Interactions fatty acids, sulfonates

Figure 7 Mesoporous silica grafting for catalysis enhanced activity towards glycerol esterification is obtained when a hydrophobic methyl chain is cografted with the sulfonate function, providing favorable interactions with fatty acid reagents...

On the other hand, despite the information about long chain sulfates, sulfonates, phosphates, and carboxylates that indicates stronger interaction with Ca2+ than with Mg2+ (i.e., in apparent harmony with the sequence of the Hofmeister (44) series), several difficulties remain. For example, while Miyamoto s data for DS (10) indicate the interaction sequence Mg < Ca < Sr < Ba from solubility measurements (as well as from temperature/CMC measurements if one accepts the Mg—Ca sequence of the present paper), this sequence, with the exception of the position of Mg and Ca, is the opposite of that found by Deamer et al. (33) from condensation effects on the force/area curves of ionized fatty acids. At the same time, the ion sequence obtained by these authors from phase transition temperatures of spread fatty acids (33) differs from that deduced from the above-mentioned condensation effects, and the latter depended strongly on pH. Lastly, definite differences in ion sequence effects exist for the alkaline earth metals in their interaction with long... 

Chemical interactions The chemical contribution may result from interactions such as covalent or complex bond formation between the surfactants and the surface sites. Surfactants such as fatty acids, alkyl sulfates, alkyl sulfonates, amines and alkylhydroxa-mates have been proposed to adsorb by means of chemical interactions on a variety of particles. In addition, surfactants containing hydroxyl, phenolic, carboxylic and amine groups can hydrogen-bond with the surface sites. Infrared spectroscopy has been used to understand the chemisorption of surfactants at the surface, by examining the shift in the characteristic peaks of the surfactants upon adsorption. 

The ability of exogenous proteins to reduce the skin and eye irritation potential of detergents was highlighted many decades ago in the cosmetic chemistry community. First extensive insights were probably those of Meinecke (4), who reported that addition of a protein hydrolysate or a protein-fatty acid condensate to a solution of a highly irritant surfactant (sodium alkylbenzene sulfonate) caused a remarkable increase in the skin tolerability of the product and postulated a protective effect based on the formation of a protein colloidal layer on the skin, which could prevent or minimize the direct interaction of tenside molecules with skin keratin. The same interpretation has been advanced more recently by other authors (116-118). 

Shape memory elastomers were prepared from mixtures of a sulfonated EPDM ionomer and fatty acid salts, FAS, (ZnOleate),. Physical crosslinks in the ionomer that arise from inter-chain ionic interactions provide a permanent shape, while the crystalline low molecular weight FAS provides the means for a temporary shape. The material can be deformed above the melting point (T ) of the FAS and the new shape can be fixed by cooling the material under stress to below Tm of the FAS. Polar interactions between the ionomer and the FAS stabilize the dispersion of the FAS in the polymer and provide the continuity between the phases that allows the crystals of the FAS to provide a second network of physical crosslinks. 

Water that is bound to the surfactant aggregates plays a role in interactions with the polar groups. It was shown that micelles can bind considerably more water than is accounted for by hydration of the alkali metal ions. This was taken as evidence that the carboxylate or sulfonate groups bind water through ion-dipole interaction and/or hydrogen bonds. Fatty carboxylic acid and carboxylate groups are linked by hydrogen bonds (AHA, A(HA)2 ), A(HA)n ). These effects have been demonstrated in many other surfactant systems (Ekwall, 1969 Ekwall and Mandell, 1967 Ekwall and Solyom, 1967 Ekwall et al., 1972). 

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