Surfactant amphoteric

Amphoteric surfactants may be cationic, anionic or non-ionic depending upon the pH of the aqueous solution (Table 4.3). A typical amphoteric surfactant can be 

Amphoteric surfactants offer an excellent degree of lubrication, corrosion inhibitor, and wetting action and provide a protective colloid for silk and wool processing. The major uses of amphoterics are in the scouring and dyeing of protein fibres to prevent chafing, crack marks and crow s feet. Amphoterics are comparatively expensive and some of them are not heat stable and hence cannot be used at elevated temperature. 

Amphoteric Surfactants Surfactants that have both positively and negatively charged hydrophilic groups within the molecule are referred to as amphoteric surfactants. The detergency of these surfactants varies with pH, and they show bacteriostatic activity at appropriate pH Amphoteric surfactants are effective leveling agents and aid in controlled diffusion of dyes and finishes onto the fiber. 

The nature of the impurities in the water has a major effect on soil removal from a textile. If the water is hard and contains significant amounts of calcium and magnesium salts as carbonates, sulfates, or chlorides, these salt ions will interfere with the soil lifting action of the surfactant unless appropriate water softening agents are added. Dissolved iron salts or the presence of clays, silts, and other colorants can interfere with cleaning, also. 

Amphoteric fluorinated surfactants are bifunctional compounds which can function both as anionic and as cationic surfactants, depending on the pH of the medium [87]. Amphoteric surfactants have at least one cationic group and at least 

In reality, surfactants having cationic and anionic functional groups are not always truly amphoteric. The dissociation constants of anionic and cationic functional groups are rarely equal. As a consequence, either the cationic or the anionic character may dominate the behavior of the surfactant in solution. 

Amphoteric fluorinated surfactants usually have a (1) carboxybetaine (I), (2) sulfobetaine (II), or (3) sulfatobetaine (III) structure  

Examples of amphoteric fluorinated surfactants are given in Table 1.6. 

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Major industrial uses for chloroacetic acid are in the manufacture of cellulose ethers (mainly carboxymethylceUulose, CMC), herbicides, and thioglycolic acid. Other industrial uses include manufacture of glycine, amphoteric surfactants, and cyanoacetic acid. 

Primary fatty amines also add (Michael addition) to esters of acryUc acid, H2C=CHCOOH, methacrylic acid, H2C=C(CH2)COOH, or crotonic acid, CH2CH=CHC00H. Hydrolysis of the Michael ester forms an amphoteric surfactant. Crotonic acid can be used to form the amphoteric compound... 

Anionic surfactants are the most commonly used class of surfactant. Anionic surfactants include sulfates such as sodium alkylsulfate and the homologous ethoxylated versions and sulfonates, eg, sodium alkylglycerol ether sulfonate and sodium cocoyl isethionate. Nonionic surfactants are commonly used at low levels ( 1 2%) to reduce soap scum formation of the product, especially in hard water. These nonionic surfactants are usually ethoxylated fatty materials, such as H0CH2CH20(CH2CH20) R. These are commonly based on triglycerides or fatty alcohols. Amphoteric surfactants, such as cocamidopropyl betaine and cocoamphoacetate, are more recent surfactants in the bar soap area and are typically used at low levels (<2%) as secondary surfactants. These materials can have a dramatic impact on both the lathering and mildness of products (26). 

Physical and ionic adsorption may be either monolayer or multilayer (12). Capillary stmctures in which the diameters of the capillaries are small, ie, one to two molecular diameters, exhibit a marked hysteresis effect on desorption. Sorbed surfactant solutes do not necessarily cover ah. of a sohd iaterface and their presence does not preclude adsorption of solvent molecules. The strength of surfactant sorption generally foUows the order cationic > anionic > nonionic. Surfaces to which this rule apphes include metals, glass, plastics, textiles (13), paper, and many minerals. The pH is an important modifying factor in the adsorption of all ionic surfactants but especially for amphoteric surfactants which are least soluble at their isoelectric point. The speed and degree of adsorption are increased by the presence of dissolved inorganic salts in surfactant solutions (14). 

Cationic, anionic, and amphoteric surfactants derive thek water solubiUty from thek ionic charge, whereas the nonionic hydrophile derives its water solubihty from highly polar terminal hydroxyl groups. Cationic surfactants perform well in polar substrates like styrenics and polyurethane. Examples of cationic surfactants ate quaternary ammonium chlorides, quaternary ammonium methosulfates, and quaternary ammonium nitrates (see QuARTERNARY AMMONIUM compounds). Anionic surfactants work well in PVC and styrenics. Examples of anionic surfactants ate fatty phosphate esters and alkyl sulfonates. 

Nonionic surfactants perform well in nonpolar polymers such as polyethylene and polypropylene. Examples of nonionic surfactants ate ethoxylated fatty amines, fatty diethanolamides, and mono- and diglycetides (see Amines, fatty amines Alkanolamines). Amphoteric surfactants find Httle use in plastics (134). 

QuaterniZation. Choline chloride [67-48-1] was prepared ia nearly quantitative yield by the reaction of trimethylamine [121-44-8] with ethylene chlorohydrin at 90—105°C and 981—1471 kPa (10—15 kg/cm ) pressure (44). Precursors to quaternary ammonium amphoteric surfactants have been made by reaction of ethylene chlorohydrin with tertiary amines containing a long chain fatty acid group (45). 

