Surfactant association structure

The role of various surfactant association structures such as micelles and lyotropic liquid crystals (372), adsorption-desorption kinetics at liquid-gas interfaces (373) and interfacial rheology (373) and capillary pressure (374) on foam lamellae stability has been studied. Microvisual studies in model porous media indicate... 

T1he importance of association structures of amphiphilic molecules for interfacial phenomena has been realized in the last ten years with the rapid progress of knowledge concerning the structure of biomembranes and the discovery of the pronounced influence of surfactant association structures on the properties of disperse systems. 

The surfactant association structures have a long history of research ranging from the McBaln introduction of the aqueous micellar concept(1.) over the interpretation of mlcelllzatlon as a critical phenomenon — — to the analysis of the structure of lyotropic liquid crystals(A) and the comprehensive picture of the phase relations in water/surfactant/amphlphile systems.These studies have emphasized the relation between the association structures in isotropic liquid solutions and the liquid crystalline phases. Parallel extensive investigations in crystalline/ liquid crystalline lipid structureshave provided important insight in the mechanisms of the associations. 

The main concern of the investigations discussed so far was the self-association of the hydrotrope molecules. Although such a subject constitutes an interesting area of research, it must be kept in mind that the hydrotrope molecule functions as a modifier of surfactant association structures in the majority of its applications. It is, hence, of interest to review available material on the alteration of surfactant association structures by addition of a hydrotrope. 

One of the major steps to enhancing the understanding of surfactant association structures is to investigate the phase equilibria of water-oil-surfactant mixtures. Since the pioneering contributions of P. Ekwall in Scandinavia and K. Shinoda in Japan, who analyzed ternary systems containing ionic and nonionic surfactants, respectively, extensive experimental work has been devoted to different kinds of microemulsion systems [7-20]. During recent decades, detailed descriptions of the phase behavior of many ternary (water-oil-surfactant), quaternary (water-oil-surfactant-alcohol), and even quinary (water-oil-surfactant-alcohol-salt) systems have been presented (for example, see Refs. 21-36). These studies have provided evidence for several new phases where the surfactant creates surfaces. Thus, in addition to bicontinuous microemulsions, one finds dilute lamellar phases (L ) [37-43] and liquid isotropic phases of randomly connected bilayers called... 

S. Fnberg and P. O. Jansson. Surfactant association. structure and emulsion stability. J. Colloid interj. ScL 55 614-62.3. 1976. 

Figure 3. A Schematic Illustration of Surfactant Association Structures.

Surfactant Association Structures, Microemulsions and Emulsions in Food... 

These systems are widely used in many food products. A section will be devoted to the interfedal phenomena in food colloids, in particular their dynamic properties and the competitive adsorption of the various components at the interlace. The interaction between proteins eind polysaccharides in food colloids will be briefly described. This is followed by a section on the interaction between polysaccharides and surfactants. A short review will be given on surfactant association structures, microemulsions and emulsions in food [3]. Finally, the effect of food surfactants on the interfacial and bulk rheology of food emulsions will be briefly described. The formation of aggregation networks and the application of fractal concepts is then considered. This is followed by a section on applications of rheology in studying food texture and mouth feel. 

Surfactant association structures, microemulsions and emulsions in food... 

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