Cosmetics, amphoteric surfactants

Cocamidopropyl betaine (Table 1.4) is the most prominent representative of the class of amphoteric surfactants. Due to the synergism with other surfactants and its gentleness to the skin and mucous membranes, cocamidopropyl betaine performs well in shampoo and cosmetics where its dosage lies in the order of 1-5% [27]. 

Cocamidopropyl betaine is the most commonly used amphoteric surfactant in shampoos, bath products, and other cosmetic products. It is popular because of its relatively low irritation potential. 

The change in charge with pH of amphoteric surfactants affects their properties, such as wetting, detergency, and foaming. Atthe i.e.p., the properties of amphoterics resemble those of nonionics very closely, but below and above the i.e.p. the properties shift towards those of cationic and anionic surfactants, respectively. Zwitterionic surfactants have excellent dermatological properties, and also exhibit low eye irritation consequently, they are frequently used in shampoos and other personal care products (e.g., cosmetics). 

Ampholyt [H lsAG] Glycinates betaines amphoteric surfactant for cosmetics, shampoos, detergents. 

Schercoteric. [Scher] Imidazolmium amphoterics surfactants for cosmetic and industrial cleaners. 

Lexaine. [Inolex] Betaines, sultaines amphoteric surfactants, vise, builders, foam boosters, diickeners for detergent systems, cosmetics. 

This class of surfactant includes those that cany both positive and negative diarges. Depending on the pH of the preparation, this group behaves as a cationic, anionic, or nonionic species. In the cosmetics held, these surfactants are frequently applied in skin or hair formulations as relatively mild detergents. They are also used for their capacity for reducing the irritation of anionic surfactants. These surfactants are commonly accepted to be noninitant to the eyes and have consequently been used in baby shampoos. Amphoteric surfactants are very much used in cosmetics, but they are not found in the different pharmacopoeia studied here. 

Uses Leveling agent for hair dyes coemulsifier and stabilizer for cosmetic emulsions neutralizer plasticizer antistat in acidic systems emulsifier for latex, dyes, and oils lubricant, softener, scouring agent, dye leveling agent and antistat for textiles in syn. latex paints dispersant acid cleaners process modifier in polymer industry raw material for quat. and amphoteric surfactants... 

Broad pH surfactant compatibility characteristics have contributed to greater usage of amphoteric surfactants in a variety of leave-on cosmetic and skin treatment... 

As the line between therapeutic cosmetics (cosmeceuti-cals) and drugs becomes more vague, the use of amphoteric surfactants in the development of products which are evaluated through clinical trials is likely to increase. This is especially true concerning the use of amphoteric surfactants in the oral care industry. 

Chun, H., Amphoteric surfactants as stabilizers for cosmetic type emulsions, in Proceedings of the 1978 Annual Scientific Seminar of the Society of Cosmetic Chemists, 1, December 1978. 

As shown in Figure 22.1, 7% of total surfactants are used in cosmetics and pharmaceuticals, especially in personal care products such as shampoos, bath preparations or toothpastes. Surfactants are important in their function as emulsifiers in creams and lotions. A great variety of anionic, nonionic, cationic and also amphoteric surfactants are used here. 

Amphoteric surfactants have a special application profile which favours their use mainly in cosmetics. In recent years, they have also found increasing application in the development of dishwashing agents or household cleaners. Compared to the amounts produced world-wide of anionic and nonionic surfactants, the volume of amphoterics is still relatively small. For cosmetic products, their consumption in Europe in 1992 was about 15 000 t. The main carbon chain includes the Cg-Cig range. The zwitterionic character of amphoterics strongly influences their particular behaviour, i.e. both anionic and cationic... 

The formulation class (tooth paste, shampoo, fabric softener, etc.) provides basic information about the components present. Standard shampoo formulations contain two types of surfactants (either two anionic or one anionic and one amphoteric surfactant) foam booster (nonionic surfactant) conditioner, viscosity improver, opacifier, dye, perfume, chelate, and preservatives. Normally, formulated products are available as liquid, solid, emulsion, dispersion, etc, with a great number of components (in some cosmetic products there may be 20 components) and some of them, such as the preservatives, are found at low concentrations. 

Studies performed by MS on cosmetic products demonstrate the utility of this technique for analysis of hair-care surfactants. After sample pretreatment for the separation of different kinds of surfactant, the usual identification of anionic surfactant such as AE, AES, and less common surfactants (lauryl sulfosuccinate, N-acyl-N-methyl taurate, paraffin sulfonate) is possible. Amphoteric surfactants (cocoamido-propylbetaine) and those present less frequently (lauryl hydroxysultaine) have been identified by this technique as well. For other kinds of components... 

