Zwitterionic surfactants

Mildness to human skin Use nonionic surfactants, zwitterionic surfactants, or a combination of both with additives that are antiirritants, such as modified proteins or polymers... 

In MECC anionic surfactants are most frequently used, but cationic surfactants are also very popular. In addition, chiral surfactants, nonionic surfactants, zwitterionic surfactants, biological surfactants, or mixtures of each are finding increasing use. In all categories, variations in alkyl chain length will affect resolution or selectivity, as will changes in buffer concentration, pH, and temperature or the use of additives such as metal ions or organic modifiers. Typical surfactant systems used in MECC are shown in Table 5.3. 

If pH extremes cannot be utilized, then either a coated capillary or buffer additives can be used. Without either of these, proteins might adsorb to the inner capillary wall. Adsorption will affect the separation and in some circumstances this may be beneficial. Additives that are often added to CE buffer systems include surfactants, zwitterionic salts, ethylene glycol, methyl-cellulose, organic modifiers, and quaternary amines. Capillary coatings include polyacrylamide, polyethyleneglycol, polyvinylpyrrolidone, and methyl-cellulose. Mazzeo and Krull65 discuss capillary coatings and buffer additives further. 

PEG-30 hydrogenated tallowamine PEG-200 trihydroxystearin Steareth-30 surfactant, wool wash compounds TEA-dodecylbenzenesulfonate surfactant, zinc galvanization Butoxynol-19 carboxylic acid surfactant, zwitterionic buffers N,N-Dimethyl-N-lauric acid-amidopropyl-N-(3-sulfopropyl)-ammonium betaine N,N-Dimethyl-N-myristyl-N-(3-sulfopropyl)-... 

Surfactant-like zwitterionic hydroxamates show enhanced reactivities with 4-nitrophenyl acetate in cationic, zwitterionic, and non-ionic micelles compared with the non-micellar reaction. This is attributed to a hydrophobic ion pair and a lowering the pK of the hydroxamic acid. Similarly, sulphate transfer to surfactant zwitterionic hydroxamates occurs faster in the presence of cetyl-trimethylammonium bromide micelles than simple anionic hydroxamates." ... 

J. Zajac, Adsorption microcalorimetry used to study interfacial aggregation of quaternary ammonium surfactants (zwitterionic and cationic) on powdered silica supports in dilute aqueous solutions. Colloids Surf. A Physicochemical Eng. Aspects 167(1-2), 3-19 (2000). doi 10. 1016/S0927-7757(99)00479-3... 

Schemes for classifying surfactants are based upon physical properties or upon functionality. Charge is tire most prevalent physical property used in classifying surfactants. Surfactants are charged or uncharged, ionic or nonionic. Charged surfactants are furtlier classified as to whetlier tire amphipatliic portion is anionic, cationic or zwitterionic. Anotlier physical classification scheme is based upon overall size and molecular weight. Copolymeric nonionic surfactants may reach sizes corresponding to 10 000-20 000 Daltons. Physical state is anotlier important physical property, as surfactants may be obtained as crystalline solids, amoriDhous pastes or liquids under standard conditions. The number of tailgroups in a surfactant has recently become an important parameter. Many surfactants have eitlier one or two hydrocarbon tailgroups, and recent advances in surfactant science include even more complex assemblies [7, 8 and 9].

LDL compositions containing AOS, a sulfosuccinic acid ester, a zwitterionic and a nonionic surfactant have been described by Noguera et al. [76]. Such compositions have good cleaning and foaming power and are useful too for shampoo and laundry-cleaning purposes. 

The development of monoalkyl phosphate as a low skin irritating anionic surfactant is accented in a review with 30 references on monoalkyl phosphate salts, including surface-active properties, cutaneous effects, and applications to paste and liquid-type skin cleansers, and also phosphorylation reactions from the viewpoint of industrial production [26]. Amine salts of acrylate ester polymers, which are physiologically acceptable and useful as surfactants, are prepared by transesterification of alkyl acrylate polymers with 4-morpholinethanol or the alkanolamines and fatty alcohols or alkoxylated alkylphenols, and neutralizing with carboxylic or phosphoric acid. The polymer salt was used as an emulsifying agent for oils and waxes [70]. Preparation of pharmaceutical liposomes with surfactants derived from phosphoric acid is described in [279]. Lipid bilayer vesicles comprise an anionic or zwitterionic surfactant which when dispersed in H20 at a temperature above the phase transition temperature is in a micellar phase and a second lipid which is a single-chain fatty acid, fatty acid ester, or fatty alcohol which is in an emulsion phase, and cholesterol or a derivative. 

Surfactants used as lubricants are added to polymer resins to improve the flow characteristics of the plastic during processing they also stabilise the cells of polyurethane foams during the foaming process. Surfactants are either nonionic (e.g. fatty amides and alcohols), cationic, anionic (dominating class e.g. alkylbenzene sulfonates), zwitterionic, hetero-element or polymeric (e.g. EO-PO block copolymers). Fluorinated anionic surfactants or super surfactants enable a variety of surfaces normally regarded as difficult to wet. These include PE and PP any product required to wet the surface of these polymers will benefit from inclusion of fluorosurfactants. Surfactants are frequently multicomponent formulations, based on petro- or oleochemicals. 

