Surfactants synergism

The synergism of surfactant-polymer complex formation has been studied by gel permeation chromatography [114],... 

Arnaud, N., and Georges, J. (2003) Comprehensive study of the luminescent properties and lifetimes of Eu(3 + ) and Tb(3 + ) chelated with various ligands in aqueous solutions Influence of the synergic agent, the surfactant and the energy level of the ligand triplet. Spectrochim. Acta A Mol. Biomol. Spectrosc. 59(8), 1829-1840. 

Cocamidopropyl betaine (Table 1.4) is the most prominent representative of the class of amphoteric surfactants. Due to the synergism with other surfactants and its gentleness to the skin and mucous membranes, cocamidopropyl betaine performs well in shampoo and cosmetics where its dosage lies in the order of 1-5% [27]. 

The use of zwitterionic surfactants commercially has increased dramatically in recent years (U because of their unique properties, such as compatibility and synergism when used in conjunction with most other types of surfactants. This type of surfactant is used in textile processing aids, cosmetic products, cleaning agents, and as antistatic agents. The sulfobetaines have been found to be very good lime soap disperants ( ). 

Only case (2) can provide a comparison between conventional and micellar extraction. The few comparisons reported in the literature on the metal extraction performance of microemulsions containing an extractant with that of the extractant on its own are, at first sight, contradictory. In some cases microemulsions produce both synergism and extraction rate enhancement with respect to the single surfactant, whereas in others they... 

We may consider precipitation in these systems in the context of competitive aggregate formation between micelles and precipitate. Even systems forming ideal mixed micelles can exhibit synergisms in salinity/hardness tolerance in such systems, the more components present, the higher the tolerance. This is the reason that mixtures of isomeric surfactants generally have Krafft temperatures considerably lower than those of the individual compounds (90). 

In mixed surfactant systems, physical properties such as the critical micelle concentration (cmc) and interfacial tensions are often substantially lower than would be expected based on the properties of the pure components. Such nonideal behavior is of both theoretical interest and industrial importance. For example, mixtures of different classes of surfactants often exhibit synergism (1-3) and this behavior can be utilized in practical applications ( ).In addition, commercial surfactant preparations usually contain mixtures of various species (e.g. different isomers and chain lengths) and often include surface active impurities which affect the critical micelle concentration and other properties. 

Molecular Interaction and Synergism in Binary Mixtures of Surfactants... 

Non-ideal solution theory is used to calculate the value of a parameter, S, that measures the interaction between two surfactants in mixed monolayer or mixed micelle formation. The value of this parameter, together with the values of relevant properties of the individual, pure surfactants, determines whether synergism will exist in a mixture of two surfactants in aqueous solution. 

The conditions for synergism in surface tension reduction efficiency, mixed micelle formation, and Surface tension reduction effectiveness in aqueous solution have been derived mathematically together with the properties of the surfactant mixture at the point of maximum synergism. This treatment has been extended to liquid-liquid (aqueous solution/hydrocarbon) systems at low surfactant concentrations.) The effect of chemical structure and molecular environment on the value of B is demonstrated and discussed. 

During the past few years, the determination of the interfacial properties of binary mixtures of surfactants has been an area in which there has been considerable activity on the part of a number of investigators, both in industry and in academia. The Interest in this area stems from the fact that mixtures of two different types of surfactants often have interfacial properties that are better than those of the individual surfactants by themselves. For example, mixtures of two different surface-active components sometimes reduce the interfacial tension at the hydrocarbon/water interface to values far lower than that obtained with the individual surfactants, and certain mixtures of surfactants are better foaming agents than the individual components. For the purpose of this discussion we define synergism as existing in a system when a given property of the mixture can reach a more desirable value than that attainable by either surface-active component of the mixture by itself. 

Synergism in surface tension reduction efficiency. The efficiency of surface tension reduction by a surfactant is defined (9) as the solution phase concentration required to produce a given surface tension (reduction). Synergism in this respect is present in a binary mixture of surfactants when a given surface tension (reduction) can be attained at a total mixed surfactant concentration lower than that required of either surfactant by itself. This is illustrated in Figure 2. 

Figure 3. Synergism in surface tension reduction efficiency for some binary surfactant mixtures.

Synergism in mixed micelle formation. Synergism in this respect is present when the critical micelle concentration of any mixture is lower than that of either pure surfactant. This is illustrated in Figure 2. 

The cmc at the point of maximum synergism, i.e., the minimum total mixed surfactant concentration in the solution phase required for mixed micelle formation, C 2 nin given by the relationship ... 

Synergism in surface tension reduction effectiveness. This exists when the mixture of surfactants of its cmc reaches a lower surface tension than that obtained at the cmc of either component of the mixture by Itself. This is illustrated in Figure 5. 

Figure 5. Synergism in surface tension reduction effectiveness. (Ycmc 2 Y°cmc or Y°cmC2). (l) Pure surfactant 1 ...

Data on systems showing synergism in this respect indicate that for surfactants containing a single hydrophilic and a single hydrophic group, the point of maximum synergism is reached when... 

Our data, to date, show that molecular interaction between two surfactants, both in mixed monolayers at the aqueous solution/air interface and in mixed micelles in aqueous solution, increases in the order POE nonionic-POE-nonionic < POE nonionic-betaine < betaine-cationic < POE nonionic-ionic (cationic, anionic) betaine-anionic cationic-anionic. The greatest probability of synergism exists, therefore, in cationic-anionic mixtures, followed by betaine-anionic mixtures. Synergism can exist in POE nonionic-ionic mixtures only if the surfactants involved have the proper structures. 

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