Subject micellar parameters

Correlations of micellar electrophoretic retention parameters with standard measures of lipophilicity, mostly logP, have been the subject of numerous publications (138-141]. QSRR studies of the molecular mechanism of MEEKC in terms of LSER-based structural descriptors of analytes were reported by Abraham et al. (142]. 

The fractional binding of counterions to ionic micelles is commonly denoted by the parameter /S. It follows that the corresponding micellar charge is l-fi [176]. Work on classic micellar systems such as dodecyl sulfate and octanoate show that this subject is highly complicated and as yet not fully understood [176-179]. In the presence of different counterions (such as the alkali ions Li", Na, K, Rb and Cs ), micellar size and shape, CMC values and CMT values of dodecyl sulfate are altered and do not follow the order of atomic number of the alkali ions in the periodic table nor their hydrated radius (P.J. Missel, G.B. Benedek and M.C. Carey, unpublished observations). Hydrated radius bears an inverse relationship to atomic radius, viz. (in A) Li (2.35), Na (1.85), (1.32), Cs+ (1.27) and Rb" (1.26). A... 

Micelles of low molecular weight surfactants are known to be very dynamic structures, although the various fragments of the molecules within a micelle are subject to some restrictions of mobility in comparison to molecular solution [23, 379-381]. As the hydrophilic head groups are anchored at the micellar surface , NMR-studies show that the mobility and the order parameter decreases along the alkyl tail from its end towards the head group [379-385]. 

Surfactant molecules commonly self-assemble in water (or in oil). Even single-surfactant systems can display a quite remarkably rich variety of structures when parameters such as water content or temperature are varied. In dilute solution they form an isotropic solution phase consisting of micellar aggregates. At more concentrated surfactant-solvent systems, several isotropic and anisotropic liquid crystalline phases will be formed [2]. The phase behavior becomes even more intricate if an oil (such as an alkane or fluorinated hydrocarbon) is added to a water-surfactant binary system and the more so if other components (such as another surfactant or an alcohol) are also included [3], In such systems, emulsions, microemulsions, and lyotropic mesophases with different geometries may be formed. Indeed, the ability to form such association colloids is the feature that singles out surfactants within the broader group of amphiphiles [4]. No wonder surfactants phase behavior and microstructures have been the subject of intense and profound investigation over the course of recent decades. 

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