Broad pH surfactant compatibility characteristics have contributed to greater usage of amphoteric surfactants in a variety of leave-on cosmetic and skin treatment products. These include alpha hydroxy acid treatment creams, skin desquamation aids, cleansing gels, and massage creams. Excellent skin... 

Domingo, X., B. M. Phillips, J. Sanchez Leal, T. Garcia, A. Garbayo. Sodium lauryl sulfate/amphoteric surfactants interactions Selective diffusion through a collagen film. Int. J. Cosmet. Sci. 13 263, 1991. 

The amphoteric surfactants are relatively expensive products compared to anionic surfactants. Thus, it is not surprising that they are primarily being utilized at low concentrations in cosmetic formulations. A review of 438 shampoos of the U.S. market reveals that appreciable quantities, for example, >5% of alkylamido betaines and imidazolinium surfactants were found in only 8.7% and 13.5%, respectively, of the investigated shampoos. Alkyl betaines were found in a limited number of cases, whereas sulfo betaines were not found in this stndy [4,5]. Since these studies were made, the market has focused on mild products. The change in the U.S. market from bar to liquid soaps has increased the use of alkylamidopropyl betaines. 

Ellis, P. R., P. J. Derian, R. Vokov. Amphoteric surfactants—the next generation. Euro Cosmet. 2 14-16, 1994. 

Dimethylaminopropylamine is an aliphatic amine present in amphoteric surfactants such as liquid soaps and shampoos. It is present as an impurity responsible for allergy from cocamidopropylbetaine. It is structurally similar to diethylaminopropylamine. It is also used as a curing agent for epoxy resins and as an organic intermediate in chemical syntheses (ion exchangers, additives for flocculants, cosmetics and fuel additives, dyes and pesticides). 

Amphoteric polysaccharides are those polyglycans capable of carrying both cationic and anionic charges on the same chain. The term amphoteric derives from the Greek am-photeros, which means both. There are very few naturally occurring amphoteric polysaccharides most of those used cosmetically are seminatural derivatives. Amphoteric polysaccharides are relatively unknown and underutilized in cosmetics although the use of amphoteric surfactants in personal care is quite common. 

Aminocarboxylic ampholytes have been used extensively in hair care and other cosmetic formulations. These materials are substantive to hair and have also been claimed to possess antistatic and bacteriostatic properties [45]. Many amphoteric surfactants have poor foaming properties and are blended with foaming anionics. The triethanolamine salt of Deriphat 170C shows exceptional foam volume. Optimum foaming properties of the A-alkyl-P-aminopro-... 

In the United States and Europe, the mildness concept is led by isethionate for a cleansing bar by Lever Brothers (Unilever Affiliate), followed by an amphoteric surfactant and nonionic alkylglycocide, which are really secondary surfactants to reduce the potential for irritation with a combination of typical anionics. The utilization of acylamino acid surfactants has just started in Western markets. In Europe, Biersdorf was the first company to use acylglutamate in a product for the mass market, although several upscale cosmetic cleansers pioneered its use on a small scale. 

A characteristic example in the field of cosmetics is the separation and determination of surfactants in shampoos, which contain various combinations of anionic, cationic, nonionic, and amphoteric surfactants. The surfactant combination is designed to influence the essential characteristics of the shampoo cleansing, foam, conditioning, and viscosity. Laurylether sulfates and alkylben-zene sulfonates are common anionic surfeictants used in shampoos to provide lather and cleansing. The only required sample preparation step is the dilution of the product to be analyzed in deionized water and subsequent membrane filtration (0.45 pm) prior to injection. Figure 10.200 illustrates the gradient... 

Amphoteric surfactants by definition are chimeric, exhibiting anionic character in alkaline solution, nonionic character near their isoelectric point, and cationic character in acidic solution [73]. As a result of their complex charge characteristics, their interactions with interfaces must be examined iudividually and as a function of pH. For example, the adsorption of alkyl betaines firom solution onto wool keratin is much greater at acidic than alkalide pH values. Although amphoteric surfactants are used extensively to improve the cosmetic attributes of many consmner products [74], their interactions with skin have received little attention. 

However, not all surfactants inactivate enzymes [101]. For example, the nondenaturing nonionic surfactants have little effect on most enzymes [75]. Moreover, Ernst [102] has shown that amphoteric surfactants protect enzymes from inactivation by anionic and cationic surfactants, possibly by forming mixed micelles with them. Indeed, cosmetic chemists frequently use amphoteric surfactants to reduce the irritation potential of anionic surfactants [59]. 

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