Surfactant aggregates applications

Although the proposed theory has been used effectively in several practical applications, no experimental proof has been given that the oil solubilization rate is a function of surfactant aggregate size. In view of the importance of solubilization and the existence of practical methods of measuring and controlling surfactant aggregate size, we decided to correlate the solubilization rate with micellar properties for some anionic and nonionic surfactants. 

It is no surprise then that surfactants are used so extensively in technical applications and of course this large surface area achieved by surfactant aggregates immediately inspires ideas of applications in basic chemistry too if for example the surfactant head had some catalytic properties, these could be extended and developed into an almost incredible dimension. 

One of the most important features of these analogues is their ability to be further cross-linked. The feasibility of the post-polymerization was demonstrated by the application of UV light induced polymerisation of the diynoic galactonamide 32b, which resulted in polymers retaining the superstructure of the surfactant aggregates.167 Similar observations were made for the dodecyl galactonamides 32a, which open up a route to the construction of pre-defined chiral nano-objects, which can be then stablized after assembly. 

Micelles and other organized surfactant aggregates are increasingly utilized in analytical applications (1.)- They interact with reagents and alter spectroscopic and electrochemical properties which, in turn, often results in increased sensitivities. Organized assemblies have also been employed in separation processes. Gas, liquid and thin layer micellar chromatographic techniques have been developed (2). 

The capacity of aqueous surfactant aggregates to incorporate solutes is the reason for the widespread use of such systems in industrial, biological, pharmaceutical and synthetic chemical applications. Owing to the variety of applications, the investigation of the solubilization properties of surfactants has attracted the interest of many researchers for a long time. Knowledge on the nature of solubilization and the chemical and physical properties of the solute is of fundamental importance. 

Surfactant aggregates (microemulsions, micelles, monolayers, vesicles, and liquid crystals) are recently the subject of extensive basic and applied research, because of their inherently interesting chemistry, as well as their diverse technical applications in such fields as petroleum, agriculture, pharmaceuticals, and detergents. Some of the important systems which these aggregates may model are enzyme catalysis, membrane transport, and drug delivery. More practical uses for them are enhanced tertiary oil recovery, emulsion polymerization, and solubilization and detoxification of pesticides and other toxic organic chemicals. 

Harwigsson, I. Surfactant Aggregation and Its Application to Drag Reduction. Ph.D. dissertation, Lund University, Sweden. 1995. 

The role of the surfactants is two-fold first, to provide a locus for the monomer to polymerise, and second, to stabilise the polymer particles as they are formed. In addition, surfactants aggregate to form micelles (above the cmc), and these can solubilise the monomers. In most cases a mixture of anionic and nonionic surfactant is used for the optimum preparation of polymer latexes. Cationic surfactants are seldom used, except for specific applications where a positive charge is required on the surface of the polymer particles. 

We now turn to the more complex situation where both polyelectrolytes and surfactant are present in solution and adsorption is allowed to occur from this mixture. Polyelectrolyte and surfactant mixtures are used in numerous applications such as pharmaceuticals, laundry, and cosmetics, just to mention a few [4], Sometimes polyelectrolytes and surfactants are unintentionally mixed and due to mutual interaction provide unexpected properties to the mixture. Sometimes they are purposefully added together to fill the function of changing the properties and feel of surfaces, e.g., hair or fabrics, or to act as deposition aids. It is thus important to understand how these mixtures act when they are first mixed in bulk and subsequently transferred to a surface, and how the properties of polyelectrolyte-surfactant aggregates formed in bulk correlate with the properties of such aggregates adsorbed at a solid-liquid interface. Further, it is necessary to learn what happens with the polyelectrolyte-surfactant mixture at the surface when it is diluted with water. 

Although the method outlined above is certainly useful, one should be aware of the limitations inherent in the approach. First, a direct application of Eq. (2) assumes infinite dilution. As surfactant aggregates are self-assembled units, one must be aware of the fact that dilution may change their properties. At higher concentrations, interactions become important [cf Eq. (3)], and these must be taken into account [31,32]. In fact, the obstruction effects can be used to advantage, as information pertaining to the interparticle interactions can be derived from them. 

Shen, Y. F, Zhang, Y. ]., Kuehner, D., Yang, G. F, Yuan, F. Y., and Niu, L. (2008]. ion-responsive behavior of ionic-liquid surfactant aggregates with applications in controlled release and emulsification. Chem. Phys. Chem., 9, pp. 2198-2202. 

Because the activity of surfactants used below cannot reach their theoretical maximum as determined by the thermodynamics of surfactant aggregation (see also Chapter 15), they will also be unable to achieve their maximum degree of adsorption at the solution-vapor interface. It is therefore important to know the value of Tk for a given system before considering its application. Most surfactants, however, are employed well above their Krafft temperature, so that the controlling factor for the determination of their effectiveness will be the cmc. 

As noncovalent interactions are very important in controlling surfactant aggregation, and given the wide range of real-world applications of colloids, supramolecular chemists have recently increasingly extended their... 

An interesting application of aqueous IL microemulsions is to develop IL polymer materials incorporating enzymes that can be used as active, stable, and reusable biocatalysts [65].The IL l-vinyl-3-ethylimidazolium bis(trifluoromethylsulfonyl) amide ([veim][Tf2N] see Scheme 13.2) was used as the continuous phase. Incorporation of proteins in IL-based polymer frameworks is generally difficult because they are insoluble in most ILs.To overcome this limitation, the authors first employed water/Tween-20/[veim][TfjN] microemulsions to solubilize the enzyme in an IL phase and then incorporated the enzyme within these surfactant aggregates into IL polymer frameworks via polymerization in the presence of an IL-soluble cross linker and initiator. 

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