Glutamate surfactants

Although glutamate surfactants are effective and mild cleansing agents, there are only a few commercially available products. The major reason is price, for they are relatively expensive (generally 5-10 times the price of SLES). Clariant has developed a new process for increasing the production of acyl glutamates. The process is expected to reduce the price from the current 4.50-5/lb to about 2.50/lb [13]. 

For the separation of amino acids, the applicability of this principle has been explored. For the separation of racemic phenylalanine, an amphiphilic amino acid derivative, 1-5-cholesteryl glutamate (14) has been used as a chiral co-surfactant in micelles of the nonionic surfactant Serdox NNP 10. Copper(II) ions are added for the formation of ternary complexes between phenylalanine and the amino acid cosurfactant. The basis for the separation is the difference in stability between the ternary complexes formed with d- or 1-phenylalanine, respectively. The basic principle of this process is shown in Fig. 5-17 [72]. 

In the personal care market, fatty acid derivatives of proteins and amino acids (glutamic acid) are mainly used in mild shower and bath products, mild shampoos, surfactant-based face cleansers, cold-wave preparations and fixatives, baby wash formulations, as well as special emulsifiers for leave-on products. 

The mechanism of interaction of amino acids at solid/ aqueous solution interfaces has been investigated through adsorption and electrokinetic measurements. Isotherms for the adsorption of glutamic acid, proline and lysine from aqueous solutions at the surface of rutile are quite different from those on hydroxyapatite. To delineate the role of the electrical double layer in adsorption behavior, electrophoretic mobilities were measured as a function of pH and amino acid concentrations. Mechanisms for interaction of these surfactants with rutile and hydroxyapatite are proposed, taking into consideration the structure of the amino acid ions, solution chemistry and the electrical aspects of adsorption. 

The adsorption of amino acids on rutile and hydroxyapatite exhibits some characteristics of specific adsorption. The results can be interpreted in terms of electrostatic models of adsorption, however, if reorientation of adsorbed molecules is taken into consideration. The electrokinetic behavior of hydroxyapatite in glutamic acid is complicated because of a chemical reaction, possibly involving calcium ions. The study shows that it is necessary to take into consideration the orientation of adsorbed molecules, particularly for zwitterionic surfactants. 

Surfactants have been used to solubilise lipases in organic solvents (Okahata and Mori, 1997). One method starts with mixing aqueous solutions of the surfactant and the enzyme. The enzyme-surfactant complex precipitates and can subsequently be dissolved in organic media. Several surfactants have been tested and especially good results have been obtained with dialkyl glucosyl glutamates. In one case it was shown that the complex consisted of one enzyme molecule surrounded by approximately 150 surfactant molecules. 

Neutral. A bis(ethylenediamine) structure has been incorporated into the surfactant molecule -Ci6H33C(H)[CON(H)(CH2)2NH2]2 in older to incorporate metal ions in an LB film structure via coordination instead of ionic complexation as occurs for anionic/cationic amphiphiles (14). Also, films of n-octadecylacetoacetate containing Cu2+ have been prepared, and exposure to H2S has resulted in the formation of a copper sulfide (39). Ditetradecyl-A-[4- [6-(A, N, W -trimethyl-ethylenediamino)-hexyl]oxy]benzoyl]-L-glutamate (DTG), which also contains the ethylenediamine unit, was used to make self-assembled films containing Cd2+ (40). 

Controlled evaporation of SUVs and MLVs on substrates has been shown to result in the formation of ultrathin films which retained the regular bilayer structure of vesicles [69, 425-427]. These immobilized bilayers, termed as cast multibilayers , cast multibilayers , or ordered cast (ultrathin) films , have provided an alternative to LB films [425-446]. Alkylammonium surfactants with azobenzene (33) and glutamate (34) functionalities have been used, for example, in the preparation of cast-film-forming SUVs. X-ray diffraction... 

N. Garti, H. Zour, The effect of surfactants on the crystallization and polymorphic transformation of glutamic acid, J. Cryst. Growth 172 (1997) 486-498. 

There has been considerable interest from both academics and industry in this reaction since 1980. There are a wide number of uses for the amido acid products surface-active agents and specialty surfactants (Cio-Cie amido acids), intermediates for aspartame sweeteners (phenylalanine), food additives (monosodium glutamate), and chelating agents (iminoacetic acid and polyamido acids). Knifton (Texaco) has done extensive studies of this reaction, as have Ojima and coworkers. ... 

Due to the difference of the polymer adsorption onto different faces of different crystal forms, polymer adsorption onto the crystal face has played an important role in crystal polymorphic transformationJ Garti and Zour have studied the effects of surfactants on the polymorphic transformation of glutamic acid. Glutamic acid has two crystal forms, a and p, with the p-form being more stable than the ot-form. Those surfactants that preferentially adsorb onto the surface of the ot-growing crystals retard the transformation of the ot-form to the p-form. A Langmuir analysis indicates that the kinetic coefficient of crystal polymorphic transformation is related to the volume of the surfactant adsorbed at the crystal surface. 

Furthermore, a polycarboxybetaine with a peptide main chain was synthesized from poly(methyl L-glutamate) [57]. Several zwitterionic monomers based on isobutylene with long alkyl spacers between the polymerizable group and the zwitterionic moiety exhibit surfactant properties. They do not undergo free radical homopolymerization, but are copolymerizable with other monomers [58]. 

An alternative surfactant combination which is free of ethoxylated molecules is based on rapeseed sorbitol ester and sodium lauroyl glutamate [53]. Here, the phase inversion from a w/o- to an o/w-emulsion can be initiated by the addition of lauroyl glutamate, which is a hydrophilic surfactant, instead of using the temperature. Penetration studies for the release of Vitamin E from PIT emulsions in comparison with other formulation concepts have been performed [54]. It has been shown that the penetration of Vitamin E into the skin is better for a w/o-cream than a PIT emulsion. The free diffusion of Vitamin E might be hindered by the oil-water interface, which acts as a barrier around the oil droplets. 

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