Alkylated surfactants

Fatty Held—Peptide Condensates. These proteia detergents are reaction products of fatty acid chlorides and hydrolyzed proteias. They are used ia shampoos because of their mildness on skin, hair, and to eyes when used alone or ia combination with alkyl surfactants (8). 

At the end of the 1990s statistics show that the non-ionic surfactants achieved the highest growth in production rates world-wide, though anionic surfactants (anionics) maintained the dominant position in the surfactant market. Today they are produced in a larger variety by the petrochemical industry than all other types of surfactants. Their production spectrum covers alkyl sulfates (ASs), secondary alkane sulfonates (SASs) and aryl sulfonates and carboxylates via derivatives of partly fluorinated or perfluorinated alkyl surfactants to compounds with an alkylpolyglycolether substructure combined with an anionic moiety such as alkylether sulfates (AESs), phosphates, phosphonates or carboxylates. 

P. Poulin and J. Bibette Influence of the Alkyl Surfactant Tail on the Adhesion Between Emulsion Drops. Langmuir 15, 4731 (1999). 

For alkyl surfactants with tic carbons in their tails, Eqs. (12-1) and (12-15) yield... 

Schwuger [4] has investigated the effects of ether groups on the solubility, surface properties, and detergency of alkyl ether sulfates. Addition of ethylene oxide groups to the alkyl surfactants increases solubility, thus reducing the formation of precipitates and maintaining foam volume in the presence of Ca2+ and Mg2+ ions. The use of ether sulfates would be preferred over that of alkyl sulfates for a clear formulation. 

Drug delivery from LLC phases of oligo(ethylene oxide)-alkyl ether (i.e., (E0) -0-alkyl) surfactants have also been explored but to a much lesser extent than GMO. For example, the L, Qn, and Hu phases of commercial Brij-96 surfactant (i.e., (EO)io-O-oleyl) (Fig. 18) formed with water and other additives, have been explored for release of ephedrine hydrochloride, tenoxi-cam [145], and topical dermal delivery of benzocaine [146]. Work in this area has found that the amount of water swelling the hydrophilic domains of the LLC phase increases drug diffusion and release [145]. In addition to this work, the L phase of the (EO)2i-0-stearyl/oil/water system has been explored for dermal delivery of itraconazole [147] and the L and Hi phases of the (E0)7-0-Ci3 i5 (i.e., Symperonic A7)/water system have been explored for the release of the model drug chlorhexidine diacetate [148]. 

In contrast to the LLC phases of GMO and (EO) -O-alkyl surfactants, only a handful of reports on the study of LLC phases of ionic surfactants for drug delivery are available. For example, the L, Qn, and Hu phases of the wa-ter/octanol/dioctyl sodium sulfosuccinate system have been studied for the transport of water and glucose across human skin [ 149]. Also, Qii phases of mixed ionic and uncharged phospholipids in water have been explored for the sustained in vitro release of timolol maleate, a drug for treatment of glaucoma [150]. 

This is attributed to the failure of the large molecules to enter the pores of the solid. More complex isotherm shapes are encountered as in the case of the adsorption of alkyl surfactants on silica and alumina. For example, the adsorption isotherm of sodium dode-cylsulfonate on alumina consists of four regions depending on the dominant adsorption mechanism. Adsorption of polymeric reagents on minerals typically results in a pseudo-Langmuirian type isotherm as shown in Fig. 4.7 for the adsorption of polyacrylamide on Na-kaolinite (Hollander et al., 1981). 

C. Burger-Guerrisi and C. Tondre, Conductometric study of the interaction of 1 1 electrolytes with nonionic surfactant having short polyoxyethylated chains Methanolic solutions of H- and F-alkylated surfactants and oil/water microemulsions, J. Colloid Interface Sci., 1987, 116, 100. 

S/MAh copolymers are post-esterifled with an alkyl surfactant in solvent. 

Whilst studies on linear alkyl surfactants are common, in recent years branched-chain nonionic surfactants have been studied as well as surfactants with novel head groups and surfactant mixtures. 

Arguably the most important parameter for any surfactant is the CMC value. This is because below this concentration the monomer level increases as more is dissolved, and hence the surfactant chemical potential (activity) also increases. Above the CMC, the monomer concentration and surfactant chemical potential are approximately constant, so surfactant absorption at interfaces and interfacial tensions show only small changes with composition under most conditions. For liquid crystal researchers, the CMC is the concentration at which the building blocks (micelles) of soluble surfactant mesophases appear. Moreover, with partially soluble surfactants it is the lowest concentration at which a liquid crystal dispersion in water appears. Fortunately there are well-established simple rules which describe how CMC values vary with chain length for linear, monoalkyl surfactants. From these, and a library of measured CMC values (35-38), it is possible to estimate the approximate CMC for branched alkyl chain and di- (or multi-) alkyl surfactants. Thus, most materials are covered. This includes the gemini surfactants, a new fashionable group where two conventional surfactant molecules are linked by a hydrophobic spacer of variable length (38). 

Although bile salts have previously been found to inhibit the growth of holesterol crystols, Mufson and Higuch 34 have shown that they are not strongly idsorbed onto cholesterol particle surfaces. This behavior is in contrast to that of ilkyl surfactants, which are strongly adsorbed. The authors assume that the relatively igid bile salt molecules can be adsorbed only onto specific sites on the cholesterol lurfaces, while the more flexible alkyl surfactants are somewhat less restrained in heir interactions. 

While an increase in the hydrocarbon chain length in a series of normal alkyl surfactants between Cs and C20 carbon chains will have a minor effect on the effectiveness of a surfactant, other structural changes can produce... 

Trier, X., Granby, K., and Christensen, J. H. 2011. Tools to discover anionic and nonionic polyfluorinated alkyl surfactants by hquid chromatography elechospray ionisation mass spectrometry. J. Chromatogr. A 1218 7094-7104. 

Effects of ethoxylation of alkyl ether sulfates on solubility, surface properties, and detergency have been discussed in the literature. Ethoxylation of alkyl surfactants not only increases solubility, but also helps reduce the tendency for precipitation and decrease in foam volume in the presence of calcium and magnesium ions from hard water. 

Schultz MM, Barofsky DF, Field JA (2003) Fluorinated alkyl surfactants. Environ Eng Sci 20(5) 487-501... 

In addition to the studies of single chain alkyl surfactants previously described, we have also undertaken an inves-... 

The i and j snbscripts correspond to the various system components (layered silicate s, alkyl surfactant film a, and polymer p) and the LW and AB superscripts to the nature of interactions (apolar LW and polar AB). These relations can be... 

Following our prior nomenclature, dispersion would dictate a negative interaction energy change (upon mixing), which corresponds to a positive interfacial tension difference (yas Yps)- For an apolar (y 0) alkyl surfactant (e.g., dode-cane to nonadecane, y 26 mJ/m ) used to organically modify a typical silicate (e.g., montmorillonite, with y 66 mJ/m, y + 0.7 mJ/m, and yf 36 mJ/m ), miscibility would be achieved with any polymer for which... 

The increase in spontaneous curvature at a given concentration with increasing length of the hydrophihc chain is clear as the number of units increases from 3 to 50 [13,16,19]. The cubic phases for 20 35 oxyethylene units are located between the miceUar and the hexagonal phases, which implies micellar cubic phases. It can be noted that the temperature stability of the liquid crystalline phases for sterol surfactants with 20 and 30 polyoxyethylene units is remarkably high compared with those formed by polyoxyethylene alkyl surfactants (see Fig. 4c, d) [16]. 

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