An unknown commercial detergent may contain some combination of anionic, nonionic, cationic, and possibly amphoteric surfactants, inorganic builders and fillers as weU as some minor additives. In general, the analytical scheme iacludes separation of nonsurfactant and inorganic components from the total mixture, classification of the surfactants, separation of iadividual surfactants, and quantitative determination (131). 

Many of the surfactants made from ethyleneamines contain the imidazoline stmcture or are prepared through an imidazoline intermediate. Various 2-alkyl-imidazolines and their salts prepared mainly from EDA or monoethoxylated EDA are reported to have good foaming properties (292—295). Ethyleneamine-based imida zolines are also important intermediates for surfactants used in shampoos by virtue of their mildness and good foaming characteristics. 2- Alkyl imidazolines made from DETA or monoethoxylated EDA and fatty acids or their methyl esters are the principal commercial intermediates (296—298). They are converted into shampoo surfactants commonly by reaction with one or two moles of sodium chloroacetate to yield amphoteric surfactants (299—301). The ease with which the imidazoline intermediates are hydrolyzed leads to arnidoamine-type stmctures when these derivatives are prepared under aqueous alkaline conditions. However, reaction of the imidazoline under anhydrous conditions with acryflc acid [79-10-7] to make salt-free, amphoteric products, leaves the imidazoline stmcture essentially intact. Certain polyamine derivatives also function as water-in-oil or od-in-water emulsifiers. These include the products of a reaction between DETA, TETA, or TEPA and fatty acids (302) or oxidized hydrocarbon wax (303). The amidoamine made from lauric acid [143-07-7] and DETA mono- and bis(2-ethylhexyl) phosphate is a very effective water-in-od emulsifier (304). 

Protease performance is strongly influenced by detergent pH and ionic strength. Surfactants influence both protease performance and stabiUty in the wash solution. In general, anionic surfactants are more aggressive than amphoteric surfactants, which again are more aggressive than nonionic surfactants. 

Amphoteric Surfactants, edited by B. R. Bluestein and Clifford L. Hilton (see Volume 59)... 

Amphoteric Surfactants Second Edition, edited by Eric G. Lomax... 

Amphoteric surfactants are those that are an acid and a base at the same time (like water is). Cocamidopropyl betaine, for example, is used in shampoos to stabilize foam and thicken the mixture. 

Whereas amphoteric surfactants are somewhat outside the scope of this book, amphoteric LSDAs are included here since they were investigated in the course of continuing research by the USDA team. Thus Parris and coworkers found that the sulfobetaine derivatives of fatty amides, in combination with soap, effectively dispersed soap curd [20]. They are synthesized as follows ... 

The sulfated alkylbenzenesulfonamides (no. 7-8) and alkylaroylsulfo-propionates (no. 9) were found to be efficient lime soap dispersants [27]. Although the nonionics (nos. 10-11) had low LSDR values they did not potentiate the detergency of soap and exhibited some antagonism. Amphoteric surfactants with alkyl side chains from C12 to C18 (nos. 12-13) possessed the lowest LSDR values, ranging from 2 to 4. The amine oxide derived from an aromatic sulfonamide had a low LSDR of 5 close to that of amphoterics. 

M. Dahanayake, J. Li, R. L. Reierson, and D. J. Tracy. Amphoteric surfactants having multiple hydrophobic and hydrophilic groups. Patent EP 697244, 1996. 

Kawase, J., Ueno, H., and Tsuji, K., Analysis of amphoteric surfactants by liquid chromatography with post-column detection. I. Mono- and dialanine surfactants, /. Chromatogr., 264, 415, 1983. 

Blends of surfactants optimized for seawater or reservoir brine salinity include linear alkylxylene sulfonate/alcohol ether sulfate mixtures (454,455). Alkyl- and alkylarylalkoxymethylene phosphonates (456), and amphoteric surfactants (457,458) have also been evaluated for use in surfactant flooding. 

Parris, N. (1978). Surfactant analysis by high performance liquid chromatography I. A rapid analysis for mixtures of amphoteric surfactants and soap. J. Am. Oil Chem. Soc. 55(9), 675-677. 

Parris, N., Linfield, W.M., Barford, R.A. (1977). Determination of sulfobetaine amphoteric surfactants by reverse phase high performance liquid chromatography. Anal. Chem. 49(14), 2228-2231. 

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. 

Ethoxylated products can also feature as amphoteric surfactants an example is compound 9.55, an alkylamine poly(oxyethylene) sulphate. Of particular interest in textile processing are the trisubstituted alkylamino acids known as betaines N-alkylbetaines (9.56 R = C8-C16 alkyl) and acylaminoalkylbetaines (9.57 R = C10-C16 alkyl) are typical [30]. 

EG Lomax, Amphoteric surfactants, 2nd Edn. (New York Marcel Dekker, 1996). 

A surfactant can be grouped in one of the four classes - anionic, nonionic, cationic and amphoteric surfactants, depending on what charge is present in the chain-carrying hydrophilic portion of the molecule after dissociation in aqueous solution. Tab. 4.1 shows examples of surfactants most commonly used for detergents. 

Anionic surfactants Nonionic surfactants Cationic surfactants Amphoteric surfactants... 

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