Growth micellar

A. Bernheim-Groswasser, E. Wachtel, and Y. Talmon. Micellar growth, network formation, and criticality in aqueous solutions of the nonionic surfactant C12E5. Langmuir, 16(9)4131 1140, 2000. 

O. Glatter, G. Fritz, H. Lindner, J. Brunner-Popela, R. Mittelbach, R. Strey, and S. U. Egelhaaf. Nonionic micelles near the critical point Micellar growth and attractive interaction. Langmuir, 16(23) 8692-8701, 2000. 

Because of the above-mentioned multimodal detection capability of the CONTIN computer program, photon correlation spectroscopy has been used effectively by Flamberg and Pecora (ref. 466) to detect translational and rotational motions of micelles in solution. The results obtained can best be explained by a micellar growth model. 

In polymerizations where desorption is very high, all micelles grow simultaneously. This is because radical absorption is followed almost iimiediately by desorption with only a brief micellar growth period. As a result, all micelles experience an equal but intermittant growth. The number of latex particles is determined solely by the number of micelles initially present. The number of micelles, m, is given by the expression... 

A similar interpretation of phase diagrams has been recently proposed by Safran and Turkevich (18). These authors have considered the effects of interaction and curvature on the stability of microemulsions. They suggest that unstabilities of spherical microemulsion droplets lead the system to separate with water in order to prevent micellar growth above a limit radius R. Taking into account interactions with a phenomenologic treatment, they show that phase separation due to interaction is also possible and they found a critical radius Rc. If Rc is greater than R a water phase is formed and if Rc is lower than R phase separation gives rise to two micellar phases with a critical point. This theoretical treatment reflects very well the behavior we observe but it is not in full accordance with our experimental results. The main difference is that when interactions are not preponderant the phase separation does not occur with a water phase but with a lamellar phase. 

We would like to point out that this micellar growth is probably not the type of transition from spherical to cylindrical micelles as usually observed in a concentrated surfactant solution (31,32). 

Menge, U., Lang, P. and Findenegg, G.H. (2000) Influence oftemperature and oil-to-surfactant ratio on micellar growth in aqueous solutions ofC12E5 with decane. Colloids Surf. A, 163, 81-90. 

The average size of bile salt micelles and the distribution of micellar sizes around the mean value are important physical-chemical characteristics of a bile salt solution [5,6]. Because bile salt micellar growth is sensitive to total detergent concentration within the micellar phase, with temperature and ionic strength, the physical-chemical conditions must be rigorously controlled and specified [5,6]. Further, most... 

Although this model is consistent with many properties of micelles it has major shortcomings. For example, many workers have argued that geometrical constraints favor a spheroidal rather than a strictly spherical micelle, and extensive micellar growth is inconsistent with a spherical geometry [34]. 

Although it is reasonable to believe that micelles in water are close to spherical at low surfactant concentrations, e.g., within an order of magnitude of the critical micelle concentration, there is evidence for micellar growth with increasing surfactant or electrolyte concentration. Such growth cannot easily be accommodated to a strictly spherical structure for the micelle, but requires it to become spheroidal. Solutions of some surfactants become very viscous on addition of salts. For example, addition of iodide, arenesulfonate or aromatic carboxylate ion to cationic surfactants sharply increases solution viscosity, suggesting that long, rod-like micelles are formed. 

A number of workers are now taking these interactions into account in their treatments [46-48], and it appears that micellar growth is less than had originally been supposed [45], and the evidence of quasi-elastic light scattering leads to estimates of micellar size consistent with those from other methods [46-48]. 

The reactions involved in the preparation of synthetic zeolites of the type described above are relatively complex. The silicate and the aluminum salts form their respective hydroxides at rates dependii on pH and concentration. There is no reason to assume a coprecipitation in the sense of an intermolecular mixing of the components. A more tenable concept is that-of micellar growth and intermicellar linkages which lead to gel formation, as proposed by Flank (28). Evidently, the alumina micelles or particles are sufficiently influenced by the surrounding silica So that they behave as an acid and thus combine with the positive ions present, in this case sodium ion, to give a ratio of one sodium ion to one aluminum ion as long as the amounts of alumina do not exceed 30 per cent by weight of the silica-alumina. 

Bijma, K., Rank, E., and Engberts, J. B. F. N., Effect of counterion structure on micellar growth of alkylp5n idinium surfactants in aqueous solution, J. Colloid Interface Sci., 205, 245—256 (1998). 

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