Amphoteric surfactants common types

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). 

Numerous laboratory sorption studies have been conducted for the most common surfactants non-ionics, such as AE and alkylphenol ethox-ylates (APEOs) anionics such as LAS, secondary alkane sulfonates (SASs) and sodium dodecylsulfates (SDS) and on different natural sorbents [3,8,15-17], Until now, cationic and amphoteric surfactants have received less study than the other types, probably because they represent only 5 and 2%, respectively, of the total surfactant consumption in Western Europe (1998) [18]. 

The shape, size, and structure of these dispersed droplets depend upon a multitude of variables including the surfactant type, ionic strength, the presence of cosurfactant(s), and the amount of Avater. Commonly used surfactants are of the five general categories anionic, cationic, nonionic, amphoteric and zwitterionic. The nature of amphoteric surfactants, i.e., whether or not they behave as anionic or cationic species, is dependent on the pH or ionic strength of the aqueous phase. 

The variety and range of amphoteric surfactant types are quite large. The following are the characteristic properties that amphoteric surfactants have in common [3] ... 

These types of surfactants exhibit anionic properties at high pH and cationic properties at low pH and may be categorized as [87] jS-iV-alkylaminopropionic acids, TZ-alkyl-yS-iminodipropionic acids, imidazoline carboxylates, W-alkylbetaines and amine oxides. The sulfobetaines are amphoteric at all values of pH. These surfactants are not commonly used in emulsion polymerization formulations. 

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