Single-tail Surfactant

Anionic surfactants are the most commonly used type in the emulsion polymerization. These include sulfates (sodium lauryl sulfate), sulfonates (sodium dodecylbenzene sulfonate), fatty acid soaps (sodium or potassium stearate, laurate, palmitate), and the Aerosol series (sodium dialkyl sulphosuccinates) such as Aerosol OT (AOT, sodium bis(2-ethylhexyl) sulfosuccinate) and Aerosol MA (AMA, sodium dihexyl sulphosuccinates). The sulfates and sulfonates are useful for polymerization in acidic medium where fatty acid soaps are unstable or where the final product must be stable toward either acid or heavy-metal ions. The AOT is usually dissolved in organic solvents to form the thermodynamically stable reverse micelles. [22] Nonionic surfactants usually include the Brij type, Span-Tween 80 (a commercial mixture of sorbitol monooleate and polysorbate 80), TritonX-100[polyoxyethylene(9)4-(l,l,3,3-tetramethylbutyl)-phenyl 

Cationic surfactants such as dodecylammonium chloride (DAC), cetyltrimethylammonium bromide (CTAB), and dodecyltrimethylam-monium bromide (DTAB) are much less frequently used than anionic surfactants due to their relatively inefficient emulsifying action or adverse effects on initiator decomposition. In addition, the cationic surfactants are much more expensive than anionic surfactants. 

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Kaler, E. W., Murthy, A. K., Rodriguez, B. E., and Zasadzinski, J. A. N. (1989). Spontaneous vesicle formation in aqueous mixtures of single-tailed surfactants. Science, 245, 1371. ... 

Generally, vesicles are prepared from double-tailed surfactants, and a simple single-tailed surfactant cannot form vesicles due to its relatively large hy-... 

For single-tailed surfactants, the parameter u/ao t is often less than unity, and type I... 

Finally we note that, apart from double-tailed surfactant molecules, vesicular aggregates can also be formed from a number of other building blocks, including nonionic amphiphiles to form niosomes, single-tailed surfactants and complex (co)polymers, polypeptides, and dendrimers. In this chapter we restrict our discussion to encapsulation processes by vesicles formed from synthetic surfactants and phospholipids. 

Irradiation of 2-oxooctanoic acid 5 in water causes hydrogen abstraction and coupling of the persistent radicals. In this way, a single tailed surfactant is transformed into a double tailed surfactant 6, and this... 

Association colloids Homogeneous, thermodynamically stable solutions of spontaneous self-assembled surfactant aggregates micelles, typically composed of single-tailed surfactants reversed micelles in oil with water pools, vesicles typically composed of twin-tailed surfactants and microemulsions composed of at least oil, water, and surfactant and also with alcohols, either aqueous (oil-in-water droplets), bicontinuous (no droplets), or reverse (water-inoil droplets). 

Cytotoxic effects of the selected microemulsions (Table 1) were measured in MCF-7 cells. The performed cytotoxicity studies demonstrated that only bis(Ci2-LA) allows for near 75% viability of tumor cells. However, presented data reveal that the lactobionic derivative (systems 9,10) is slightly more safe for MCF-7 cells than the gluconic one (systems 7,8). In the presence of microemulsions stabilized with dicephalic (systems 3-6) and single-head single-tail surfactants (systems 1,2), a significant cytotoxic effect was observed. For these reasons, a utility of those systems for pharmaceutical uses should be limited. From the other hand potential applications of the (C12-DX X = GA and LA) systems will be studied for preparation of submicron particles type nanocapsules as useful carriers of the safe drug delivery. Moreover, only systems stabilized by the bis(Ci2-LA) appear to be relatively not toxic for MCF-7 breast cancer cells. Thus microemulsions stabilized by this surfactant may be used in... 

Compared to the conventional single-tail surfactants, the Gemini surfactants are related with the following merits [34-35]... 

The CMC values of Gemini surfactants are at least one order of magnitude lower than that of the corresponding conventional single-tail surfactants with a similar head group. The CMC values of commonly reported Gemini surfactants and some classic conventional surfactants are listed in Table 11.7. 

The hydrophobic tail of a surfactant is usually a hydrocarbon chain containing 8-16 methylenes. This may be either a straight or branched chain. Industrially a mixture of isomers is also common. Although single tailed surfactants are by far the most common, a number of double tailed compounds are also widely used [1]. 

Without addition of salt, Aerosol OT forms a much-studied region of oil-rich microemulsions (41). However, the even more hydrophilic single-tailed surfactants such as sodium dodecyl sulfate (SDS) and dodecyltrimethylammonium bromide (DTAB) are so far from the optimal hydrophilic-lipophilic balance that addition of salt alone is not enough for the formation... 

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