Colloidal systems hydration number

Micellar dispersions, which contain micelles along with individual surfactant molecules, are the typical examples of lyophilic colloidal systems. Micelles are the associates of surfactant molecules with the degree of association, represented by aggregation number, i.e. the number of molecules in associate, of 20 to 100 and even more [1,13,14]. When such micelles are formed in a polar solvent (e.g. water), the hydrocarbon chains of surfactant molecules combine into a compact hydrocarbon core, while the hydrated polar groups facing aqueous phase make the hydrophilic shell. Due to the hydrophilic nature of the outer shell that screens hydrocarbon core from contact with water, the surface tension at the micelle - dispersion medium interface is lowered to the values othermodynamic stability of micellar systems with respect to macroscopic surfactant phases. 

Lyotropic numbers N o, Table 5.1, were assigned to ions in the 30s of the last century by Buchner and Voet (Buchner et al. 1932 Voet 1937a, 1937b) according to their effects on colloidal systems. The lyotropic series has nowadays been to some extent superseded by the Hofmeister series, with which it is taken to be practically synonymous, but it is not so exactly. For the alkali metal cations and the halide anions the lyotropic numbers obtained from colloidal phenomena are linearly related to their enthalpies of hydration. Voet (1937a) concluded that the lyotropic series are simply related to the electric field strengths of the ions. Note that the Myo values for the alkali metal cations are not commensurate with those of the alkaline earth cations and with those of the anions. 

In the past 4-5 years, quite a number of relevant review articles and books have appeared. These included general reviews on NMR of polymers (1 10), reviews on solid state NMR (11-15), solid state multidimensional techniques (16-19), spatially resolved techniques (20), solid state NMR studies of polymer dynamics and structure (21), hydrated polymers (22), vulcanized elastomers (23), crosslinked polymers (24), and polymer networks (25), Reviews have also been written on polymer gels (26-28), polymer colloids (29), polymer-surfactant systems (30), and polymers on surfaces (31). 

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