The water-soluble calix[n]arenes 6.3 (n = 4, 6 and 8) containing trimethylammonium groups act as efficient inverse phase-transfer catalysts in the nucleophilic substitution reaction of alkyl and arylalkyl halides with nucleophiles in water (Eq. 6.19).40 In the presence of various surfactants (cationic, zwitterionic and anionic), the reactions of different halides and ketones show that the amount of ketone alkylation is much higher and that the reactions are faster in the presence than in the absence of surfactant aggregates.41 The hydrolysis of the halide is minimized in the presence of cationic or zwitterionic surfactants. 

Salkar RA, Jeevanandam P, Kataby G, Arana ST, Koltipin yuri, Palchik O, Gedanken A (2000) Elongated copper nanoparticles coated with a zwitterionic surfactant. J Phys Chem B 104 893-897... 

Harrison, C.R., Lucy, C.A. (2002). Determination of zwitterionic and cationic surfactants by high-performance liquid chromatography with chemiluminescent nitrogen detection. J. Chromatogr. A 956(1-2), 237-244. 

As mentioned in Table 8.1, amphoteric surfactants contain both an anionic and a cationic group. In acidic media they tend to behave as cationic agents and in alkaline media as anionic agents. Somewhere between these extremes lies what is known as the isoelectric point (not necessarily, or even commonly, at pH 7), at which the anionic and cationic properties are counterbalanced. At this point the molecule is said to be zwitterionic and its surfactant properties and solubility tend to be at their lowest. These products have acquired a degree of importance as auxiliaries in certain ways [20-25], particularly as levelling agents in the application of reactive dyes to wool. 

In the most recent method described by Hu et al. [239] for the direct determination of ultraviolet-absorbing inorganic anions in saline matrixes, an octadecylsilica column modified with a zwitterionic surfactant [3-(N,N-di-methylmyristylammoniojpropanesulfate] is used as the stationary phase, and an electrolytic solution is used as the eluent. Under these conditions, the matrix species (such as chloride and sulfate) are only retained weakly and show little or no interference. It is proposed that a binary electrical double layer is established by retention of the eluent cations on the negatively charged (sulfonate) functional groups of the zwitterionic surfactant, forming a cation-binary electrical double layer. 

Zwitterionic in the surfactant there are positively and negatively charged groups such as, for example, long-chain amino acids. 

One of the few zwitterionic surfactant used in CL reactions is /V-dodccyl-MA-dimethyl-ammonium-3-propane-l-sulfonate (SB-12). Particularly, SB-12 has been assayed in the study of the CL reaction of lucigenin with various biological reductants [10]. The results show that SB-12 enhances CL intensity of the luci-genin-glucose and lucigenin-fructose systems by factors of 3.0 and 1.5, respectively, compared to the intensity obtained in aqueous medium. In these conditions detection limits were found for-both analytes of 0.7 X 10 4 and 2.5 X 10 5 M, respectively. 

Most studies of micellar systems have been carried out on synthetic surfactants where the polar or ionic head group may be cationic, e.g. an ammonium or pyridinium ion, anionic, e.g. a carboxylate, sulfate or sulfonate ion, non-ionic, e.g. hydroxy-compound, or zwitterionic, e.g. an amine oxide or a carboxylate or sulfonate betaine. Surfactants are often given trivial or trade names, and abbreviations based on either trivial or systematic names are freely used (Fendler and Fendler, 1975). Many commercial surfactants are mixtures so that purity can be a major problem. In addition, some surfactants, e.g. monoalkyl sulfates, decompose slowly in aqueous solution. Some examples of surfactants are given in Table 1, together with values of the critical micelle concentration, cmc. This is the surfactant concentration at the onset of micellization (Mukerjee and Mysels, 1970) and can therefore be taken to be the maximum concentration of monomeric surfactant in a solution (Menger and Portnoy, 1967). Its value is related to the change of free energy on micellization (Fendler and Fendler, 1975 Lindman and Wennerstrom, 1980). 

The binding constants between the anionic substrates and cationic micelles are large because of the combination of coulombic and hydrophobic effects so rate enhancements may be large even with dilute surfactant. There is binding with non-ionic and zwitterionic micelles despite the absence of coulombic attraction (Bunton et al., 1975). 

D. Norton, J. Zheng, N. D. Danielson, and S. A. Shamsi. Capillary Electrochromatography-Mass Spectrometry of Zwitterionic Surfactants. Anal. Chem., 77(2005) 6874-6886. 

Amphiphile-oil-water system, temperature of, 16 424-426 Amphiphiles, 16 420 Amphiphile strength, 6 424 Amphiphilic chemicals, 17 56 Amphiphilic copolymers, 20 482 behavior of, 20 483 well-defined, 20 485-490 Amphiphilic molecules, 15 99-101 Amphiphilic plasticizers, 14 480 Amphiphilic polymer blend, 23 720 Amphiphilic polymers statistical, 20 484-490 stimuli-responsive, 20 482-483 Ampholytes, 9 746-747 Amphoteric cyclocopolymers, water-soluble, 23 721 Amphoteric starches, 4 722 Amphoteric (zwitterionic) surfactants, 24 148... 

Surfactants, 9 22-23, 784. See also Surface-active agents admixture for cement, 5 485 amphoteric, 14 709 amphoteric (zwitterionic), 24 148 anionic, 24 144-146 applications for, 24 119, 155-161... 

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