Shampoo

These are normally a gelled surfactant solution of well-defined associated structures, e.g. rod-shaped micelles (see Chapter 2). A thickener such as a polysaccharide may be added to increase the relaxation time of the system. Interaction between the surfactants and polymers is of great importance. 

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Chloroacetic acid can be esterified and aminated to provide useful chemical intermediates. Amphoteric agents suitable as shampoos have been synthesized by reaction of sodium chloroacetate with fatty amines (4,5). Reactions with amines (6) such as ammonia, methylamine, and trimethylamine yield glycine [66-40-6J, sarcosine [107-97-17, and carhoxymethyltrimethylammonium chloride, respectively. Reaction with aniline forms /V-phenylglycine [103-01 -5] a starting point for the synthesis of indigo (7). 

Cosmetics and Pharmaceuticals. The main use of hexadecanol (cetyl alcohol) is in cosmetics (qv) and pharmaceuticals (qv), where it and octadecanol (stearyl alcohol) are used extensively as emoUient additives and as bases for creams, Hpsticks, ointments, and suppositories. Octadecenol (oleyl alcohol) is also widely used (47), as are the nonlinear alcohols. The compatibiHty of heavy cut alcohols and other cosmetic materials or active dmg agents, their mildness, skin feel, and low toxicity have made them the preferred materials for these appHcations. Higher alcohols and their derivatives are used in conditioning shampoos, in other personal care products, and in ingested materials such as vitamins (qv) and sustained release tablets (see Controlled RELEASE technology). 

Shampoos have been prepared in various forms, and have included systems that are thick and thin, clear and opaque, pourable Hquids, soflds, gels, pastes, powders, flakes, and aerosol types. In many cases, shampoos have been prepared and directed for various hair types, eg, normal, dry, damaged, and color treated. Most marketed shampoos (ca 1993) are primarily clear Hquid and opaque lotion types gel and paste forms also are available. Aerosol shampoos are available to the consumer however, their impact on the market has been limited to the dry shampoo aerosol. 

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