Micellar aggregation numbers values

Explain why the data on micellar aggregation numbers in Table 3-1 for ionic surfactants often include the surfactant concentration at which the value was determined (the value in parentheses in the table), while the data for nonionics and zwitterionics do not include the concentration. 

Whereas micellar aggregation numbers are now routinely determined, we know much less about the water and ion content of the micelles. Estimates of the water content of C3Ms range up to 92 %, similar to values obtained for macroscopic coacervates [19, 53-55]. Several groups have used fluorescent probes, such as auramine O, pyrene and l,3-di-(l-pyrenyl)-propane (P3P), to assay the polarity and microviscosity of the micellar core and C3V membrane [47, 56,57]. Estimates of the micro-ion content of microscopic coacervates are lacking. Experimental and theoretical studies on the salt concentration of macroscopic coacervates report at most small differences in ionic strength inside and outside the coacervate phase [7, 8, 58]. Exceptionally, for example, in coacervates of poorly water-soluble polyelectrolytes, there may be larger differences in salt content [7,8]. 

Some CMC values and aggregation numbers found for one of the most extensively studied ionic surfactants in non-aqueous medium, sodium bis(2-ethylhexyl) sul-fosuccinate (AOT), are listed in Table 13.2. It is clear that the CMC values, as well as the micellar aggregation numbers, are very small when compared to aqueous systems. 

Pyrene shown a number of photophysical features that made it an attractive fluorophore to probe the microenvironment in micellar aggregates [19]. For the peaks of pyrene PL, two important peaks at about 373 nm and 390 nm among the five dominant peaks of pyrene fluorescence were numbered as 1 and III, respectively [20]. It has been known that intensity ratio of peak 111 to I (III/I) increased as the polarity at the solubilization site of pyrene decreases. Figure 6 shows fluorescence spectra (A.ex = 310 nm) of pyrene in precursor gel containing TPA and I-IV samples denoted as (a), (b), (c), (d) and (e), respectively. The value of 111/1 of pyrene does not change under silicalite-1 gel due to no formation of micelle. However, in the Fig. 6d (sample II), III/I ratio is rapidly increased, while sample III and IV are decreased slightly again. Previously, Park et al. have reported that 111/1 ratio of pyrene for... 

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