micellar concentration, cmc, self-assemble to form oil-in-water aggregates called normal micelles. The surfactant most often used is sodium dodecyl sulfate, Na(DS) or SDS. To make particles, the counterion of the surfactant is replaced by ions which participate in the chemical reaction. These are called functionalized surfactants. 

Synthesis of CdS has been performed by using cyclohexane, isooctane or decane as the bulk solvent. The data are compared to those obtained with isooctane. Figure 3.4. shows the absorption onset and the CdS diameter obtained at various water contents, using Cd(N03) reactant (Fig. 3.4.4A and B) or functionalized surfactant Cd(AOT)2 (Fig. 3.4.4C and D). At low water content, w < 10, similar sizes are obtained, whatever bulk solvent is used. These indicate that for low water content, size control is not governed by exchange micellar rate but only by preparation mode and by the nature of ions in excess (Cd2+ or S2 ). 

Rh-coated CdS resulted in sacrificial water photoreduction a thiol-functionalized surfactant acted as the sacrificial electron donor, system could be recycled... 

Figure 9. An idealized model for the cyclic oxidation-reduction process using thiol-functionalized surfactant, incorporated into DODAC vesicles together with Rh-coated colloidal CdS, for sustained hydrogen generation under visible light irradiation in one part of the cycle.

There are a number of books [168-173] and reviews [68,174,175] that provide good starting points. Refs. [168,176-178] discuss methods for the determination of anionic surfactants, which are probably the most commonly encountered in industry. Most of these latter methods are applicable only to the determination of sulfate-and sulfonate-functional surfactants. Probably the most common analysis method for anionic surfactants is Epton s two-phase titration method [179,180] or one of its variations [171,172,181-183]. Additional references are provided elsewhere [163], Aqueous surfactant micellar systems have also been utilized successfully in virtually every area of analytical chemistry (for example, [184—186]). 

Lauryl hydroxysultaine is completely hydrolytically stable, a fairly high foamer and tolerant of electrolyte. It is used as a detergent in both strongly acid and strongly alkaline cleaners where amido-functional surfactants would not have sufficient shelf life due to hydrolysis. 

Consequently, new investigations dealing with reactions in micellar solutions composed of functional surfactants, or mixtures of inert and functional surfactants, continue to appear in the literature. An interesting study of acid-catalyzed hydrolysis of 2-(p-tetradecyloxyphenyl)-l,3-dioxolane (p-TPD) in aqueous sodium dodecyl sulfate (SDS) solutions has been reported [13]. In this case,/ -TPD behaves as a non-ionic functional surfactant and apparently forms non-ideal mixed micelles with the anionic surfactant (SDS). Based on the observed kinetic data, the authors propose that, at elevated temperatures, the thermodynamic non-ideality results in the manifestation of two populations of micelles, one rich in SDS and the other rich in/>-TPD. 

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). 

Significant improvements in the properties can also be achieved by using the various types of functionalized surfactant aggregates. Scientific endeavors for the design of enzyme mimics will continue until natural enzymes are engineered such that they can participate in the processes such as decontamination of toxic substances. 

Also, use of functionalized surfactants as the reversed micellar formers (8) tailored for specific components of mixtures should be synthesized and evaluated. Further development of specific affinity ligand co-surfactants for such tailored extractions should also lead to selective separation and purification of biomaterials (377). 

The use of other novel surfactant systems, such as chiral, fluoro, or functional surfactants should aid in development of more selective procedures in many areas of separation science due to the specific chiral, fluorine, or binding interactions possible. We have recently managed partial optical resolution using chiral mixed micel-... 

Other functionalized surfactants having different complexing groups and modular lipophilic chains, together with various nonionic solubilizing surfactants, are presently under investigation in our laboratories. 

Another technique was proposed as an efficient method for the preparation of surface-template resins. In surface imprinting, a functional surfactant (emulsilier) that is capable of binding metal ions and functions as a vinyl monomer must orient at the interface between the matrix monomers and water and emulsify the mixture. 

Kakoi T, Goto M, and Nakashio F. Development of bi-functional surfactant for extraction of platinum with hquid surfactant membranes. J Chem Eng Jpn 1995 28 854-856. 

Uddin MS and Kathiresan M. Extraction of metal ions by emulsion liquid membrane using bi-functional surfactant equilibrium and kinetic studies. Sep Purif Technol 2000 19 3-9. 

Both micellar and microemulsion media have been investigated as candidates for solubilization and detoxification of nerve agents. Normal micelles, however, do not appear to bind Sarin well (J ) and oximate functionalized surfactants are severely limited by their low water solubility (2 ). These oximate functionalized surfactants have been shown to be excellent... 

Hydroxy-functionalized surfactant the hydroxy group in the surfactant... 

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