Amino acid surfactants with polymers

Studies on a mixture composed of amino acid-based surfactants have not been extensively made as compared to other surfactants, such as sodium do-decyl sulfate (SDS), and nonionics. To the best of our knowledge, there are few publications dealing with mixtures where amino acid-based surfactants, especially amino acid-based surfactants/polymers, are involved. With this in mind, this chapter first discusses methods for examining a mixture containing amino acid surfactants, essentially to provide prospective methods to smdy surfactant mixture systems. In addition, interactions of amino acid-based surfactants with other components, including inorganic and organic molecules, are reviewed. 

Oheme and co-workers investigated335 in an aqueous micellar system the asymmetric hydrogenation of a-amino acid precursors using optically active rhodium-phosphine complexes. Surfactants of different types significantly enhance both activity and enantioselectivity provided that the concentration of the surfactants is above the critical micelle concentration. The application of amphiphilized polymers and polymerized micelles as surfactants facilitates the phase separation after the reaction. Table 2 shows selected hydrogenation results with and without amphiphiles and with amphiphilized polymers for the reaction in Scheme 61.335... 

Isocyanide polymers functionalized with amino acid groups, typically di-or tripeptides containing histidine or serine, give enantioselective deacylation and rate enhancements. Their activity is increased by addition of cationic surfactants (Visser et al., 1985). 

Shea and colleagues [109-111] added an exciting contribution to this field They created molecular imprints for the peptide melittin, the main component of bee venom, in polymer nanoparticles, resulting in artificial antibody mimics that can be used for the in vivo capture and neutralization of melittin. Melittin is a peptide comprising 26 amino acids which is toxic because of its cytolytic activity. Shea and colleagues strategy was to synthesize cross-linked, acrylamide-based MIP nanoparticles by a process based on precipitation polymerization using a small amount of surfactant. To maximize the specificity and the affinity for melittin, a number of hydrophilic monomers were screened for complementarity with the template. The imprinted nanoparticles were able to bind selectively the peptide with an apparent dissociation constant of Ax>app > 1 nM [109]. 

Several recent patents describe the benefits of polymers in LDLDs (Table 7.15). Polymers are well known to interact with surfactants and provide many interesting properties. Some of the benefits claimed in the patents summarized in Table 7.15 are soil resistance due to amino acid copolymers, polyethylene glycol as a grease release agent, increased grease removal from polyoxyethylene diamine, enhanced foam volume and duration, increased solubility, and enhanced mildness by ethylene oxide-propylene oxide copolymers. As described in these various patents, the addition of polymers to LDLDs can aid performance in many important attributes of the product. 

Surfactants containing phosphonic acid head groups have also been used to prepare surface-imprinted polymers for organic molecules. Yoshida et al. [22,23] synthesized polymers with imprinted surfaces capable of distinguishing amino acid enantiomers. The monophosphonic acid w-DDP (Fig. 4) was used as the host molecule in water in oil emulsion polymers imprinted with the methyl ester of tryptophan. 

Palmitoyl hydroxypropyltrimonium amylopectin/glycerin crosspolymer Definition Palmitic acid ester of a polymer of the hydroxypropyltrimonium deriv. of amylopectin crosslinked with glycerin Uses Skin conditioner in cosmetics Palmitoyl keratin amino acids Definition Condensation prod, of palmitic acid chloride and keratin amino acids Uses Antistat, surfactant, foaming agent, wetting agent for cosmetics, hair care, skin care... 

Proteins are themselves surface-active compounds with an amphiphilic nature. The interfacial behavior of proteins is different from that of low-molecular-weight amphiphiles with a simple structure, namely, detergents, because proteins are highly complex polymers made up of a combination of 20 different amino acids (this point is described in detail in Chapter 3 of this book). Normally, proteins take on the folded compact structure, in which nonpolar amino acid residues are located in the interior and hydrophilic residues are exposed to molecular surfaces. Since hydrophobic interactions play dominant roles in the adsorption of surfactants to the air-water and oil-water interfaces, such a native structure of proteins should be modified to make fiiU use of the surface activity of proteins [1]. 

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