Mixed surfactant systems

Fig. IV 23. Penetration of cholesterol monolayers by CTAB (hexadecyl-trimethylam-monium bromide. [From D. M. Alexander, G. T. Barnes, M. A. McGregor, and K. Walker, Phenomena in Mixed Surfactant Systems, in J. F. Scamehom, ed., ACS Symposium Series 311, p. 133, 1986 (Ref. 269). Copyright 1986, American Chemical Society.]...

Mixed Surfactant Systems, edited by Keizo Ogino and Masahiko Abe... 

The net result is that detergency performance for mixed active formulations is not so drastically reduced by high water hardness conditions. The improvement in detergency by mixed surfactant systems can be seen not only in under-... 

FIG. 2 CMC of linear alkylbenzenesulfonate-a-olefmsulfonate (LABS-AOS) mixed surfactant system. (From Ref. 3.)... 

Defoaming Theory and Industrial Applications, edited by P. R. Garrett Mixed Surfactant Systems, edited by Keizo Ogino and Masahiko Abe Coagulation and Flocculation Theory and Applications, edited by Bohusiav DobiaD Biosurfactants Production Properties Applications, edited by Naim Kosaric Wettability, edited by John C. Berg... 

Xia J. et alii, "Effects of Different Distributions of Lyophobic Chain Length on the Interfacial Properties of Nonaethoxylated Fatty Alcohol" in "Phenomena in Mixed Surfactant Systems", J.F. Scamehom, Ed. 1986, ACS Stmposium Series 311, Wash. 

Scamehom, J.F. Phenomena in Mixed Surfactant Systems American Chemical Society, Symposium Series Washington, DC 1986. 

Minssieux L., "Method for Adsorption Reduction of Mixed Surfactant Systems", Proc. 4th. Eur. EOR Symp., 1987, p. 293. 

Among the purposes of this paper is to report the results of calorimetric measurements of the heats of micellar mixing in some nonideal surfactant systems. Here, attention is focused on interactions of alkyl ethoxylate nonionics with alkyl sulfate and alkyl ethoxylate sulfate surfactants. The use of calorimetry as an alternative technique for the determination of the cmc s of mixed surfactant systems is also demonstrated. Besides providing a direct measurement of the effect of the surfactant structure on the heats of micellar mixing, calorimetric results can also be compared with nonideal mixing theory. This allows the appropriateness of the regular solution approximation used in models of mixed micellization to be assessed. 

Calorimetric measurements can be used to obtain heats of mixing between different surfactant components in nonideal mixed micelles and assess the effects of surfactant structure on the thermodynamics of mixed micellization. Calorimetry can also be successfully applied in measuring the erne s of nonideal mixed surfactant systems. The results of such measurements show that alkyl ethoxylate sulfate surfactants exhibit smaller deviations from ideality and interact significantly less strongly with alkyl ethoxylate nonionics than alkyl sulfates. 

The mixed cmc behavior of these (and many other) mixed surfactant systems can be adequately described by a nonideal mixed micelle model based on the psuedo-phase separation approach and a regular solution approximation with a single net interaction parameter B. However, the heats of micellar mixing measured by calorimetry show that the assumptions of the regular solution approximation do not hold for the systems investigated in this paper. This suggests that in these cases the net interaction parameter in the nonideal mixed micelle model should be interpreted as an excess free energy parameter. 

Fig.1 Formation of reverse micelles in a self-assembled mixed surfactant system. The addition of water tends to link these droplets to form a highly viscous bi-continuous microemulsion with aqueous and isooctane nanochannels separated by the surfactants...

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